ADVANTAGES OF CRITICAL PATH METHOD (CPM)

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ADVANTAGES OF CRITICAL PATH METHOD(CPM)

The critical path methods (CPM) have been used for

planning and scheduling in construction projects. The

use of CPM varies from user to user, with some

contractors feeling that CPM is a waste of time and

money. With the time, the use of project

management technique have improved with

experience. Most likely, the unsuccessful applications

of CPM resulted from trying to use a level of detail far

too complicated for practical use, or the schedule was

developed by an outside firm with no real input by

the user, or the CPM diagram was not reviewed and

updated during the project.

Critical Path Method

Experience with the application of CPM on several projects has revealed the following

advantages of Critical Path Method:

1. CPM encourages a logical discipline in the planning, scheduling, and control of projects.

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ADVANTAGES OF CRITICAL PATH METHOD (CPM)

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2. CPM encourages more long-range and detailed planning of projects.

3. All project personnel get a complete overview of the total project.

4. CPM provides a standard method of documenting and communicating project plans, schedules,

and time and cost performances.

5. CPM identifies the most critical elements in the plan, focusing management’s attention to the 10

to 20% of the project that is most constraining on the scheduling.

6. CPM provides an easy method for evaluating the effects of technical and procedural changes that

occur on the overall project schedule.

7. CPM enables the most economical planning of all operations to meet desirable project completion

dates.

An important point to remember is that CPM is an open-ended process that permits different degrees

of involvement by management to suit their various needs and objectives. In other words, you can

use CPM at whatever level of detail you feel is necessary. However, one must always remember that

you only get out of it what you put into it. It will be the responsibility of the user to choose the best

technique. They are all good, and they can all be used effectively in the management of construction

projects; just pick the one best liked and use it.

ANALYSIS OF RATES FOR BUILDING WORKS

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ANALYSIS OF RATES FOR BUILDING WORKS

Analysis of rates for building works is the process of

separation of works into components/elements (Viz.

Labour, materials, machinery,transport, overheads

and profit) of work and pricing them.

Analysis of rates is required for:

Insertion in a tender (i.e.) as a lump sum, item

rates

To check reasonability of rates inserted by

tenderers

To assess various quantities of labour, materials,

machinery, money and to effect economy by using

alternatives and to optimize the resources

To assess the rates payable for deviations, extra items of work to the builder

To compare the costs with sanctioned amount and to take action for regularization of excess/ less

cost

To workout the budget and cash flows at various stages of the work and arranging interim/ final

payments

To detect irrational rates quoted by tenderers

To serve as basic data in case of disputes that may arise at a later stage

Analysis of rates for building works

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ANALYSIS OF RATES FOR BUILDING WORKS

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Analysis of rates consists of rates of following elements:

a) Material cost inclusive of wastage

b) Labour cost

c) Plant & machinery owning and operating charges

d) Water charges

e) Taxes

f) Insurance/ risk coverage charges

g) Contractor’s overheads and profit

Following points are considered while preparing analysis of rates:

1. Percentage profits & overhead charges:

Element of profit normally varies from 5 to 10%. Overheads vary from 3 to 7 ½%. The total element

of overheads and profit shall not normally exceed 17 ½% on estimated rates. This should be

restricted to 10% if paid bills/ days work is considered.

2. Cement constants:

The cement constants for various items of work including wastage of 2 ½%. These constants are

based on observations made by CBRI Roorkie, concrete association of India, CPWD, MES and other

construction organizations. The constants are shown in Appendix ‘A’.

3. Material constants:

Cost of materials includes the supplier’s price, transportation, loading/ unloading, haulage to site,

handling for incorporation into the work, wastages/breakage/pilferage, storage charges,

ANALYSIS OF RATES FOR BUILDING WORKS

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deterioration on storage, returning of empty bags/ cases and taxes and other incidentals. The

constants in use in various departments and organizations is as per Appendix ‘B’.

4. Labour output constants:

Some of the labour output constants are covered in IS – 7272. The constants given by NBO, CPWD,

MES, State governments are also considered and given in Appendix ‘C’.

5. Specification of various building materials:

Generally the building materials shall conform to the relevant Indian standards. Where no such

standards exist the relevant British/ American standards in so far as they are applicable could be

followed. The materials of local origin (Within 40 km or distance as specified) shall be best available

and approved by competent authority.

6. Basic costs: Cost of materials, labour, machinery, tools & plant (depreciated cost), and direct

overheads connected to the particular project.

7. Indirect costs: Not directly related to the project but otherwise involved. The corporate office

expenses, consultant charges, outsourced costs etc.

8. Daily wages: Wages which the builder is bound to pay to labour which will not be less than

statutory wages.

9. All in rates: Wages + proportionate element of terminal benefits such as bonus, gratuity.

10. Standing charges: Includes element of depreciation, interest whereas running charges include

cost of operation of plant, POL, operator & supporting staff.

11. Fixed/ variable overheads: fixed overheads are those incurred only once like construction of

site office, where as variable overheads are salaries paid and other expenses as per employment of

labour hours every month.

12. Standard schedule of rates: Many organizations/ departments shall have schedule of rates of

materials/ items of works. These schedules contain specifications for materials & methods giving

references to relevant Indian standards. The schedules are revised at periodic intervals of 3 to 5

years or yearly. In certain cases certain percentage addition/ deduction is specified to bring them in

ANALYSIS OF RATES FOR BUILDING WORKS

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line with market rates.

13. Derived rates: The rates derived by interpolation/ extrapolation of rates inserted in the

contract. For e.g. – The rate for PCC 1:3:6 can be derived from quoted rate for PCC 1:4:8. The rate

for M-20 can be derived from quoted rate for M- 25 concrete.

14. Star rates/ Market rates: The rates worked out based on market enquiry/ quotations and

applying the percentage above/ below for similar quoted trade items plus overheads and profit.

Alternately rates worked out for material/ labour based on paid bills/ vouchers produced by

contractor plus profit.

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BUILDING CRACKS- CAUSES & REMEDIES

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BUILDING CRACKS- CAUSES & REMEDIES

Causes of Cracks in concrete structures:

The principal causes of occurrence of cracks in a

building are as follows:

1. Permeability of concrete.

As deterioration process in concrete begins with

penetration of various aggressive agents, low

permeability is the key to its durability. Concrete

permeability is controlled by factors like water-

cement ratio, degree of hydration/curing, air voids

due to deficient compaction, micro-cracks due to

loading and cyclic exposure to thermal variations. The first three are allied to the concrete strength

as well. The permeability of cement paste is a function of water-cement ratio given good quality

materials, satisfactory proportioning and good construction practice; the permeability of the concrete

is a direct function of the porosity and interconnection of pores of the cement paste.

2. Thermal movement:

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BUILDING CRACKS- CAUSES & REMEDIES

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Thermal movement is one of the most potent causes of cracking in buildings. All materials more or

less expand on heating and contract on cooling. The thermal movement in a component depends on

a number of factors such as temperature variations, dimensions, coefficient of thermal expansion

and some other physical properties of materials. The coefficient of thermal expansion of brickwork in

the vertical direction is fifty percent greater than that in the horizontal direction, because there is no

restraint to movement in the vertical direction.

Thermal variations in the internal walls and intermediate floors are not much and thus do not cause

cracking. It is mainly the external walls especially thin walls exposed to direct solar radiation and the

roof which are subject to substantial thermal variation that are liable to cracking.

Remedial Measures:

Thermal joints can be avoided by introducing expansion joints, control joints and slip joints. In

structures having rigid frames or shell roofs where provision of movement joints is not structurally

feasible, thermal stresses have to be taken into account in the structural design itself to enable the

structure to withstand thermal stresses without developing any undesirable cracks.

3. Creep

Concrete when subjected to sustained loading exhibits a gradual and slow time dependant

deformation known as creep. Creep increases with increase in water and cement content, water

cement ratio and temperature. It decreases with increase in humidity of surrounding atmosphere

and age of material at the time of loading. Use of admixtures and pozzolonas in concrete increases

creep. Amount of creep in steel increases with rise in temperature.

BUILDING CRACKS- CAUSES & REMEDIES

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4. Corrosion of Reinforcement

A properly designed and constructed concrete is initially water-tight and the reinforcement steel

within it is well protected by a physical barrier of concrete cover which has low permeability and high

density. Concrete also gives steel within it a chemical protection. Steel will not corrode as long as

concrete around it is impervious and does not allow moisture or chlorides to penetrate within the

cover area. Steel corrosion will also not occur as long as concrete surrounding it is alkaline in nature

having a high pH value.

Concrete normally provides excellent protection to reinforcing steel. Notwithstanding this, there are

large number of cases in which corrosion of reinforcement has caused damage to concrete structures

within a few years from the time of construction. One of the most difficult problems in repairing a

reinforced concrete element is to handle corrosion damage. Reinforcement corrosion caused by

carbonation is arrested to a great extent through repairs executed in a sound manner. However, the

treatment of chloride-induced corrosion is more difficult and more often the problem continues even

after extensive repairs have been carried out. It invariably re-occurs in a short period of time.

Repairing reinforcement corrosion involves a number of steps, namely, removal of carbonated

concrete, cleaning of reinforcement application of protection coat, making good the reduced steel

area, applying bond coat and cover replacement. Each step has to be executed with utmost care.

When chlorides are present in concrete, it is extremely difficult to protect reinforcing steel from

chloride attack particularly in cases where chlorides have entered through materials used in

construction and residing in the hardened concrete.

This increase in volume causes high radial bursting stresses around reinforcing bars and result in

local radial cracks. These splitting cracks results in the formation of longitudinal cracks parallel to the

bar. Corrosion causes loss of mass, stiffness and bond and therefore concrete repair becomes

inevitable as considerable loss of strength takes place

Corrosion of steel in a canopy

Corrosion of steel in a canopy

Remedial Measures:

Reinforcement steel in concrete structures plays a very important role as concrete alone is not

capable of resisting tensile forces to which it is often subjected. It is therefore important that a good

physical and chemical bond must exist between reinforcement steel and concrete surrounding it. Due

to inadequacy of structural design and /or construction, moisture and chemicals like chlorides

BUILDING CRACKS- CAUSES & REMEDIES

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penetrate concrete and attack steel. Steel oxidizes and rust is formed. This results in loss of bond

between steel and concrete which ultimately weakens the structure.

The best control measure against corrosion is the use of concrete with low permeability. Increased

concrete cover over the reinforcing bar is effective in delaying the corrosion process and also in

resisting the splitting.

5. Moisture Movement:

Most of the building materials with pores in their structure in the form of intermolecular space

expand on absorbing moisture and shrink on drying. These movements are cyclic in nature and are

caused by increase or decrease in inter pore pressure with moisture changes.

Initial shrinkage occurs in all building materials that are cement/lime based such as concrete,

mortar, masonry and plasters. Generally heavy aggregate concrete shows less shrinkage than light

weight aggregate concrete.

Controlling shrinkage cracks.

Shrinkage cracks in masonry could be minimized by avoiding use of rich cement mortar in masonry

and by delaying plaster work till masonry has dried after proper curing and undergone most of its

initial shrinkage. In case of structural concrete shrinkage cracks are controlled by using temperature

reinforcement. Plaster with coarse well graded sand or stone chip will suffer less from shrinkage

cracks and is preferred for plastering for external face of walls.

Considering the building as a whole, an effective method of controlling shrinkage cracks is the

provision of movement joints. The work done in cold weather will be less liable to shrinkage cracks

than that in hot weather since movement due to thermal expansion of materials will be opposite to

that of drying shrinkage.

6. Poor Construction practices.

The construction industry has in general fallen prey to non-technical persons most of whom have

little or no knowledge of correct construction practices. There is a general lack of good construction

practices either due to ignorance, carelessness, greed or negligence. Or worse still, a combination of

all of these.

BUILDING CRACKS- CAUSES & REMEDIES

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The building or structure during construction is in its formative period like a child in mother’s womb.

It is very important that the child’s mother is well nourished and maintains good health during the

pregnancy, so that her child is healthily formed. Similarly for a healthy building it is absolutely

necessary for the construction agency and the owner to ensure good quality materials selection and

good construction practices. All the way to building completion every step must be properly

supervised and controlled without cutting corners.

Some of the main causes for poor construction practices and inadequate quality of buildings are

given below:

Improper selection of materials.

Selection of poor quality cheap materials.

Inadequate and improper proportioning of mix constituents of concrete, mortar etc.

Inadequate control on various steps of concrete production such as batching, mixing, transporting,

placing, finishing and curing

Inadequate quality control and supervision causing large voids (honey combs) and cracks

resulting in leakages and ultimately causing faster deterioration of concrete.

Improper construction joints between subsequent concrete pours or between concrete framework

and masonry.

Addition of excess water in concrete and mortar mixes.

Poor quality of plumbing and sanitation materials and practices.

7. Poor structural design and specifications

Very often, the building loses its durability on the blue print itself or at the time of preparation of

specifications for concrete materials, concrete and various other related parameters.

It is of crucial that the designer and specifier must first consider the environmental conditions

existing around the building site. It is also equally important to do geotechnical (soil) investigations

to determine the type of foundations, the type of concrete materials to be used in concrete and the

grade of concrete depending on chemicals present in ground water and subsoil.

It is critical for the structural designer and architect to know whether the agency proposed to carry

out the construction has the requisite skills and experience to execute their designs. Often

complicated designs with dense reinforcement steel in slender sections result in poor quality

construction. In addition, inadequate skills and poor experience of the contractor, ultimately causes

deterioration of the building.

BUILDING CRACKS- CAUSES & REMEDIES

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Closely spaced of reinforcement steel bars due to inadequate detailing and slender concrete shapes

causes segregation. If concrete is placed carelessly into the formwork mould, concrete hits the

reinforcement steel and segregates causing fine materials to stick to the steel, obstructing its

placement and is lost from the concrete mix while the coarse material falls below causing large

porosity (honeycombs).

Slender structural members like canopies (chajjas), fins and parapets often become the first target

of aggressive environment because of dense reinforcement, poor detailing, less cover of concrete to

the reinforcement steel. Added to all this, low grade of concrete and poor construction practices can

make the things worse. It is necessary for the structural consultant to provide adequate

reinforcement steel to prevent structural members from developing large cracks when loaded.

To sum up, the following precautions are required to be taken by the Architects, Structural

Consultants and Specifiers:

Proper specification for concrete materials and concrete.

Proper specifications to take care of environmental as well as sub – soil conditions.

Constructable and adequate structural design.

Proper quality and thickness of concrete cover around the reinforcement steel.

Planning proper reinforcement layout and detailing the same in slender structures to facilitate

proper placing of concrete without segregation.

Selection of proper agency to construct their designs.

Architects and Engineers are parents of the buildings they plan and design and therefore their

contribution to the health and life of the building is quite significant. Once the plans are drawn the

structural designs and specifications are prepared, it is then the turn of the agency to construct the

building and bring the blue print to reality. Special care must be taken in the design and detailing of

structures and the structure should be inspected continuously during all phases of construction to

supplement the careful design and detailing.

8. Poor Maintenance

A structure needs to be maintained after a lapse of certain period from its construction completion.

Some structures may need a very early look into their deterioration problems, while others can

sustain themselves very well for many years depending on the quality of design and construction.

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BUILDING CRACKS- CAUSES & REMEDIES

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Leakage from roof slab

Spalled concrete due to corrosion of steel

Regular external painting of the building to some extent helps in protecting the building against

moisture and other chemical attacks. Water-proofing and protective coating on reinforcement steel

or concrete are all second line of defence and the success of their protection will greatly depend on

the quality of concrete.

Leakages should be attended to at the earliest possible before corrosion of steel inside concrete

starts and spalling of concrete takes place. Spalled concrete will lose its strength and stiffness,

besides; it will increase the rate of corrosion as rusted steel bars are now fully exposed to aggressive

environment. It is not only essential to repair the deteriorated concrete but it is equally important to

prevent the moisture and aggressive chemicals to enter concrete and prevent further deterioration.

9. Movement due to Chemical reactions.

The concrete may crack as a result of expansive reactions between aggregate containing active silica

and alkalines derived from cement hydrations. The alkali silica reaction results in the formation of

swelling gel, which tends to draw water form other portions of concrete. This causes local expansion

results in cracks in the structure.

To control Cracks due to alkali-silica reactions, low alkali cement, pozzolona and proper aggregates

should be used.

10. Indiscriminate addition and alterations.

There have been some building collapses in our country due to indiscriminate additions and

alterations done by interior decorators at the instance of their clients.

Generally, the first target of modifications is the balcony. Due to the requirement to occupy more

floor area, balconies are generally enclosed and modified for different usages.

BUILDING CRACKS- CAUSES & REMEDIES

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EFFECT OF WATER TABLE ON SAFE BEARINGCAPACITY OF SOIL

Balconies and canopies are generally cantilever RCC slabs. Due to additional loading they deflect and

develop cracks. As the steel reinforcement in these slabs have less concrete cover and the balcony

and canopy slab is exposed to more aggressive external environment, corrosion of steel

reinforcement takes place and repairs become necessary.

The loft tanks are generally installed in toilets or kitchens, which are humid areas of the buildings.

The structure in addition to being overloaded is also more prone to corrosion of reinforcement steel

in these areas and therefore deteriorates and if not repaired, part of the building can even collapse.

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COARSE AGGREGATES IN HIGH STRENGTH CONCRETE

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COARSE AGGREGATES IN HIGH STRENGTHCONCRETE

COARSE AGGREGATES IN HIGH STRENGTH

CONCRETE

Given the critical role that the interfacial transition

plays in high-strength concrete, the mechanical

properties of coarse aggregate will have a more

pronounced effect than they would in conventional-

strength concrete. Important parameters of

coarse aggregate are shape, texture, grading,

cleanliness and nominal maximum size. In

conventional-strength structural concretes, it is

common for the aggregates to be stronger and stiffer

than the paste, aggregate strength is usually not

considered a critical factor; however, aggregate strength becomes increasingly important as

target strength increases, particularly in the case of high strength lightweight aggregate

concrete. Aggregate properties such as surface texture and mineralogy significantly affect the

interfacial paste-aggregate bond and the level of stress at which interfacial cracking commence.

Durability properties notwithstanding, important coarse aggregate properties to consider

includes strength, stiffness, bonding potential, and absorption. Caution should be exercised

when using extremely stiff coarse aggregates, such as diabase or granite. Depending on the desired

concrete properties, stiff aggregates can be either beneficial or detrimental. Several studies have

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COARSE AGGREGATES IN HIGH STRENGTH CONCRETE

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found that using coarse aggregates with greater stiffness can increase the elastic modulus

while at the same time decrease the strength capacity. Designing high strength concrete to act

more like a homogeneous material could enhance ultimate strength potential. This can be achieved

by increasing the similarity between the elastic modulii or coarse aggregate and paste.

As the target strength increases, the properties of aggregates as they relate to water-

demand becomes less relevant and the properties that relate to interfacial bond become

more important. Even though the water demand of smaller size coarse aggregates is higher,

having greater surface area (and correspondingly greater interfacial bonding potential), smaller

aggregates become more desirable as the target strength increases.

Rough textured and angular coarse aggregate provide greater mechanical bond and are

generally more suitable for use in high strength concrete than smooth textured aggregates.

With respect to mechanical properties, even though crushed aggregates usually outperform smooth

textured aggregates, smooth textured aggregates should be summarily dismissed from consideration

or restricted based on this characteristic alone. Depending on the required strength and other

necessary properties, clean, well shaped locally available rounded aggregates might perform

satisfactorily.

The crushing process eliminates potential zones of weakness within the parent rock, thereby making

smaller sizes more likely to be stronger than larger ones. Smaller aggregate sizes are also

considered to produce higher concrete strengths because of less sever concentrations of stress

around the particles, which are caused by differences between the elastic module of the paste and

the aggregate.

For high-strength concrete, aggregate particles should be generally cubical in shape and

should not contain excessive amounts of flat and elongated pieces. Note that the flatness and

the elongation are relative terms, and that the definitions vary by location. Coarse aggregates

containing more than approximately 20% of the particles having ratios of length to circumscribed

thickness greater than three to one, as determined by ASTM D 4791, should be avoided when

making high-strength concrete. Aggregate particles should be clean and free of any materials

that would degrade, such as organic matter, clay lumps and soft particles, or adhere to

surface during mixing and impede interfacial transition zone bond. When finally divided materials

COARSE AGGREGATES IN HIGH STRENGTH CONCRETE

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(i.e. smaller than 75micron) such as clay, shale or excessive dust of fracture remain on the surface

of aggregates after undergoing batching, mechanical bond at the interfacial transition zone

decreases.

In the case of high-strength concrete, the effect of a weakened paste to aggregate bond can be

extremely detrimental to strength. For this reason, use of clean, washed aggregate in the

production of high-strength concrete is highly suggested. Coatings that impair paste-

aggregate bond can be identified through petrographic examination of the suspect aggregate and

frequently through petrographic examination of concrete produced with the suspect aggregate.

Aggregate binding is the process of intermixing two or more aggregates to produce an aggregate

with different set of properties. It is not common industry practice to blend crushed and coarse

aggregates, however, blending crushed cubically shaped and smooth naturally rounded coarse

aggregates can be advantageous for optimizing the properties of high-strength concrete.

COARSE AGGREGATES IN HIGH STRENGTH CONCRETE

Fig: Effect of aggregate type and blend on mean 28 days compressive strength

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COMMON WALLS MATERIALS : PROPERTIES AND APPLICATIONS

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COMMON WALLS MATERIALS : PROPERTIES ANDAPPLICATIONS

Following table shows the properties components,

properties and applications of common wall materials

such as various types of bricks, partition boards etc.

Wall Building Materials

Wall Materials

Composition

Properties Applications

Fired CommonBricks (includingclay bricks,-flyash bricks, shalebricks, and coalgangue bricks )

Made by sintering the claymaterials

Compressive strength:10-30MPa;apparent density:1500-1800kg/m ;thermal conductivity:0.78W/(m*K); andfrost resistance: 15times

Walls, bases,columns, brickarches, etc..

Fired PorousBricks

Compressive strength:7.5-30MPa;apparent density:1100-1300kg/m3; andfrost resistance: 15

Insulating load-bearing walls

3

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COMMON WALLS MATERIALS : PROPERTIES AND APPLICATIONS

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times

Fired HollowBricks andBlocks

Compressive strength:2.0-5.0 MPa;apparent density:800-1100kg/m ; andfrost resistance: 15times

Non-load bearingwalls, and insulatingwalls

Lime-sand BricksMade by autoclaving groundfine silicate sand, lime andwater

Compressive strength:10-25MPa;apparent density:1800-1900kg/m3;thermal conductivity:0.6W/(m-K);the appearance isstructured and whitegrey; they also can bemade into colourfulbricks; the brickscannot resist flowingwater for a long timeand also acid corrosion

The application isalmost the samewith fired commonbricks, but theycannot be used inthe partsexperiencing flowingwater and heatabove 200 C for alongtime

Autoclaved FlyAsh Bricks

Fly ash. lime, aggregates(slag, and mineral slag) andgypsum

Compressive strength:7.5-20MPa;apparent density:1500kg/m ; the dryshrinkage of qualifiedproducts:</=0.85mm/m

The same with lime-sand bricks

Aerated ConcreteBlocks

The porous concrete made bygas-forming and autoclavingground silicate materials.lime, aluminum powder andwater

The compressivestrength of500(kg/m )grade: 2.2-3.0MPa;thermal conductivity:0.1 0-0.16W/(m.K);frost resistance: 15times;the compressivestrength of 700grade: 4.2-5.0MPa

Walls of buildingsandInsulation

Aerated ConcreteBoards (exteriorwallboards, orpartitions)

Ditto, and with steel bars Outer walls andpartition walls

Foam ConcreteBlocks

The porous concrete made bygas-forming and autoclavingcement, foam agent andwater

The common ones are400 grade and 500grade; thecompressive strengthof 500 grade is 2-3.0MPa; and the thermalconductivity is 0.12W/(m*K)

The same withaerated concrete

Common smallsized concretehollow blocks

Made by stirring and formingcement, sand, stone andwater;There are single-row pores,double row pores and triple-row pores

Compressive strength:3.5 to 15 MPa;Hole-rate: 35% –50%;Apparent density:1300 – 1700 kg/m ;Thermal conductivity:0.26 W/(m*K)

The inner walls andload-bearing wallsof low-rise andmiddle-rise buildings

3

0

3

3

3

COMMON WALLS MATERIALS : PROPERTIES AND APPLICATIONS

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Small-sizedlightweightaggregateconcrete hollowblocks

Made by stirring and formingcement, sand (light-weightsand or common sand)lightweight aggregates andwater; there are single-rowpores and multi-row pores.

Compressive strength:2.5 – 10 MPa;Apparent density: 500– 1400 kg/m

The insulating walls(<3/5 MPa) or non-load-bearing walls;load-bearing walls(>= 3.5 MPa)

Lightweightconcretewallboards

Cement, sand, lightweight,water and steel bars

Apparent density:1000 – 1500 kg/m ;Compressive strength:10-20 MPa; thermalconductivity: 0.35 –0.5 W/(m*K)

The wallboards withstrength less than15 MPa can be usedin non-load-bearingwalls; and thosewith strength morethan 15 MPa can beused in load bearingwalls

Lightweightsandwich boards

The polystyrene boards withsteel mesh plastered bycement mortar on two sides,or composite colourful thinsteel plates, aluminium alloyboards and colourfulgalvanised steel boards

Weight: 10 – 110kg/m ;Heat resistance: 0.6 –1.1 (m *K)/WSoundproof index: 40dB

Self-supportingouter walls,partitions, insulatingwalls (such asceilings, and roofboards).

Concretesandwich boards

Composed by reinforcedconcrete of 20-30 thick as thesurface layers, rock wool felt,glass fiber felt, foam concreteand other insulating materialsas the middle layer.

Load bearing board:500 – 542 kg/m ;Thermal conductivity:1.01 W/(m *K)(thickness of 250mm);Non-load-bearing: 260kg/m ;Thermal conductivity:0.593 W/(m *K)(thickness of 180mm)

Load bearing outerwalls or non-loadbearing outer walls

Paper Gypsumboards, fibregypsum boards,hollow gypsumboards anddecorativeboards

Building gypsum, paperboards, glass fibre and water

Apparent density: 600-1000 kg/m ; bendingload:400-850N;Thermal conductivity:0.2-0.25 W/(m*K);Soundproof index: 30– 50 dB;Lightweight, insulating,soundproof, easy to beprocessed and used,and poor waterresistance

Inner partitionwalls, or the boardsinside compositewalls, the relativehumidity of theenvironment > 75%and thetemperature > 60 C

Glass fibrereinforcedcement boards(GRC Boards)

Low-alkali cement, anti-alkaliglass fibre, lightweightaggregate and water

Apparent density:1880 kg/m ;Bending strength: >25kJ/m ;Thermal conductivity:<=0.2 W/(m*K);Soundproof indexes: >30 – 45 dB;Fireproof limit: 1.3 –3h; easy to be used

Inner partitionwalls, the protectiveboards on theexterior walls orcombined with othercore materials

3

3

3

2

3

2

3

2

3

0

3

2

CONCRETE FORMWORK CHECKLIST AT SITE

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Home Building Technology

CONCRETE FORMWORK CHECKLIST AT SITE

Concrete formwork is a temporary supporting

structure for concrete when it is placed at the

construction site to keep the concrete in position and

shape till it gets hardened. Checks for formwork

should be carried out before concreting, during

concreting and after removal of formwork. Concrete

formwork possesses both quality and safety threats.

If the formwork is not right for the concrete and work

is being done at height, it may cause safety issue.

Quality of concrete is affected when the formwork is

not properly aligned, not leak proof etc. Proper

storage of concrete formworks is also required to for

cost economy of the project.

CONCRETE FORMWORK CHECKLIST AT SITE:

FORMWORK CHECKLIST FOR WALLS:

Concrete Formwork Checklist for Walls

1. Ensure lateral bracings provided firmly supports the forms at all points of support.

2. Block out (stop end) braced to resist vertical and lateral loads.

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3. Form panels are adequately braced and tied with each other.

4. Formwork corners shall be adequately tied to prevent leakage or bulging and spreading of

concrete.

5. Ensure sufficient length is provided for wall ties and has sufficient strength and spacing as

required.

6. Check wales for proper proper spacing and joints between should be staggered from one tier to

the next.

7. In double member wales, one member left continuous across the location of form ties.

8. Wall ties and bolts tightened properly.

9. In case double member wales is used, both wales should have identical depths.

10. Check for adequate lap between forms and previously cast concrete.

11. Ensure that grout leakage does not occur at joints between panels and joints between old

concrete and panels above them.

12. Check the provision of resistance against uplift in case of sloping faces of concrete formwork.

13. Ensure experienced supervisor is available at site while installing the wall forms and while placing

concrete.

FORMWORK CHECKLIST DURING CONCRETING:

CONCRETE FORMWORK CHECKLIST AT SITE

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1. Before concreting commences ensure proper access for workers involved in placing, compacting

and finishing concrete.

2. Presence of experienced supervisor keeping a continuous watch for any dangerous situation.

3. Adequate supply of spare props, clamps, bolts, wedges and skilled workers at site.

4. Alignment, camber, level and plumb (verticality) maintained while concreting is in progress.

5. Effective depth between top and bottom reinforcement not disturbed.

6. Cover of concrete around reinforcement steel maintained as specified.

7. Grout loss due to movement at joints and corrective action taken against it.

8. Loosening of wedges and fixings due to vibrations transmitted to the formwork and corrective

action against it.

9. Spilt concrete and/or grout cleaned immediately.

10. All wooden spreaders, to hold vertical form faces apart, removed after placing concrete.

11. Wooden members for creating pockets eased before concrete sets fully.

12. Concrete pouring sequence as per that shown on formwork drawing (avoid eccentric loading).

13. Prevention of heaping of concrete and high impact drops from concrete buckets.

14. Rate of concreting within allowable limits as shown on working drawing or as assumed while

designing the formwork against lateral pressures.

15. Proper bond between layers of concrete, in case concrete is placed in layers, by ensuring that

needle vibrator while vibrating the top layer also penetrates the lower layer.

CONCRETE FORMWORK CHECKLIST AT SITE

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CHECKLIST DURING FORMWORK STRIKING (STRIPPING OR REMOVAL):

1. Formwork design and layout such that smooth striking of formwork in sequential manner is

possible.

2. Strength of concrete capable of taking self weight and construction load on it.

3. Removal time to be ascertained depending on size, shape and span of the member, grade of

concrete mix and its rate of gain of strength, type of cement, ambient temperature and weather

conditions and extent of curing executed.

4. At the time of removal of side form, corners and edges not damaged.

5. Ties, clamps and wedges loosened and removed gradually.

6. Removal time in line with those specified in code of practice (IS 456- 2000).

7. Props in case of beams and slabs removed in stages from mid-span working outwards.

8. Bolts, nuts, clamps, wedges collected in a box and not dropped carelessly.

9. Use of crowbars to prise open forms avoided.

10. Formwork prised loose using wooden wedges.

11. Formwork carefully lowered and not dropped and damaged.

12. Panel faces should be carefully removed and lowered without them hitting the scaffold

projections.

13. Panels placed on leveled surface after removal.

14. Nail projections hammered down.

15. Cordoning off the area below the location where formwork removal is proposed.

16. Presence of competent crane operator and foreman.

CONCRETE FORMWORK CHECKLIST AT SITE

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CHEKLIST FOR CLEANING AND STORAGE OF FORMWORK:

1. Formwork as soon as it is removed, cleaned with a stiff brush.

2. Dust, dirt, stubborn bits of concrete or grout removed.

3. Timber surface and uncoated ply coated with release agent before storing.

4. Steel form coated lightly with oil to prevent corrosion.

5. Damaged formwork sorted out and repaired before storage.

6. Depressions, nail holes repaired with suitable materials and lightly rubbed down to give smooth

surface.

7. Panels and plywood sheets stored on a horizontally leveled floor.

8. Panels stored face to face to protect the surface.

9. Storage area protected from rain and moisture and well ventilated.

10. All formwork materials stacked off the ground.

11. Loose wailing, soldiers (struts) etc. stored with respective panels after numbering for proper

match when reused.

12. Bolts, nuts, champs, pins, wedges, keys and ties stored in separate bins or boxes.

Also Read: Types of Concrete Formworks

CONCRETE FORMWORK DESIGN CONSIDERATIONS

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Home Building Technology

CONCRETE FORMWORK DESIGNCONSIDERATIONS

Designing and building formwork effectively requires

a basic understanding of how concrete behaves as it

exerts pressure on formwork. Concrete exerts lateral

pressure on the formwork. The formwork is designed

based on these lateral forces.

Lateral concrete pressure on formwork is

affected by:

1) Height of concrete pour

2) Concrete pour rate

3) Weight of concrete

4) Temperature

5) Type of cement

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6) Vibration

7) Concrete slump (water–cement ratio)

8) Chemical additives

1) Height of concrete pour: Before concrete hardens, it acts like a liquid and pushes against the

forms the way water presses against the walls of a storage tank. The amount of pressure at any

point on the form is directly determined by the height and weight of concrete above it. Pressure is

not affected by the thickness of the wall.

Lateral concrete pressure on formwork

Fig: Lateral concrete pressure on formwork

2) Concrete pour rate: Concrete pressure at any point on the form is directly proportional to the

height of liquid concrete above it. If concrete begins to harden before the pour is complete, the full

liquid head will not develop and the pressure against the forms will be less than if the pour were

completed before any of concrete hardened.

Once concrete hardens it cannot exert more pressure on the forms even though liquid concrete

continues to be placed above it. The following diagrams illustrates how form pressure varies when

the pour rate is increased from one level to another level. For ease of explanation, it is assumed that

concrete hardens in one hour (typically) at 21°C.

Fig: Concrete pressure on formwork during hardening

When the pour rate is increased the pressure also increases as shown below:

Fig: Concrete pressure on formwork due to higher pour rate

CONCRETE FORMWORK DESIGN CONSIDERATIONS

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3) Weight of Concrete: Pressure exerted against the forms is directly proportional to the unit

weight of concrete. Light weight concrete will exert less pressure than normal weight concrete as

shown below:

Fig: Pressure on formwork due to normal and lightweight concretes

4) Temperature: The time it takes concrete to harden is influenced greatly by its temperature. The

higher the temperature of the concrete, the quicker it will harden. Most formwork designs are based

on an assumed average air and concrete temperature of 21°C. At low air temperatures, the

hardening of concrete is delayed and you need to decrease your pour rate or heat your concrete to

keep the pressure against the formwork from increasing. Ideally, concrete should be poured at

temperatures between 16°C and 38°C. Outside this temperature range there is often insufficient

moisture available for curing. If adequate water for curing is not available or freezes, the strength of

the concrete will suffer.

5) Type of Cement: The cement type will influence the rate at which concrete hardens. A high early

strength concrete will harden faster than normal concrete and will allow a faster pour rate. When

using a cement which alters the normal set and hardening time, be sure to adjust the pour rate

accordingly.

6) Vibration: Internal vibration consolidates concrete and causes it to behave like the pure liquid. If

concrete is not vibrated, it will exert less pressure on the forms. ACI recommended formulas for form

pressures may be reduced 10% if the concrete is spaded rather than internally vibrated. Re-vibration

and external vibration result in higher form loads than internal vibration. These types of vibration

require specially designed forms.

7) Concrete Slump: When concrete has very low slump, it acts less like a liquid and will transmit

less pressure. When using concrete with a slump greater than 100 mm, the formwork should be

designed to resist full liquid head.

8) Chemical additives: When using chemical additives – i.e. retarders, plasticizers, etc. – make

sure to refer to the vendor’s application data.

CONSTRUCTION EQUIPMENTS FOR DIFFERENT PURPOSES

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Home Construction Construction Equipments

CONSTRUCTION EQUIPMENTS FOR DIFFERENTPURPOSES

Construction Equipments

The selection of the appropriate type and size of

construction equipments often affects the required

amount of time and effort and thus the job-site

productivity of a project. It is therefore important for

site managers and construction planners to be

familiar with the characteristics of the major types of

equipment most commonly used in construction.

Excavation and Loading

One family of construction machines used for

excavation is broadly classified as a crane-shovel as indicated by the variety of machines in Figure 1.

The crane-shovel consists of three major components:

A carrier or mounting which provides mobility and stability for the machine.

A revolving deck or turntable which contains the power and control units.

A front end attachment which serves the special functions in an operation.

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The type of mounting for all machines in Figure 1 is referred to as crawler mounting , which is

particularly suitable for crawling over relatively rugged surfaces at a job site. Other types of

mounting include truck mounting and wheel mounting which provide greater mobility between job

sites, but require better surfaces for their operation. The revolving deck includes a cab to house the

person operating the mounting and/or the revolving deck. The types of front end attachments in

Figure 2 might include a crane with hook, claim shell, dragline, backhoe, shovel and piledriver.

construction equipment

Figure 1 Typical Machines in the Crane-Shovel Family

A tractor consists of a crawler mounting and a non-revolving cab. When an earth moving blade is

attached to the front end of a tractor, the assembly is called a bulldozer. When a bucket is attached

to its front end, the assembly is known as a loader or bucket loader. There are different types of

loaders designed to handle most efficiently materials of different weights and moisture contents.

Scrapers are multiple-units of tractor-truck and blade-bucket assemblies with various combinations

to facilitate the loading and hauling of earthwork. Major types of scrapers include single engine two-

axle or three axle scrapers, twin-engine all-wheel-drive scrapers, elevating scrapers, and push-pull

scrapers. Each type has different characteristics of rolling resistance, maneuverability stability, and

speed in operation.

Compaction and Grading

The function of compaction equipment is to produce higher density in soil mechanically. The basic

forces used in compaction are static weight, kneading, impact and vibration. The degree of

compaction that may be achieved depends on the properties of soil, its moisture content, the

thickness of the soil layer for compaction and the method of compaction. Some major types of

compaction equipment are shown in Figure 2, which includes rollers with different operating

characteristics.

The function of grading equipment is to bring the earthwork to the desired shape and elevation.

Major types of grading equipment include motor graders and grade trimmers. The former is an all-

purpose machine for grading and surface finishing, while the latter is used for heavy construction

because of its higher operating speed.

CONSTRUCTION EQUIPMENTS FOR DIFFERENT PURPOSES

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Figure 2: Some Major Types of Compaction Equipment

Drilling and Blasting

Rock excavation is an audacious task requiring special equipment and methods. The degree of

difficulty depends on physical characteristics of the rock type to be excavated, such as grain size,

planes of weakness, weathering, brittleness and hardness. The task of rock excavation includes

loosening, loading, hauling and compacting. The loosening operation is specialized for rock

excavation and is performed by drilling, blasting or ripping.

Major types of drilling equipment are percussion drills, rotary drills, and rotary-percussion drills. A

percussion drill penetrates and cuts rock by impact while it rotates without cutting on the upstroke.

Common types of percussion drills include a jackhammer which is hand-held and others which are

mounted on a fixed frame or on a wagon or crawl for mobility. A rotary drill cuts by turning a bit

against the rock surface. A rotary-percussion drill combines the two cutting movements to provide a

faster penetration in rock.

Blasting requires the use of explosives, the most common of which is dynamite. Generally, electric

blasting caps are connected in a circuit with insulated wires. Power sources may be power lines or

blasting machines designed for firing electric cap circuits. Also available are non-electrical blasting

systems which combine the precise timing and flexibility of electric blasting and the safety of non-

electrical detonation.

Tractor-mounted rippers are capable of penetrating and prying loose most rock types. The blade or

ripper is connected to an adjustable shank which controls the angle at the tip of the blade as it is

raised or lowered. Automated ripper control may be installed to control ripping depth and tip angle.

In rock tunneling, special tunnel machines equipped with multiple cutter heads and capable of

excavating full diameter of the tunnel are now available. Their use has increasingly replaced the

traditional methods of drilling and blasting.

Lifting and Erecting

CONSTRUCTION EQUIPMENTS FOR DIFFERENT PURPOSES

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Derricks are commonly used to lift equipment of materials in industrial or building construction. A

derrick consists of a vertical mast and an inclined boom sprouting from the foot of the mast. The

mast is held in position by guys or stifflegs connected to a base while a topping lift links the top of

the mast and the top of the inclined boom. A hook in the road line hanging from the top of the

inclined boom is used to lift loads. Guy derricks may easily be moved from one floor to the next in a

building under construction while stiffleg derricks may be mounted on tracks for movement within a

work area.

Tower cranes are used to lift loads to great heights and to facilitate the erection of steel building

frames. Horizon boom type tower cranes are most common in highrise building construction. Inclined

boom type tower cranes are also used for erecting steel structures.

Mixing and Paving

Basic types of equipment for paving include machines for dispensing concrete and bituminous

materials for pavement surfaces. Concrete mixers may also be used to mix Portland cement, sand,

gravel and water in batches for other types of construction other than paving.

A truck mixer refers to a concrete mixer mounted on a truck which is capable of transporting ready

mixed concrete from a central batch plant to construction sites. A paving mixer is a self propelled

concrete mixer equipped with a boom and a bucket to place concrete at any desired point within a

roadway. It can be used as a stationary mixer or used to supply slipform pavers that are capable of

spreading, consolidating and finishing a concrete slab without the use of forms.

A bituminous distributor is a truck-mounted plant for generating liquid bituminous materials and

applying them to road surfaces through a spray bar connected to the end of the truck. Bituminous

materials include both asphalt and tar which have similar properties except that tar is not soluble in

petroleum products. While asphalt is most frequently used for road surfacing, tar is used when the

pavement is likely to be heavily exposed to petroleum spills.

Construction Tools and Other Equipment

Air compressors and pumps are widely used as the power sources for construction tools and

equipment. Common pneumatic construction tools include drills, hammers, grinders, saws,

wrenches, staple guns, sandblasting guns, and concrete vibrators. Pumps are used to supply water

or to dewater at construction sites and to provide water jets for some types of construction.

CONSTRUCTION EQUIPMENTS FOR DIFFERENT PURPOSES

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Automation of Equipment

The introduction of new mechanized equipment in construction has had a profound effect on the cost

and productivity of construction as well as the methods used for construction itself. An exciting

example of innovation in this regard is the introduction of computer microprocessors on tools and

equipment. As a result, the performance and activity of equipment can be continually monitored and

adjusted for improvement. In many cases, automation of at least part of the construction process is

possible and desirable. For example, wrenches that automatically monitor the elongation of bolts and

the applied torque can be programmed to achieve the best bolt tightness. On grading projects, laser

controlled scrapers can produce desired cuts faster and more precisely than wholly manual methods.

In the mid-1980’s, some Japanese firms were successful in obtaining construction contracts for

tunneling in the United States by using new equipment and methods. For example, the Japanese

firm of Ohbayashi won the sewer contract in San Francisco because of its advanced tunneling

technology. When a tunnel is dug through soft earth, as in San Francisco, it must be maintained at a

few atmospheres of pressure to keep it from caving in. Workers must spend several hours in a

pressure chamber before entering the tunnel and several more in decompression afterwards. They

can stay inside for only three or four hours, always at considerable risk from cave-ins and

asphyxiation. Ohbayashi used the new Japanese “earth-pressure-balance” method, which eliminates

these problems. Whirling blades advance slowly, cutting the tunnel. The loose earth temporarily

remains behind to balance the pressure of the compact earth on all sides. Meanwhile, prefabricated

concrete segments are inserted and joined with waterproof seals to line the tunnel. Then the loose

earth is conveyed away. This new tunneling method enabled Ohbayashi to bid $5 million below the

engineer’s estimate for a San Francisco sewer. The firm completed the tunnel three months ahead of

schedule. In effect, an innovation involving new technology and method led to considerable cost and

time savings.

CONSTRUCTION OF CONCRETE FOUNDATION

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CONSTRUCTION OF CONCRETE FOUNDATION

Construction of concrete foundation is divided into

number of work activities with specific objectives and

completion time for each activity is defined. Each

activity for construction of concrete foundations has

to be planned, as it requires specific equipments at

every stage. Activities for construction of concrete

foundations can be divided into following:

1. Marking of foundation layout at site.

2. Earth excavation upto the required depth by

means of machine.

3. Earth excavation and levelling of soil by means of hand operated tools.

4. Placing of PCC.

5. Placement of reinforcement steel

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6. Erection of concrete formworks for footings.

6. Placement of concrete and vibrating and levelling of concrete surface.

7. Removal of formwork after the concrete has set.

8. Curing of concrete for the required number of days.

9. Applying finishing coats on concrete surface.

10. Site cleanup.

11. Backfilling of excavation upto the required depth in the number of layers.

Each activity for the construction of foundation requires different skill sets of workmen and different

equipments. For a construction large construction projects, there can be many number of

foundations to be casted on a single day. Therefore it is required to plan each and every activity of

this construction. The project planner for foundation construction should determine the quantity of

works involved in each activity and estimate the quantity of materials to be required. The number of

tools and equipments, workforce and other resources to be utilised for this construction should be

well planned in advance. For example the placement of concrete could involve the total number of

cubic meters of concrete involved in the activity. The building of forms would normally be measured

by the square meter of concrete surface area.

Construction project activties

Fig: Construction project activities

All the acitivities for a foundation construction must be properly sequenced and resources required at

different times of the activity must be estimated. From this information the possible necessary to

complete the construction and the amount of resources required can be known. At this point the

planner might not considered factors such as delays due to weather and other unforceen

circumstances. The construction plan for foundation is affected by following:

The ability of the contractor to accomplish the project.

The resulting costs of the project.

CONSTRUCTION OF CONCRETE FOUNDATION

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FOUNDATION TYPES AND USES

Next article

UNIT COST METHOD OF ESTIMATION

The rate of concreting for foundation construction should be estimated to complete the work within

the time. The concrete work should not be stopped for more than 30 minutes unless all the

concretng has been completed.

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CONSTRUCTION PROJECT COST ESTIMATING

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Home Construction Construction Management

CONSTRUCTION PROJECT COST ESTIMATING

Estimating the cost of a proposed construction

project is a very complex process containing much

variable factors.Proper study, training and experience

are needed to become proficient in this area of

engineering. There are several categories that can

have significant impacts on project costs. The

estimator should be aware of them and properly

evaluate their effects.

Prior to finalizing the cost estimate. Here are some

important points:

1) Similar Projects: The best references are similar projects. Refer to their final cost items and

related expenses as a sound basis. Experience with similar projects is invaluable.

2) Material Costs: Obtain reliable costs for materials and supplies, plus shipping charges, prior to

commencing tabulation.

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3) Wage Rates: Determine if the project will mandate state or federal wage rates. Also, check if

local wage rates are required. It is mandatory to factor this into the estimate.

4) Site Conditions: Project site conditions that can increase construction costs are: poor soil

conditions, wetlands, contaminated materials, conflicting utilities (buried pipe, cables, overhead

lines, etc.), environmentally sensitivity area, ground water, river or stream crossings, heavy traffic,

buried storage tanks, archaeological sites, endangered species habitat and similar existing

conditions.

5) Inflation Factor: The presence of inflation is always a factor that can be extremely variable.

When utilizing previous, similar projects as a primary basis for estimating, consider the Construction

Cost Index as published in the Engineering News Record. This nationwide tabulation of the

construction industry has been continuously recorded for decades.

6) Bid Timing: The timing of the bid opening can have a significant impact on obtaining a low bid.

Seasonal variations in construction activity and conflicts with other bid openings are critical factors.

7) Project Schedule: The construction schedule can certainly affect the cost. If the project requires

too aggressive of a time frame, generally the price increases, especially if there is a significant

liquidated damages condition for failure to complete within a specified deadline. Conversely, if the

award notice is beyond a reasonable time and the notice to proceed is indefinite, the contractors fear

inflation of material costs and may have other projects that have priority. Therefore, most bidders

will inflate their bids to protect against these conditions. Any time beyond 60 days may result in

higher bids.

8) Quality of Plans & Specifications: There is no substitute for well-prepared plans and

specifications. It is extremely important that every detail and component of the design be properly

executed and fully described. Any vague wording or poorly drawn plan not only causes confusion, but

places doubt in the contractor’s mind which generally results in a higher bid.

9) Reputation of Engineer: If the project engineer or engineering firm has a good sound

professional reputation with contractors, it is reflected in reasonably priced bids. If a contractor is

comfortable working with a particular engineer, or engineering firm, the project runs smoother and

therefore is more cost-effective.

10) Granting Agency: If a granting agency is involved in funding a portion of the project,

contractors will take this into consideration when preparing their bids. Some granting agencies have

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considerable additional paperwork that is not normally required in a non-funded project. Sometimes

this expected extra paperwork elevates the bid.

11) Regulatory Requirements: Sometimes there are conditions in regulatory agency approvals

that will be costly to perform. Therefore, to be completely aboveboard with potential bidders, it is

strongly recommended that copies of all regulatory approvals be contained in all bidding documents.

12) Insurance Requirements: General insurance requirements, such as performance bond,

payment bond and contractors general liability are normal costs of doing business. However, there

are special projects that require additional coverage. Railroad crossings are a prime example.

Insurance premiums for these supplemental policies add to the project cost and must be considered

up front.

13) Size of Project: The size and complexity of a project determines if local contractors have the

capacity to execute the work. The larger and more intricate the proposed project is, the more it will

potentially attract the attention of a broader number of prospective bidders. This is good for

competition, but may increase mobilization costs.

14) Locale of Work Site: The locale of the proposed work can be a significant component in

developing a realistic cost estimate. A rural setting usually has a limited labor force skilled in the

construction trades. Therefore, the contractor must import tradesmen and generally pay per diem

expenses; i.e., out-of-town lodging and related costs. Additionally, remote settings increase the

charges for material shipment.

15) Value Engineering: Some agencies mandate that multi-million dollar projects perform a value

engineering review, prior to finalizing the design or commencing the bidding process. Therefore, the

estimator should be aware of this factor early in the process.

16) Contingency: The rule-of-thumb has historically added a 10% contingency on the construction

total to cover those unforeseen costs that crop up as a project evolves. During times of high inflation

or the limited amount of key construction materials and supplies, it is wise to increase the

contingency to 15% or 20% for a more realistic estimate and provide a safety factor.

17) Supplemental Studies & Investigations: some project sites will require special studies

and/or investigations. Costs for this special work should be included in the initial cost estimate to

avoid future surprises.

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18) Judgement: In the final analysis, the best component of a good cost estimate is the art of

practicing sound technical judgement. This factor is acquired by experience and the mentoring of

senior personnel.

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CONSTRUCTION PROJECT DEVELOPMENT FROM SCRATCH

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CONSTRUCTION PROJECT DEVELOPMENTFROM SCRATCH

The development of any project follows some major

phases in project life cycle. For the success of the

project, the project team must successfully plan,

organize and control their work activities so that they

are performed in proper sequence and on time. Some

parts of the major phases of project life cycle is

performed before the construction phase starts.

Following are the steps involved in development

of a construction project from scratch:

1. Conceptual phase

2. Proposal phase

3. Project design phase

a) Engineering design

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b) Procurement of major equipment

c) Project control function

d) Construction inputs from experienced engineers

4. Procurement of other construction materials

5. On-site construction

6. Facility start-up and turnover

Construction project development from scratch

1. Conceptual Phase of Construction Project:

This phase of construction project is generally done by owner or client with the help of consultants,

project managers and other experienced engineers. The major activities in this phase can be:

Product development

Process development

Marketing surveys

Setting project scope and design basis

Capital cost estimating

Project financing plans

Economic feasibility studies

Board approval of the project

When client develops a need for new facility for any reason, the need for new construction project

arises. Then client with the help of their R&D team, consultants and project managers etc., does the

above steps during the conceptual phase of the project. Market research for the product

development need, capital cost estimating of the project, project financing plans and project scope

and design basis are the important part of this phase.

2. Proposal Phase of the Construction Project:

Once the construction project gets approval from the board, then the project enters proposal phase.

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In this phase the main goal is to select a suitable contractor to carry out the construction activity as

required by the client or owner. This phase involves following activities:

Preparing a contracting plan – like terms and conditions of contract, payment terms, security

deposit, earnest money deposit etc.

Prequalifying contractor slate – prequalification needed for a contractor to carry out the

project is finalized, like size of project executed by the contract, type of project executed by the

contractor etc.

Preparing a request for proposal (RFP) or Request for Quotation (RFQ – this involves bill

of quantities of each item of work to be executed in the construction project, and quotation for

the same is requested from the contractor.

Receiving and analyzing the proposals- each quotation received by the means of tendering is

then opened and analysed as per the requirement of the client. Then client decides on selection of

the best proposal based on cost and quality in mind and contractors work experience.

Selecting the best proposal

Negotiating a contract: after the best proposal is selected by the client, the selected contractor

is called for negotiation. In this step, generally contractors are requested to review the rates

quoted by them so as to minimize the cost of the project.

3. Project Execution Phase of the construction Project:

After a suitable contractor is selected by the client or owner, the project manager is ready to execute

the project in accordance with the contracting plan. The construction project is initiated in this

phase. The following activities are generally carried out by the contractor (project manager):

Engineering design phase: it covers those activities required to generate the plans and

specifications for the procurement of the equipment and construction materials and the

construction of the facility. Process design, mechanical design, civil, architectural and structural

design, piping design, electrical design, instrumentation design, general specifications and

construction input from past experiences and other experienced engineers are the major activities

in this phase.

Equipment procurement activity: procurement of construction materials and equipment are

carried out during design stage and transported to the construction site as specified and on time

to meet the construction schedule. Interaction between construction groups and procurement

groups becomes much important during this phase of the construction.

Project control functions: to meet the project goals relating to budget, schedule, and quality

effectively, a team of control specialists performs the necessary project control functions. All the

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project commitments and expenditures are monitored by cost engineers to see that they conform

to the budget and cash flow projections. Weekly and monthly project reports are prepared to

ensure that various activities are as planned or to take any steps to keep the activities on track.

Construction field activities: each team member is presented with certain jobs on site for the

construction of the project on time and as per contracting terms. The construction manager

delegates the major areas of the construction project. The group of engineers is led by a field

superintendent who directly reports to the construction manager. This superintendent is assisted

in executing the construction work by an organization of area engineers, craft superintendents,

general foremen, and sub-contractor supervisors. All other field groups perform their duties to

support the field construction operation.

The field engineer receives and distributes the technical documents for the field organization. They

manage the design construction interface to ensure that the project is built according to the design

documents. All design clarifications, design and field changes, change orders, as built drawings,

vendor assistance contacts, and the like must pass through the field engineering office.

The engineer is also responsible for the quality control operations. This involves quality control

testing services, laboratory reports, radiography services etc. the field engineer also maintains

copies of the applicable codes and government regulations and interprets their application to the

project.

4. Facility start-up activities

This is the last activity on the project. This step establishes the order for putting the operating units

into service. The amount of construction participation in the startup must also be considered in the

scope of services along with the money and resource plans for the overall project.

CONSTRUCTION PROJECT PLANNING OBJECTIVES

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CONSTRUCTION PROJECT PLANNINGOBJECTIVES

Construction project planning is a process of

documenting action based plans for completion of

project in time. Construction project planning

includes defining the work task, sequence of work,

construction methods, roles and responsibilities and

planning of resources to complete the work as per

schedule.

The documents for construction planning includes

designs and drawings, quantity estimates,

construction methods to be adopted, contract

documents, site conditions, market survey, local

resources, project environment and the client’s

requirements.

Construction Project Planning Objectives

The objectives of a construction project planning should be:

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1. Planning of each activity:

The construction project planning should identify and include every activity of the project in a

sequential order. Every activity should be scheduled in a timeline for tracking of construction project.

2. Construction Methods:

Plans should include construction methods to be adopted for different construction activities and

tools and planning for tools and tackles for each activity so that they can be made available

whenever required.

3. Planning for Construction Equipments and Machinery:

Cost of a construction varies greatly with the use of construction equipments and heavy machinery

as their renting cost could be very high per day. So, planning and scheduling for such equipments

and machinery should be done in advance so that project activities goes on smoothly without

keeping these equipments in waiting. Project should be planned in such a way that the use of these

machinery can be made to maximum during the given period to make it cost effective.

4. Procurement of materials:

Project planning should also include procurement planning for materials. It is not advisable to keep

the material unused for site for long time. This can degrade the material as well as much of the cost

is spent on such materials. So, proper planning of material procurement also helps to complete the

project within budget.

5. Planning for employee skills:

Some of the construction activities requires availability of skilled person to execute that work. It is

not necessary to employ such person throughout the project, so proper planning of such work can

reduce the cost of operation for that activity.

6. Planning for required documents and drawings:

Construction projects are executed based on the drawings and specifications. It is necessary to track

and make available these drawings at site on time so that the construction activities are not

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Construction Project Construction Projects

Planning

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stopped. Thus construction project planning should also include the schedules of drawings,

specifications and other documents to be made available at site for review and execution without

delaying the project.

7. Financial Planning:

Financial planning of construction is the most important aspects. Different amounts are required at

different stages of construction project. Proper planning of funds for construction helps the project

proceed smoothly. There is no point in investing all the budgeted amount on the construction project

during start of the project. This can be done in phases as and when required.

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EFFECTS OF AGGREGATE PROPERTIES ON CONCRETE

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EFFECTS OF AGGREGATE PROPERTIES ONCONCRETE

Concrete is a mixture of cementitious material,

aggregate and water. Aggregate is commonly

considered inert filler, which accounts for 60 to 80%

of the volume and 70 to 85% of the weight of the

concrete. Although aggregate is considered inert

filler, it is a necessary component that defines the

concrete’s thermal and elastic properties and

dimensional stability.

concrete-aggregate

Physical and mineralogical properties of aggregate

must be known before mixing concrete to obtain a

desirable mixture. These properties include shape and texture, size gradation, moisture content,

specific gravity, reactivity, soundness, and bulk unit weight. These properties along with water

/cementitious material ratio determine the strength, workability and durability of the concrete.

The shape and texture of the aggregate affects the properties of fresh concrete more than hardened

concrete. Concrete ids more workable when smooth and rounded aggregate is used instead of rough

angular or elongated aggregate. Crushed stone produces much more angular and elongated

aggregate, which have a higher surface to volume ratio better bond characteristics but require more

cement paste to produce a workable mixture.

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TAGS Aggregates Building Materials Concrete Technology propertiesofconcrete

The surface texture of the aggregate can be either smooth or rough. A smooth surface can improve

workability yet a rougher surface generates a stronger bond between the paste and the aggregate

creating a higher strength.

The grading or size distribution of aggregate is an important characteristic because it determines the

paste requirement for workable concrete. The required amount of the concrete paste is dependent

upon the amount of void space that must be filled and the total surface area that must be covered.

When the particles are of uniform size the spacing is the greatest but when a range of sizes is used

the void spaces are filled, the less workable the concrete becomes, therefore, a compromise between

workability and economy is necessary.

The moisture content of an aggregate is an important factor when developing the proper

water/cementitious material ratio.

The density of the aggregate is required in mixture proportioning to establish weight- volume

relationships.concre

ESTIMATING LIFE OF RESIDENTIAL BUILDING

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ESTIMATING LIFE OF RESIDENTIAL BUILDING

There are different methods of estimating the life of

a building. This can be done by carrying out health

check up of the building. Depending on the degree of

sophistication and desired accuracy level vis-a-vis the

problem in hand ,there are many equipment and

methodologies available to evaluate the probable life

of a structure. Many times a thorough visual

inspection reveals the distress and the causes.

residential-building

Equipments used for HEALTH CHECK UP of the

building are:

REBOUND HAMMER: It senses the soundness of concrete up to a marginal depth.

IMPACT ECHO TESTER: Finds out defects in the interior of concrete.

ULTRASONIC TESTERS: Scans through the concrete for the full depth/thickness.

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COVER METER: Finds out the cover to the reinforcement (steel bars inside the concrete).

PROFOMETER: Establishes configuration and quantum of interior reinforcements (steel bars inside

the concrete)

REBAR PHOTOGRAPHER: Displays interior reinforcements (steel bars) skeleton.

ENDOSCOPIC DEVICE: To examine the void in the concrete.

THERMOGRAPHIC CAMERA: To locate possible defect in a new building.

CRACK MEASUREMENT DEVICE: It measures surface cracks.

PERMEABILITY TESTER: Tests for water penetration in concrete.

THICKNESS GAUGE: Measures the thickness from the surface.

LEAK SEEKER: It locates source of leakages.

COROSION ANALYZER: It measures the extent of corrosion in reinforcements. Corrosion is

regarded as equivalent of cancer in the concrete.

X-RAY: Scans inside the concrete.

Carbonation tests

Ground penetrating radar (GPR)

Vibration characteristics

EXCAVATION HAZARDS- THEIR EFFECTS AND PREVENTION

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EXCAVATION HAZARDS- THEIR EFFECTS ANDPREVENTION

Different types of hazards are associated with

excavation of soil. These hazards should be identified

and preventive measures should be taken to avoid

any accident at construction sites. The following table

highlights hazards associated with excavation of soil

during construction, their types, effects and

preventive measures.

TYPE OFEXCAVATION

TYPE OFHAZARD

EFFECT OFHAZARD

PREVENTIVE MEASURESPit excavationupto 3m

Falling into pit Personal injury Provide guard rails / barricade withwarning signalProvide atleast two entries / exitsProvide escape ladders

Earth collapse Suffocation/breathlessnessBuried

Provide suitable size of shoring andstrutting if required.Keep soil heaps away from the edgeequivalent to 1.5m or depth of pitwhichever is more.Don’t allow vehicles to operate too closeto excavated areas. Maintain atleast 2mdistance from the edge of cut.Maintain sufficient angle of repose.

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EXCAVATION HAZARDS- THEIR EFFECTS AND PREVENTION

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Provide slope not less than 1:1 andsuitable depth of excavation in all soilsexcept hard rock.Battering / benching the sides.

Contact withburied electriccableGas / OilPipelines

ElectrocutionExplosion

Obtain permission from competentauthorities prior to excavation ifrequired.Locate the position of buried utilities byreferring to plant drawings.Start digging manually to locate theexact position of buried utilities andthereafter use mechanical means.

Pit excavationbeyond 3m

Same as aboveplus floodingdue toexcessive rain/ undergroundwater

Can causedrowning situation

Prevent ingress of waterProvide ring buoysIdentify and provide suitable sizedewatering pump or well point system

Digging in thevicinity ofexistingbuilding /structure

Building /structure maycollapseLoss of health andwealth

Obtain prior approval of excavationmethod from local authorities.Use under-pinning method.Construct retaining wall side by side.

Movement ofvehicles /equipmentsclose to theedge of cut.

May cause cave-inor slides.Person may getburied.

Barricade the excavated area withproper lighting arrangements.Maintain atleast 2m distance from edgeof cut and use stop blocks to preventover-run.Strengthen shoring and strutting.

Narrow deepexcavations forpipelines etc.

Same as aboveplus frequentcave-in orslides

May cause severeinjuries or provefatal.

Battering / benching of sides.Provide escape ladders.

Flooding due tohydro-statictesting

May arisedrowning situation

Same as above.Bail out accumulated water.Maintain adequate ventilation.

Rockexcavation byblasting

Improperhandling ofexplosives

May prove fatal Ensure proper storage, handling andcarrying of explosives by trainedpersonnel.Comply with the applicable explosiveacts and rules.

Uncontrolledexplosion

May cause severeinjuries or provefatal.

Allow only authorized persons to performblasting operations.Smoking and open flames are to bestrictly prohibited.

Scattering ofstone pieces toatmosphere

Can hurt people Use PPEs like goggles, face mask,helmets etc.

Entrapping ofpersons /animals

May cause severeinjuries or provefatal

Barricade the area with red flags andblow siren before blasting.

Misfire May explodesuddenly

Do not return to site for atleast 20min orunless announced safe by designatedperson.

Piling work Failure of pile-driving

Can hurt people Inspect piling rigs and pulley blocksbefore the beginning of each shift/

EXCAVATION HAZARDS- THEIR EFFECTS AND PREVENTION

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equipmentNoise pollution Can cause

deafness andpsychologicalimbalance.

Use personal protective equipments likeear plugs, muffs etc.

Extrudingrods/casing

Can hurt people Barricade the area and install signboardsProvide first aid

Working in thevicinity of live-electricity

Can causeelectrocution /asphyxiation

Keep sufficient distance from liveelectricity as per relevant standardcodes.Shut off the supply if possible.Provide artificial / rescue breathing tothe injured.

excavation-hazard

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FACTORS AFFECTING CONSTRUCTION COST ESTIMATE

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FACTORS AFFECTING CONSTRUCTION COSTESTIMATE

Preparation of a construction cost estimate for

any project is a very complex process. Process of

construction cost estimation contains many variable

factors. Every variable has to be correctly estimated

based on proper study, past experience and research

to calculate total project cost of construction.

Construction Cost Estimate for Projects

There are many factors which affect the construction cost estimate and have significant impact on

project cost and they are as following:

1) Similar Construction Projects: For the construction estimate, the best reference will be similar

construction projects. The final cost of those similar projects can give the idea for the new

construction project cost calculation. The final cost of past project needs to be factored with current

construction cost indices.

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FACTORS AFFECTING CONSTRUCTION COST ESTIMATE

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2) Construction Material Costs: Construction material cost consists of material cost, shipping

charges and taxes applicable if any. So, it is important consider all these variations while calculating

construction material cost.

3) Labor Wage Rates: Labor wages varies place to place. So, local wage rate should be considered

in calculation. If the project has to be started after several months of estimating the project cost,

the probable variation in wage rates has to be considered in the calculation.

4) Construction Site Conditions: Project site conditions can increase construction costs. Site

conditions such as poor soil conditions, wetlands, contaminated materials, conflicting utilities (buried

pipe, cables, overhead lines, etc.), environmentally sensitivity area, ground water, river or stream

crossings, heavy traffic, buried storage tanks, archaeological sites, endangered species habitat and

similar existing conditions etc. can increase the project cost during construction phase if these

variations are not considered during estimation.

5) Inflation Factor: A construction project can continue for years before completion. During the

construction period, the cost of materials, tools, labors, equipments etc. may vary from time to time.

These variation in the prices should be considered during cost estimation process.

6) Project Schedule: Duration of construction project is affects the cost. Increase in project

duration can increase the construction project cost due to increase in indirect costs, while reduction

in construction cost also increases the project cost due to increase in direct costs. Therefore,

construction project schedules also need to be considered during project cost estimation.

7) Quality of Plans & Specifications: A good quality construction plans and specifications reduces

the construction time by proper execution at site without delay. Any vague wording or poorly drawn

plan not only causes confusion, but places doubt in the contractor’s mind which generally results in a

higher construction cost.

8) Reputation of Engineer: Smooth running of construction is vital for project to complete in time.

FACTORS AFFECTING CONSTRUCTION COST ESTIMATE

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The cost of projects will be higher with sound construction professional reputation. If a contractor is

comfortable working with a particular engineer, or engineering firm, the project runs smoother and

therefore is more cost-effective.

9) Regulatory Requirements: Approvals from regulatory agencies can sometimes be costly. These

costs also need to be considered during cost estimate.

10) Insurance Requirements: Cost estimation for construction projects should also need to

consider costs of insurance for various tools, equipments, construction workers etc. General

insurance requirements, such as performance bond, payment bond and contractors general liability

are normal costs of construction projects. In some special projects, there can be additional

requirements which may have additional costs.

11) Size and Type of Construction Project: For a large construction project, there can be high

demand for workforce. For such a requirements, local workmen may not be sufficient and workmen

from different regions need be called. These may incur extra costs such projects and also for the

type of construction project where specialized workforce is required.

12) Location of Construction: When a location of construction project is far away from available

resources, it increases the project cost. Cost of transportation for workmen, equipments, materials,

tools etc. increases with distance and adds to the project cost.

13) Engineering Review: Sometimes it is necessary to carry out technical review of construction

project to make sure the project will serve the required purpose with optimum operational and

maintenance cost. This review cost shall also be added to the project cost.

14) Contingency: It is always advisable to add at least 10% contingency towards the total project

costs for unforeseen costs and inflation.

FIELD CONDITION SURVEY OF BUILDING

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FIELD CONDITION SURVEY OF BUILDING

Field condition survey of a building is to research its

present condition and performance. The plans,

specifications and any other pertinent construction

documents describes how a building was constructed,

the strengths of materials used and the intended

purpose of individual building components. This

information combined with information on previous

repairs and additions, can assist with assessing the

in-use loading conditions for comparison to the

design intent for altered structures experiencing

distress.

Reviewing the construction drawings and/or

examining the structure will help determine the type of concrete construction. Some of the concrete

configurations encountered include plain concrete, often found in footings, dams, and residential

construction, cast-in-place reinforced concrete, prestressed-precast concrete, and post-tensioned

concrete.

field condition survey of building

During the field survey, the dimensions listed on the construction plans should be spot-checked

for consistency and verification of the plans. If the plans are not available, the existing conditions of

the building is measured, and the necessary plans, grid, elevations and sections is developed by

hand. The level of detail of the field sketches depend upon the level of details required for the

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FIELD CONDITION SURVEY OF BUILDING

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survey. On copies of drawings or field sketches, the existing are documented and categorized. The

existing conditions that should be surveyed are:

Cracks: The types and widths of the cracks are measured and recorded. If the cracks are identified

as active, a monitor is installed to record any movement.

Joints: The configurations and conditions of all joints are recorded along with any noted deficiencies.

Delamination: Areas of delamination are identified by type (partial delamination or full) and their

depth is recorded.

Spalling: Locations, depths, and conditions of spall should be recorded.

Paste Erosion: Paste erosion may be due to a chemical reaction with the paste or through erosion.

Environmental conditions that may have had an impact on the area should be noted.

Water Infiltration: Signs of water infiltration should be documented, along with whether the leaks

were active at the time of the survey. Infiltration associated with rust staining or efflorescence

should be identified accordingly.

Exposed Steel: The extent and condition of exposed steel should be documented.

Corrosion: Noted corrosion may include surface staining due to corrosion of the embedded steel

and surface-mounted components.

Structural Distress: Possible indications of structural distress include excessive deflection, shear

cracking, tension-zone cracking, radial cracking at columns, etc.

Freeze/Thaw: Areas of freeze/thaw damage should be identified and the depths of the damage

recorded.

Alkali-Silica: Areas of alkali-silica damage should be identified. Alkali-silica damage should be

sampled for confirmation of the condition through laboratory testing.

FIELD CONDITION SURVEY OF BUILDING

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TAGS Buildings Crack Repair Inspection of structure

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SPLICING OF REINFORCEMENT BARS

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REPLACEMENT CONCRETE: MATERIALS ANDAPPLICATIONS

Organics: Organic matter growing on concrete surfaces is often indicative of excess moisture. Both

the moisture and organic growth can deteriorate the concrete. Organic growth may also obscure

damage to the concrete. The area should be carefully reviewed for signs of concrete distress.

Any previous repairs should be documented, including if the repair coincides with an observed

defect. General conditions of the facility should also be documented. The locations, conditions, and

configurations of any surface treatments, equipment, fixtures, and utilities should also be

documented.

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FIELD TESTS ON CEMENT

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Home Building Technology Building Materials

FIELD TESTS ON CEMENT

Field tests on cements are carried to know the quality

of cement supplied at site. It gives some idea about

cement quality based on colour, touch and feel and

other tests.

field-tests-on-cement

The following are the field tests on cement:

(a) The colour of the cement should be uniform. It

should be grey colour with a light greenish shade.

(b) The cement should be free from any hard lumps.

Such lumps are formed by the absorption of moisture from the atmosphere. Any bag of cement

containing such lumps should be rejected.

(c) The cement should feel smooth when touched or rubbed in between fingers. If it is felt rough, it

indicates adulteration with sand.

(d) If hand is inserted in a bag of cement or heap of cement, it should feel cool and not warm.

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TAGS Cement How To Guide Material Testing Guide

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(e) If a small quantity of cement is thrown in a bucket of water, the particles should float for some

time before it sink.

(f) A thick paste of cement with water is made on a piece of glass plate and it is kept under water for

24 hours. It should set and not crack.

(g) A block of cement 25 mm ×25 mm and 200 mm long is prepared and it is immersed for 7 days in

water. It is then placed on supports 15cm apart and it is loaded with a weight of about 34 kg. The

block should not show signs of failure.

(h) The briquettes of a lean mortar (1:6) are made. The size of briquette may be about 75 mm ×25

mm ×12 mm. They are immersed in water for a period of 3 days after drying. If cement is of sound

quality such briquettes will not be broken easily.

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FIRE PROTECTION OF HIGH RISE BUILDINGS

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Home Building Technology Building Bye Laws

FIRE PROTECTION OF HIGH RISE BUILDINGS

High-rise buildings have unique challenges related to

fire protection such as longer egress times and

distance, evacuation strategies, fire department

accessibility, smoke movement and fire control. The

numbers of persons living on high-rise buildings are

high compared to low-rise buildings, and only

evacuation method in case of fire is the staircase. So,

the fire protections of high rise buildings have gained

significant attention worldwide.

fire-protection-high-rise-building

Thus, in case of high rise buildings, the following

provision should be made for safety of buildings from fire:

(i) National building code should be followed for fire-safety requirement of high rise structures and at

least one lift should be designed as fire-lift as defined in the Code and be installed.

(ii) At least one stair-case shall be provided as a fire staircase as defined in the National Building

Code. Provided that this shall not be applicable if any two sides of a staircase are kept totally open to

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external open air space.

(iii) Water Supply: Underground tank of the capacity of one lakh liters and two lakh liters for the

buildings situated within the municipal limit and outside of the municipal limit respectively be

invariably provided in all the high rise buildings. Water in the normal use tank should come only

through the overflow of fire tank so provided.

(iv) In high rise buildings, the internal fire hydrants shall be installed as provided in the National

Building Code or as prescribed in the Indian Standard Code of practice for installation of internal fire

hydrants in high rise buildings. The detailed plan showing the arrangement of pipe lines, booster

pumps and water-tanks at various levels shall be submitted for approval of the concerned authority

along with the plans and sections of the buildings.

(v) In case of high rise buildings, an external fire hydrant shall be provided within the confines of

the site of the building and shall be connected with Municipal Water mains not less than 4″ in

diameter. In addition, fire hydrant shall be connected with Booster Pump from the static supply

maintained on site.

(vi) In case of high rise buildings separate electric circuits for lift installation, lighting of passages,

corridors and stairs and for internal fire hydrant system shall be provided.

(vii) All the requirements under the above regulations shall be clearly indicated on plans duly signed

by the owner and the person who has prepared the plans. The Competent Authority may direct the

owner to submit such further drawings as may be necessary to clarify the implementation of the

provisions of the above regulations.

(viii) Every building having a height of more than 25 Mts. shall be provided with diesel generators

which can be utilized in case of failure of the electricity.

(ix) The standard of National Building Code must be adopted fully in providing stair-case and alarm

system.

(x) There should be Provision of dry-powder fire extinguisher to the extent of two on each floor with

a capacity of 5 kgs, in all the high rise buildings.

FLOORING AND FALSE FLOORING

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Home Building Technology Building Materials

FLOORING AND FALSE FLOORING

FLOORING AND FALSE FLOORING

Flooring is essentially required for any building. For a

building to look good it is very much necessary that

proper flooring pattern is selected. While deciding the

flooring pattern one must also consider the function

of the particular space. For example flooring pattern

used for kitchen of a house may not be suitable for

bedroom of the same house. Similarly flooring

pattern for exterior use and interior use are also

different. For example flooring which may be used in

courtyard of building or house may not be suitable

for the living room or dinning room of the same

building.

For flooring various types of material are available. Considering the need one may the select any of

the options available.

Flooring may be broadly classified into four:-

1. Tiles

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2. Stones

3. Wooden. Flooring

4. I.P.S. Flooring

Apart from this technology has started exploring new possibilities into world of flooring like glass

flooring which we did not thought of earlier days is now possible.

Tiles may be again classified into three major groups

1. Ceramic / Glazed Tiles

2. Porcelain Tiles

3. Vitrified Tiles

Stones:-

Stones are available of various shapes and size and each have different characteristics.

Here we list few of the stones

1. Kadappa Stone

2. Kota Stone

3. Dholpur Stone

4. Marble

5. Sandstone

6. Jaisalmer

7. Granite

Most of the stones are known from the place where they are available. Kota stone is available from

Kota in Rajasthan, Dholpur Stone from Dholpur, Jaisalmer stone from Jaisalmer etc.

Stones such as Jesalmer, Granite and Marble are available with different texture and colour. Their

rate depends according to their properties and texture. Generally flooring pattern and material

depends upon the budget of the building. Though it does not mean that if the budget for the flooring

is high it would result into good flooring. For flooring to be aesthetically appealing and functionally

workable proper selection of the material and proper installation of the flooring plays an important

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role.

WOODEN FLOOR

Apart from Stones and Tiles another flooring pattern is wooden floor. Wooden floor looks

aesthetically good. “PERGO” is the company name which has been into the business of wooden

flooring since years and has done a great job. Wooden flooring is quite flexible. Even if any of

wooden piece breaks or damages, it’s simple to replace it.

I.P.S. FLOOR

It is traditional Indian style of flooring. It is a simple flooring made out of cement. It’s done on site.

The cement paste is applied on the floor similar to the plastering of the wall. Then required pattern

or grids is embossed on it with rope. This is the cheapest type of flooring.

GLASS FLOORING

Apart from these, technology has become such that the wildest thing which could not been thought

of 10 years ago is now possible with the help of technology. One such example of it is GLASS

FLOORING.

Apart from flooring glass can also be used in Staircases.

clip_image001

Figure: Wooden flooring

Figure: Tile flooring

FALSE FLOORING

False Flooring is flooring used for buildings with high service requirement mostly offices which carries

high amount of cables etc. and sometimes Air-conditioner, water supply pipes. Additional structural

support and lighting are often provided when a floor is raised enough for a person to crawl or even

walk beneath.

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This type of floor consists of gridded metal frame work or understructure of adjustable-height legs

(“called Pedestal”) that provide support for individual floor panels, which are usually by 2 X 2 feet or

60 X 60 cms in size. The height of the legs/pedestals is dictated by the volume of cable and other

services provided beneath, but typically arranged for clearance of at least six inches or 15cms.

The panels are normally made of steel-clad particle board or a steel panel with a cementitious

internal core. There are a variety of flooring finishes to suit the application such as carpets, high

pressure laminates, marble, stone, and anti-static finishes for use in computer rooms and

laboratories.

Many modern computer and equipment rooms employ an under-floor cooling system to ensure even

cooling of the room with minimal wasted energy. Cooled air is pumped under the floor and dispersed

upward into the room through regularly spaced diffuser tiles or through ducts directed into specific

equipment.

Figure: False flooring

FORECASTING CONSTRUCTION DURATION

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Home Construction Construction Management

FORECASTING CONSTRUCTION DURATION

Forecasting construction duration in a project can be

achieved by many means and depends on the stage

of construction planning. Forecasting construction

duration informs the project owner to allow the

contractor to complete the work within given time.

On the other hand, the contractor could prepare

realistic and practical detailed schedule at the

minimum costs within the limited time frame.

Definitions

Construction duration can be defined as one or a

combination of the following:

1) The construction duration arising from critical path in which duration for items of work or

activity in sequence cannot be reduced further (Barrie and Paulson, 1992).

2) Duration means the time required to complete a specified task or activity. And, construction

duration is the time determined by the owner’s needs to occupy, utilize, or rent the completed

space of the project (Callahan et al., 1992).

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3) Construction duration is a duration resulting from an examination of one or more methods of

carrying out the works on the basis of minimum cost, it is usually estimated in the first instance for

normal condition (Pilcher, 1992).

4) Construction duration refers to a given time to execute and complete item(s) of work using

all project information and resources within an estimated or predicted cost (Kwaku, 1994).

5) Construction time can be defined as the elapsed period from the commencement of site

works to the completion time of building to the client. It is usually specified prior to the

commencement of construction (Nkado, 1995).

In this research, construction duration is defined as the time frame given by the owner for the

contractor to complete the project under normal work conditions, normal practice of construction,

and based on the minimum costs. It starts when the contractor receives the instruction to proceed

and ends at the completion of construction works on site. It also includes delays caused by

unanticipated circumstances, e.g. alteration of works (changed conditions and change orders), extra

works, supply of materials, location, weather, and site work conditions. Major changes that after the

scope of work significantly are not included.

Scheduling and Schedulers

Control of construction duration needs a clear systematic plan and commitment on the part of the

people involved (McNulty, 1982). The systematic plan is known as schedule. The scheduling is the

determination of the timing of activities and follows logically from the planning process (Callahan et

al., 1992). It is normally used for controlling construction duration (Callahan et al., 1992). To both

the owner and contractor, scheduling plays an important role in financial proposal and budgeting

(Peurifoy and Ledbetter, 1985; Kaka and Price, 1991). The schedule is prepared by the scheduler

and/or planner. In preparing a schedule, the scheduler or planner may meet or discuss with some

people for crucial information, e.g. estimator, manager, superintendent, sub-contractor, architect,

engineer, owner, and materials’ suppliers (Callahan et al. , 1992). They may need to study the

contract, drawings, specification, and perhaps, conduct site reconnaissance. Further, they need to

know about manpower and productivity. (Callahan et al. , 1992; Pilcher, 1992). Apart from the

schedule, it is also necessary to prepare systematic monitoring to provide early warning of restraints

as well as imaginative action to overcome them (McNulty, 1982).

Nowadays, computers may assist the scheduler or planner by storing and sorting the information, as

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well as performing mathematical calculations but they do not provide the intellectual direction

(Callahan et al., 1992). Human skill and experience are still necessary, i.e. the scheduler or planner

may use experience of similar projects in estimating the construction duration (Pilcher, 1992). The

scheduler or planner may use their judgement according to various constraints, e.g. location and

access, weather, space and site work conditions, complexity of the project, quality of workmanship,

delivery of materials, and economic or marketing conditions (Pilcher, 1992).

Forecasting Construction Duration

1. Inputs required:

The basic inputs for project scheduling are:

1) contract;

2) drawings;

3) specification;

4) resources (materials, manpower and productivity); and

5) other constraints, e.g. site conditions and weather (Burgess and White, 1979; Fisk, 1982;

McNulty, 1982; Peurifoy and Ledbetter, 1985; Ashworth, 1988; Barrie and Paulson, 1992;

Callahan et al., 1992; Pilcher, 1992).

The contract may clearly specify the completion date. Therefore, the scheduler or planner may

use this time frame to prepare the schedule together with other factor constraints. First, it is

usual to prepare the schedule for normal conditions by assuming one or more methods of

carrying out the works on the basis of minimum cost (Nkado, 1992; Pilcher, 1992). When it is

necessary to shorten the duration for an activity or a project, crashing may be done, e.g.

increase manpower and overtime working. This process leads to increase in construction cost

(Puerifoy and Ledbetter, 1985; Barrie and Paulson, 1992; Pilcher, 1992).

Drawings contain physical features of the project: 1) function; 2) height; 3) systems (e.g.

plumbing, fire fighting, and lighting); and complexity (Ireland, 1985; Ashworth, 1988; Pilcher,

1992; Nkado, 1992). In other words, the information on the drawings is presented in form of

dimensions and descriptions (Ashworth, 1988). Materials and installed equipment for the

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project, as well as the plant and construction equipment can also be known from the drawings

(Ashworth, 1988; Peurifoy and Ledbetter, 1992). Meanwhile, the contract may specify the

constraints of work, e.g. construction cost, duration, payment, inspection, method or

conditions of works, delays, and damages. In addition, the specification may address the

quality of materials, workmanship, and method of working (Barrie and Paulson, 1992).

2. Resource scheduling

The scheduler or planner has to allocate the resources, i.e. materials and manpower (or

working team) to each activity or task at the proper time they are needed. Thus, the resource

schedule deals with levelling and allocation of all necessary resources (Peurifoy and Ledbetter,

1985). The former smoothes out the peaks and valley in resource use within the project

duration. The latter determines the shortest project duration consistent with the limited

resources.

4. Other judgements

They also have to provide timing for preliminary works, e.g. construction plant, and

mobilization (Peurifoy and Ledbetter, 1985). This often includes time for remedial works and

site clearing after completing the construction.

Site reconnaissance enables the scheduler or planner to adjust the schedule against various

constraints, e.g. location and access, weather, space and site work conditions, complexity of

the project, quality of workmanship, delivery of materials, and economic or marketing

conditions (Barrie and Paulson, 1992; Pilcher, 1992).

Some Methods for Project Scheduling

There are many forms of schedules, e.g. Gantt or bar chart, Critical Path Method (CPM), and Program

Evaluation and Review Technique (PERT). Each has its own advantages, disadvantages, and

application areas for which it is most appropriate. They are means of visual presentation of a

construction program (Pilcher, 1992), and used for project planning, management, and control

(Burgess and White, 1979; Fisk, 1982; McNulty, 1982; Barrie and Pualson, 1992).

Gantt chart simply represents the activity and its duration by a bar. It is sometimes called Bar chart.

Gantt or bar chart can include a great deal of anticipated and actual information for; 1) cashflow; 2)

manpower and/or manpower by trade; and 3) productivity (Barrie and Paulson, 1992; Callahan et

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al., 1992).

In CPM scheduling, a construction project is sub-divided into several activities. An activity is a single

work step that has a recognizable beginning and finishing or ending (Callahan et al., 1992). In other

words, the activity is a time-consuming task. The basis of CPM is network diagram, i.e. which needs

nodes and arrows. It deals with four aspects: 1) activities identification; 2) logical sequence,; 3)

network construction; and 4) allocation of resources (Barrie and Paulson, 1992). Callahan et al.

(1992) divided the development of CPM schedule into six phases:

1) understanding the project;

2) conceptual approach definition;

3) physical creation of the schedule;

4) computerization;

5) refinement; and

6) reproduction.

Further, physical creation of CPM scheduling is divided into eight steps: 1) select software;

2) divide project into several activities and sub-networks;

3) develop responsibility code;

4) develop information code;

5) develop specific sub-networks;

6) build or plot the logic diagram;

7) numbering the activities; and

8) linking the sub-networks together.

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The longest interconnected path of activities through the network called “critical path” becomes the

project duration. On the critical path means that the duration for items of work or activity on the

sequence cannot be reduced further without paying extra costs (Peurifoy and Ledbetter, 1985; Barrie

and Paulson, 1992).

PERT is like CPM scheduling . It uses logical diagram to analyze performance time. It overcomes

difficulties associated with duration of activities which could not be estimated reliably. PERT enables

the scheduler to estimate the most probable project duration and the probability that the project or

any portion of the project will complete at particular time. PERT focuses on events or nodes, called

event-oriented. Unlike the CPM, it requires three estimates of duration for each activity: 1) optimistic

(high productivity); 2) pessimistic (low productivity); and 3) most likely duration (Peurifoy and

Ledbetter, 1985; Barrie and Paulson, 1992; Callahan et al., 1992; Pilcher, 1992).

Factor Affecting Construction Duration

The following are some factors affecting construction duration and its estimate.

1. Size of project

Size of the project can be represented in terms of functional or floor area, i.e. in ft , or m .

The larger the building size, the more complex the construction, thus needing longer duration

to complete (Sadashiv, 1979; Ireland, 1985; Ashworth, 1988; Pilcher, 1992; Nkado, 1992).

2. Function

Function implies type of building and required engineering systems, e.g. plumbing, fire

fighting, and lighting (Ashworth, 1988; Pilcher, 1992). It is an important facet in designing of

construction project (Ashwoth, 1988). Function of a building implies business target that the

building serves. It can be considered as qualitative variables, e.g. office, retail, and other

buildings (Nkado, 1992).

3. Height

Height of building, represented by number of floors (or storeys) affects the construction

duration (Sadashiv, 1979; Ireland, 1985). The height of building indicates construction

technique, major equipment used, and construction sequence (Sadashiv, 1979; Callahan et al.,

1992).

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4. Complexity

Complexity implies unfamiliarity with work (Pilcher, 1992). The complexity of building impacts

the form of construction, i.e. building frame, foundation, and systems (Ireland, 1985;

Ashworth, 1988). Complexity can be represented in form of construction equipment, method

and sequence (Sadashiv, 1979; Callahan et al., 1992; Chan and Kumaraswamy, 1995).

5. Quality

Quality can be classified by variables or attributes, i.e. appearance, strength, stability,

materials used, performance finish. Appearance of the building, e.g. external facing is one

aspect of quality (Ashworth, 1988). Sadashiv (1979) considered number of major finishing

works in duration forecasting instead of a defined quality index.

6. Location

The location of the building has a significant effect on the construction duration (Chan and

Kumaraswamy (1995). It reflects restrictions or easements that exist and availability of

services (Burgess and White, 1979). It effects supply of resources, e.g. materials, and

equipment (Sadashiv, 1979). Consequently, it also effects the use of major equipment

(Sadashiv, 1979), and productivity on site (Callahan et al., 1992).

There are other possible factors affecting the construction duration, e.g. construction planning

(Sadashiv, 1979; Ireland, 1985), design-construction interface coordination (Ireland, 1985), dispute

per unit of time (Ireland, 1985). Type and/or variation to the contract refers to risk allocation

management structure and payment modalities (Burgess and White, 1979; Ireland, 1985; Chan and

Kumaraswamy, 1995). By contrast, Walker (1994) concluded that client related factors have more

significant affect on speed of construction, or construction duration, than the contract type. Callahan

et al. (1992) pointed out that quality of supervision, labour training and motivation, can also be

affecting factors. Al Tabtabai et al. (1997) developed the models for expert judgment in forecasting

construction project completion. The factors are: 1) performance of management; 2) cash flow

situation; 3) material and equipment availability; 4) labour productivity; 5) weather and

environment influences; 6) rework, extra work, and work difficulty; 7) percentage of work

completed; and 8) trend in schedule variance.

Project Delays and their Causes:

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Project duration is normally specified by the owner. The completion and operation of many buildings

are restricted as they are seasonal in nature, e.g. a school must open in September, a retail outlet

must open for booking in August to meet the Christmas sale season, and an apartment must open in

May to reach the spring market (McNulty, 1982). Construction duration affects the financial interest

to the owner, e.g. selling price, and on-site management. Then, the contractor is traditionally

responsible for the detailed planning and scheduling to ensure the completion of the project within

the owner’s time frame. However, the actual construction duration consist of two parts:

1) contract time; and

2) delay.

Delay is the time during which some parts of construction project has been extended or not

performed because of unanticipated circumstances (Barrie and Paulson, 1992). When necessary, the

contractor may need to allocate an additional budget for corrective actions to maintain the schedule,

otherwise, it may cause liquidated damages charges against the contractor for failure to meet the

owner’s requirements (Fisk, 1982; McNulty, 1982).

Alteration of working drawing is one of a major factor affecting the construction duration, i.e. it may

cause a delay beyond the contract time (Sadashiv, 1979; Chan and Kumaraswamy 1995). Barrie and

Paulson (1992) summarized causes of delay into four areas:

1) changed conditions and change orders;

2) extra works;

3) owner or his/her agent; and

4) third party contractors.

However, other possible delays may result from location, weather, site work conditions, labour

productivity, sub-contractor, supply and delivery of materials (Burgess and White, 1979; Sadashiv,

1979; Callahan et al., 1992; Chan and Kumaraswamy, 1995).

Relationship between Cost and Time:

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There is a relationship between cost and duration (or time). In construction planning and scheduling,

alternative duration and costs for activities are always considered. For example, when it is necessary

to shorten the duration of activities or project, the cost may increase. This is called “crashing“.

Sadashiv (1979) found that some of the independent variables used in regression model for cost

forecasting also have major affects on construction duration, e.g. height, and types of major

equipment. However, he used the number of major finishing works in his duration forecasting model

instead of the quality index as used in the cost forecasting model.

Ireland (1985) found a relationship between construction time and cost. In his study, the

construction time and cost are dependent on some common independent variables:

1) construction planning during design;

2) variation to the contract; and

3) complexity of form of construction.

In addition, number of storey’s, design-construction interface co-ordination, and dispute per unit of

time also affect the construction time while architectural quality, and use of nominated sub-

contractors affect only the construction cost.

Kaka and Price (1991) found strong relationship between the cost and duration of construction

projects that can be used in contractor’s budgeting systems and corporate financial model. Investors

of project can utilize the relationship for financial appraisal and budgeting. Estimating of project cost

can be used to derive the expected duration and vice versa.

Pre-design Estimating of Project Duration:

Pre-design estimating of construction duration is important. Chan and Kumaraswamy (1995) noted

that pre-contract determination of the construction duration is essential for proper cash flow

forecasting by both the contractor and the client. It can facilitate optimal resource allocation,

financial planning, profitability and efficiency of capital flow within a pre-determined time limit.

Based on the inputs required for scheduling, all the current methods of scheduling seem to be

efficiently applied only when the detailed design is completed. Normally, the contractor must

complete this planning prior to bidding for the project (Peurifoy and Ledbetter, 1985). Without

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sufficient information, the schedule can be prepared based on only the best guess, i.e. using

experience of similar projects in estimating the construction duration (Pilcher, 1992).

Nkado (1992) established a computerized construction time information system for planning of

buildings at the early stage of design. Two key assumptions are:

1) the building team is competent and efficacious in setting up the building process and working

within local norms and organization form to bring the project to a successful completion; and

2) the frame of reference for construction times is based on the overall time consistent with the

minimum direct cost of construction to the contractor.

Al Tabtabai et al. (1997) developed the multi-regression and neural network models to capture the

decision-making procedure of project experts involved in schedule monitoring and prediction. The

models were applied to a multi-storey building under construction. They provided the convenient and

realistic generation of revised schedules at appropriate junctures during the progress of the project.

The accuracy of the models mainly depends on the soundness of the underlying expert decision, i.e.

inputs generated from judgment of the experts are not free of bias. However, they concluded that

modelling construction experience to use in future projects can help significantly in achieving project

objectives.

A model for forecasting the construction duration should be valid in application for a reasonably long

period of time without the effects from changes in price level. The price indices may not be applied

or included in the model. The model should be slightly affected by change in construction technology

in long term application. Today, the construction industry is still labour intensive. Automation which

has reduced the labour force in manufacturing industry, has not been matched in the construction

industry (Ashworth, 1988). This means

construction technology has changed only slightly over time.

Summary

A variety of methods and techniques for construction planning and scheduling exist but they are

based mainly on the completed design and details of project, e.g. Gantt chart, CPM, and PERT.

Construction schedule is normally prepared by the contractors at the time they submit bids. Without

sufficient information, the scheduling and forecasting of construction duration is based on the

experience of the planner or scheduler. A number of researches found strong relationship between

FORECASTING CONSTRUCTION DURATION

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TAGS Construction Construction Management Others

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TECHNIQUES TO RESTORE ORIGINAL STRENGTHOF STRUCTURES

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SOIL STABILIZATION WITH LIME &FLYASH

construction duration and cost. This leads to the possibility to build a model for forecasting the

construction duration at pre-design phase. The model may consist of part of variables as they are

used in the cost forecasting models. The main variables shall consist of building features, e.g.

function, structural system, height, foundation, exterior and interior finishing. Adjustment of the

construction duration by means of indices is not necessary.

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RELATED ARTICLES MORE FROM AUTHOR

FORMWORK SAFE PRACTICES CHECKLIST

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Home Building Technology

FORMWORK SAFE PRACTICES CHECKLIST

A safe practice for formwork during construction at

site is important for safety of workmen. Improper

erection of formwork can cause damage to structural

element as well as pose threat to the safety of

workmen.

Following are the safe practices checklist for

formwork:

Formwork Safety Checklistduring Design:

1. Formwork should be properly designed for the structural element considered and its working

drawing should be available at site.

2. Design of formwork should consider all the loads it will experience during casting of concrete

structural members.

3. Strength of materials used for formwork should be adequate to support structural load as well as

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FORMWORK SAFE PRACTICES CHECKLIST

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other loads imposed on it.

4. Formwork design should indicate the rate of concrete pour, height of concrete pour, temperature

and sequence and schedule of concrete pours.

5. Working drawing of formwork should have detailed dimensions including pouring pocket size,

compaction opening and cleanouts.

6. Formwork design should consider the safe bearing capacity of soil.

FORMWORK SAFE PRACTICES CHECKLIST

Formwork Safety Checklist during Construction:

Following inspection should be carried out before starting the concreting of structural member:

1. Inspection of entire formwork system for details from bottom to top of formwork for proper load

transfer in safe manner.

2. Inspection of working scaffolds, ladders, runways, ramps and crossings.

3. Maintenance of good housekeeping around working area and passage.

4. Guarding of peripheral edges and floor openings.

5. Adequate space for safe working.

6. Safety training of workmen involved in formwork and concreting works.

7. Use of all personal protective equipment (PPEs).

8. Formwork, rigging inserts and connections checked for correct installation and periodically checked

for wear and correct position.

9. Removal of all unused and hanging forms, loose materials etc. stored on exposed floors.

FORMWORK SAFE PRACTICES CHECKLIST

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10. Inspection of all props and shores for adequacy to handle all the loads.

11. Removal of defective props.

12. Alignment of props such as verticality, height and spacing between props should be inspected.

13. All props should be rested on bearing plates.

14. Props should be placed on hard bearing surface.

15. Safe nailing and firm locking of clamps on adjustable props.

16. Lateral stability of formwork and complete fixity at the joint between props when one prop is

placed on the top of the other.

17. Proper bearing below the stringers and joists at points of supports.

18. De-shuttering and removal of props below concrete slabs and beams after development of

adequate strength in concrete.

19. Construction loads not placed on freshly cast slab or beams while removal of formwork or before

concrete attaining required strength.

There can be many more checklists for formwork which has not been written here. If you think any

addition has to be made, please write those in comments.

You can also download this document for formwork safe practices

FUNCTIONS OF INGREDIENTS OF CEMENT (OPC)

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Home Building Technology Building Materials

FUNCTIONS OF INGREDIENTS OF CEMENT (OPC)

Functions Of Ingredients of Cement (OPC):

The ingredients of ordinary cement, as mentioned

above, perform the following functions:

Lime (CaO): This is the important ingredient of

cement and I s proportion is to be carefully

maintained. The lime in excess makes the cement

unsound and causes the cement to expand and

disintegrate. On the other hand, if lime is in

deficiency, the strength of cement decreases and it

causes cement to set quickly.

Silica (Si0 ): This is also an important ingredient’ of cement and it gives or imparts strength to the

cement due to the formation of dicalcium and tricalcium silicates. If silica is present in excess

quantity, the strength of cement increases but at the same time, its setting time is p. longed.

Constituents of cement

2

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FUNCTIONS OF INGREDIENTS OF CEMENT (OPC)

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TAGS Building Materials Buildings Cement

Fig: Constituents of cement

Alumina (AI 0 ): This ingredient imparts quick setting property to the cement. It acts as a flux and

it lowers the clinkering temperature. However the high temperature is essential for the formation of

a suitable type of cement and hence the alumina should not be present in excess amount as it

weakens the cement.

Calcium sulphate (CaS0 ): This ingredient is in the form of gypsum and its function is to increase

the initial setting time of cement.

Iron oxide (Fe 0 ): This ingredient imparts color, hardness and strength to the cement.

Magnesia (MgO): This ingredient, if present in small amount, imparts hardness and color to the

cement. A high content of magnesia makes the cement unsound.

Sulphur (S): A very small amount of sulphur is useful in making sound cement. If it is in excess, it

causes cement to become unsound.

Alkalis: The most of the alkalis present in raw materials are carried away by the flue gases during

heating.

2 3

4

2 3

GOOD CONSTRUCTION PRACTICES AND TECHNIQUES TO PREVENT STRUCTURAL DAMAGE

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Home Work Procedures Concrete

GOOD CONSTRUCTION PRACTICES ANDTECHNIQUES TO PREVENT STRUCTURALDAMAGE

Good construction practices and techniques should be

followed to prevent occurrence of structural damages

that may occur during occupancy and with age of the

structure. A structure has to go through different

stages in construction process. Each and every stage

of construction is important to make sure that the

structure being constructed will not experience

damage under any general circumstances.

Development of cracks in structure is the first sign of

damage. Structural damage does not only reduces

strength of the structure but it may also make it unfit

for use to the extent that the structure collapses. It is

very important for the civil engineers to ensure good

construction practices are followed at every stage of construction to prevent structural damage and

failure of the structure.

Following are the good construction practices and techniques that shall be followed for good

quality and durable construction of structure:

1. Masonry work:

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GOOD CONSTRUCTION PRACTICES AND TECHNIQUES TO PREVENT STRUCTURAL DAMAGE

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Masonry work in a structure should be carried out in uniform levels at all parts of the structure to

prevent differential settlement of foundation due to differential loading. This will prevent the

cracking of masonry walls and also other structural elements. Difference in the height of masonry

in different parts of a building should normally not exceed 1m any time during construction.

Masonry work should be properly cured for a minimum period of 7 to 10 days.

Masonry works on any RCC elements such as RCC Slab and beams should not be started till

minimum of 2 weeks after striking off the shuttering.

2. Concrete work:

In reinforced concrete members such as cantilever beams and slabs which are liable to deflect

appreciably under load, removal of centering and imposition of load should be deferred at least

one month so that concrete gains sufficient strengths before it bears the load.

Curing of any concrete member should be done for a minimum period of 7 to 10 days and

terminated gradually so as to avoid quick drying.

Concrete work in very hot and windy climate should be avoided, and in case it is not avoidable

then precautions shall be taken to keep the temperature of fresh concrete down and to prevent

quick drying of concrete. Following steps should be taken to keep the temperature of freshly

prepared concrete down:

– Aggregate and mixing water should be shaded from direct sun.

– Part of mixing water may be replaced by pounded ice.

– As far as possible concreting should be done in early hours of the day.

Re-trowelling the concrete surface slightly, before its initial setting to mitigate plastic shrinkage

cracks

3. RCC frame work:

As far as possible frame work should be completed before starting work of panel walls for cladding

and partitioning.

GOOD CONSTRUCTION PRACTICES AND TECHNIQUES TO PREVENT STRUCTURAL DAMAGE

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Work of construction of panel walls and partition should be deferred as much as possible and

should proceed from top to down ward.

When partition walls are to be supported on floor beam or slab upward camber should be

provided in floor slab/beam to counter act deflection.

Horizontal movement joint should be provided between top of panel wall and soffit of beam and

when structurally required little support to the wall should be provided at the top by using

telescopic anchorage or similar arrangement. Horizontal movement joint between top of wall and

soffit of beam/slab shall be filled which some compressible jointing material.

If door opening is to be provided in partition wall a center opening is more preferable than off

center opening.

Light re-vibration of concrete shall be done, before it has set, for the member and section prone

for plastic settlement cracks i.e. narrow column and walls, at change of depth in section.

4. Plastering:

When plastering is to be done on masonry, mortar joints in masonry should be raked out to 10

mm depth while the mortar is green. Plastering should be done after masonry has been properly

cured and allowed to dry so as to undergo initial shrinkage before plaster.

For plastering on concrete background, it should be done as soon as feasible after removal of

shuttering by roughing of concrete surface where necessary by hacking, and applying neat cement

slurry on the concrete surface to improve the bond.

When RCC and brick work occurs in combination and to be plastered, then sufficient time (at least

1 month) shall be allowed for RCC and brickwork to undergo initial shrinkage and creep before

taking up plaster work. In such case either groove shall be provided in the plaster at the junction

or 10cm wide strip of metal mesh or lathing shall also be provided over the junction to act as

reinforcement.

5. Concrete and terrazzo floor:

Control joint should be provided in the concrete and terrazzo floor either by laying floors in

alternate panels or by introducing strips of glass, aluminium or some plastic material at close

interval in grid pattern.

When flooring is to be laid on RCC slab, either a base course of lime concrete should be provided

between the RCC slab and the flooring or surface of slab should be well roughened, cleaned and

primed with cement slurry before laying of floor.

5. RCC Lintels:

GOOD CONSTRUCTION PRACTICES AND TECHNIQUES TO PREVENT STRUCTURAL DAMAGE

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Bearing for RCC lintels should be on the liberal side when spans are large so as to avoid

concentration of stress at the jambs.

6. RCC roof slab:

The top of the slab should be provided with adequate insulation or protective cover together with

some high reflectivity finish cover to check the thermal movement of the slab and consequent

cracking in supporting wall and panel/partition wall.

In load bearing structure, slip joint should be introduced between the slab and supporting/cross

walls. Further either the slab should project for some length from the supporting wall or the slab

should rest only on part width of the wall as shown in figure below:

Bearing of RCC Slab on Masonry Wall

Fig.1: Constructional detail of bearing of RCC roof slab over a masonry wall

On the inside, wall plaster and ceiling plaster should be made discontinuous by a groove of about 10

mm.

For introducing the slip joint, the bearing portion of supporting wall is rendered smooth with plaster

(preferably with neat cement finish), which is then allowed to set and partly dry. Thereafter either it

is given thick coat of whitewash, or 2 to 3 layers of tarred paper is placed over the plaster surface,

before casting of slab.

7. Provision of glazed, terrazzo or marble tile on vertical surface:

Before fixing of these tiles on vertical surface background component should be allowed to undergo

movement due to elastic deformation, shrinkage & creep otherwise tiles are likely to crack and

dislodged.

8. RCC work in exposed condition:

For RCC work in exposed condition i.e. sunshades, balconies, canopies, open verandah etc., to

prevent shrinkage cum contraction cracks, adequate quantity of temperature reinforcement shall be

provided. In such condition quantity shall be increase by 50 to 100 % of the minimum amount

prescribed.

GOOD CONSTRUCTION PRACTICES AND TECHNIQUES TO PREVENT STRUCTURAL DAMAGE

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9. Finish on wall:

Finishing items i.e. distemper and painting etc. should be carried out after the plaster has dried and

has under gone drying shrinkage.

10. Pace of construction:

The construction schedule and the pace of construction should be regulated to ensure :

All items of masonry are properly cured and allowed to dry before plastering work is done, thus

concealing the cracks in masonry in plaster work. Similarly plaster work should be cured and

allowed to dry before applying finishing coat. So as to conceals the cracks in plaster under finish

coat.

In case of concrete work before taking masonry work either over it or by its side, the most of the

drying shrinkage, creep and elastic deformation of concrete should be allowed to take place, so as

to avoid cracks in masonry or a the junction of masonry and concrete.

11. Provision of reinforcement for thermal stresses:

To control the cracks in concrete due to shrinkage as well as temperature effect, adequate

temperature reinforcement shall be provided. This temperature reinforcement is more effective if

smaller diameter bars and the deformed steel is used than plain reinforcement.

12. Extension of existing building:

(a) Horizontal extension: Since foundation of an existing building undergoes some settlement as

load comes on the foundation, it is necessary to ensure that new construction is not bonded with the

old construction and the two parts are separated by a slip or expansion joint right from bottom to

top. Otherwise, when the newly constructed portion undergoes settlement, an unsightly crack may

occur at the junction.

Care should also be taken that in the vicinity of the old building, no excavation below the foundation

level of that building is carried out.

When plastering the new work, a deep groove should be formed separating the new work from the

old.

GOOD CONSTRUCTION PRACTICES AND TECHNIQUES TO PREVENT STRUCTURAL DAMAGE

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When it is intended to make horizontal extension to a framed structure later on than the twin column

with combined footing shall be provided at the time of original construction itself as under:

b) Vertical extension: When making vertical extension to an existing building (that is adding one or

more additional floors) work should be proceeded at a uniform level all round so as to avoid

differential load on the foundation. In spite of this precaution, however, sometimes cracks appear in

the lower floors (old portion) at the junction of RCC columns carrying heavy loads and lightly loaded

brick masonry walls due to increase in elastic deformation and creep in RCC columns. Such cracks

cannot be avoided.

Renewal of finishing coats on old walls of old portion should be deferred for 2 or 3 months after the

imposition of additional load due to new construction so that most of the likely cracking should take

place before finish coat is applied thus concealing the cracks.

13. Rich cement treatment on external walls:

When it is proposed to give some treatment on external walls of some rich cement based material

i.e. artificial stone finish, terrazzo etc., the finish should be laid in small panels with deep grooves in

both directions.

14. Movement joints:

To mitigate/relieve the magnitude of stresses due to thermal movement and shrinkage movement

joints i.e. Expansion joint, Control joint and Slip joint shall be provided in the structure.

15. Filling in plinth:

Filling in plinth should be done with good soil free from organic matter, brickbats and debris etc. It

should be laid in 25 cm thick layers, well watered and compacted to avoid possibility of subsequent

subsidence and cracking of floors.

HOW COARSE AGGREGATES AFFECT MIX DESIGN?

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Home Building Materials Aggregates

coarse-aggrgates-mix-design

HOW COARSE AGGREGATES AFFECT MIXDESIGN?

Coarse Aggregate Properties affecting Mix

Design Strength

Maximum size of coarse aggregate:

Maximum size of aggregate affects the workability

and strength of concrete. It also influences the water

demand for getting a certain workability and fine

aggregate content required for achieving a cohesive

mix.

For a given weight,

higher the

maximum size of aggregate, lower is the surface area of coarse aggregates and vice versa. As

maximum size of coarse aggregate reduces, surface area of coarse aggregate increases. Higher the

surface area, greater is the water demand to coat the particles and generate workability.

Smaller maximum size of coarse aggregate will require greater fine aggregate content to coat

particles and maintain cohesiveness of concrete mix. Hence 40 mm down coarse aggregate will

require much less water than 20 mm down aggregate. In other words for the same workability,

40mm down aggregate will have lower water/cement ratio, thus higher strength when

compared to 20mm down aggregate. Because of its lower water demand, advantage of

higher maximum size of coarse aggregate can be taken to lower the cement consumption.

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HOW COARSE AGGREGATES AFFECT MIX DESIGN?

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Maximum size of aggregate is often restricted by clear cover and minimum distance between the

reinforcement bars. Maximum size of coarse aggregate should be 5 mm less than clear cover

or minimum distance between the reinforcement bars, so that the aggregates can pass

through the reinforcement in congested areas, to produce dense and homogenous concrete.

It is advantageous to use greater maximum size of coarse aggregate for concrete grades up to M 35

where mortar failure is predominant. Lower water/cement ratio will mean higher strength of mortar

(which is the weakest link) and will result in higher strength of concrete. However, for concrete

grades above M40, bond failure becomes predominant. Higher maximum size of aggregate, which

will have lower area of contact with cement mortar paste, will fail earlier because of bond failure.

Hence for higher grades of concrete (M40 and higher) it is advantageous to use lower maximum size

of aggregate to prevent bond failure.

Grading of coarse aggregate:

The coarse aggregate grading limits are given in IS 383 – 1970 – table 2, Clause 4.1 and 4.2 for

single size aggregate as well as graded aggregate. The grading of coarse aggregate is important to

get cohesive & dense concrete. The voids left by larger coarse aggregate particles are filled

by smaller coarse aggregate particles and so on. This way, the volume of mortar (cement-sand-

water paste) required to fill the final voids is minimum. However, in some cases gap graded

aggregate can be used where some intermediate size is not used. Use of gap-graded aggregate may

not have adverse effect on strength. By proper grading of coarse aggregate, the possibility of

segregation is minimised, especially for higher workability. Proper grading of coarse aggregates also

improves thecompactability of concrete.

Shape of coarse aggregate:

CoAse aggregates can have round, angular, or irregular shape. Rounded aggregates because of

lower surface area will have lowest water demand and also have lowest mortar paste requirement.

Hence they will result in most economical mixes for concrete grades up to M35. However, for

concrete grades of M40 and above (as in case of max size of aggregate) the possibility of bond

failure will tilt the balance in favour of angular aggregate with more surface area. Flaky and

elongated coarse aggregate particles not only increase the water demand but also increase the

HOW COARSE AGGREGATES AFFECT MIX DESIGN?

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tendency of segregation. Flakiness and elongation also reduce the flexural strength of concrete.

Specifications by Ministry of Surface Transport restrict the combined flakiness and elongation

to 30% by weight of coarse aggregates.

Strength of coarse aggregate:

Material strength of coarse aggregate is indicated by crushing strength of rock, aggregate crushing

value, aggregate impact value, aggregate abrasion value. In Maharashtra the coarse aggregates are

made of basalt rock, which has strengths in excess of 100 N/mm2. Hence aggregates rarely fail in

strength. The IS limits for above tests are given below:

• Aggregate Crushing value

• Aggregate Impact value

• Aggregate abrasion value

Aggregate Absorption:

Aggregate can absorb water up to 2 % by weight when in bone dry state, however, in some cases

the aggregate absorption can be as high as 5%. Aggregate absorption is used for applying a

correction factor for aggregates in dry condition and determining water demand of concrete in

saturated surface dry condition.

HOW TO MAKE A BUILDING GREEN

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Home Building Technology

HOW TO MAKE A BUILDING GREEN

What is a Green Building?

The concept of a green building was developed in the

1970s in response to the energy crisis and people’s

growing concerns about the environment.

A Green Building, also known as a sustainable

building, is a structure that is designed, built,

renovated, operated, or re-used in an ecological and

resource efficient manner.

Sustainable development is maintaining a delicate balance between the human need to improve

lifestyles and feeling of well-being on one hand, and preserving natural resources and ecosystems,

on which we & future generations depend

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HOW TO MAKE A BUILDING GREEN

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Objectives of a green building:

Protecting occupant health

Improving employee productivity

Using energy, water and other resources more efficiently

Reducing overall impact to the environment

Optimal environmental and economic performance

Satisfying and quality indoor spaces

Considerations of a green building:

Control erosion to reduce negative impacts on water and air quality

Reduce pollution and land development impacts from automobile use

Limit disruption of natural water hydrology by reducing impervious cover, increasing on-site

infiltration and managing storm water run-off

Encourage and recognize increasing levels of self supply through renewable technologies to reduce

environmental impacts associated with fossil fuel energy use

Provide a high level of individual occupant control of ventilation and lighting systems to support

good health, better productivity and a comfortable atmosphere

Provide a connection between indoor spaces and outdoor environment through the introduction of

sunlight and views into the occupied areas of the building.

How to make a building green:

Building design

Orientation

Building insulation (walls of AEC block and roof with over deck insulation and roof lawn)?

Window sizing

Window shading (fixed overhangs)?

Glass selection

Envelope efficiency measures contributed to 12% savings over base case

System design

Energy efficient lighting (CFLs , efficient tube lights and electronic ballasts)?

Daylight sensing (90% lighting energy savings)?

Efficient chillers, Variable air volume systems.

Wind towers for pre cooling of fresh air.

Lighting efficiency measures contributed to 15% savings over base case and HVAC efficiency

measures contributed 20% savings over base case.

HOW TO MAKE A BUILDING GREEN

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Constitutes a green building

A) Sustainable Site:

Appropriate site selection.

Effective use of nature.

Soil erosion control.

B) Water use efficiency:

Capture storm water from impervious areas of the building for ground water re-charge or reuse.

Do not use potable water for landscape irrigation. Use recycled water/storm water.

Install moisture denser on plants for water conservation.

Use recycled water for toilet flushing.

Use ultra high efficiency water fittings and controls.

Monitor water consumption through on-line controls.

C) Energy efficient and eco-friendly equipment:

Design orientation of the building to get maximum day-lighting.

Use green wall and green roof to avoid heat gain into the building.

Adopt spectrally natural glass materials such that it reduces heat gain, minimize lighting of

landscape features.

Use of energy efficient goods

Use zero CFC base refrigerants in refrigeration and air-conditioning system.

Use of renewable energy to reduce environmental impacts associated with fossil fuel energy use.

Establish Baseline data for energy consumption

D) Eco-friendly building materials and resources:

Recyclable and Salvage materials.

Material from local sources mitigating / reducing environmental impact.

Impact of manufacturing and transportation.

Salvage controls.

Material pollutant management

Health Hazard management of workers on site.

Material storage methodologies.

HOW TO MAKE A BUILDING GREEN

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TAGS Buildings Green Buildings Green Roofs

Waste management.

E) Indoor air quality:

Distribution channels for air intake movement and exhaust

Climate and pollution monitoring systems.

Elimination of chemically toxic materials and devices.

Maintenance of optimum temperature and humidity.

F) Energy system management:

30% to 40% saving in operation costs.

Alternative energy system design

Optimization of Conventional Energy.

Building management, control and monitoring systems.

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INSULATING CONCRETE FORMWORK

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Home Building Technology

INSULATING CONCRETE FORMWORK

Insulating concrete formwork (ICF) is a building

system that uses lightweight formwork (made from

an insulating material) to support concrete walls

whilst they are being cast in-situ and which is then

left in place as insulation.

Insulating concrete formwork

Used on the continent and in North America for many

years, ICF has proved to be robust, cost effective

method of constructing of variety of building types –

from houses and basements to multi-storey cinemas

and commercial buildings.

How is it used in practice?

Insulated concrete formwork consists of twin-walled expanded polystyrene panels that are stacked

together to create the permanent formwork used to contain the ready-mixed concrete for the walls.

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The insulated formwork remains in place to provide complete thermal insulation to the walls of the

finished building. It also provides a uniform surface ready for direct application of most finishes and

proprietary cladding systems. Many insulated concrete formwork systems also incorporate their own

flooring system.

Design Considerations:

The blocks that make up the insulating formwork are manufactured in a variety of shapes and

component types, creating limitless design opportunities. For example, features such as bay

windows and arches can be generated without having to resort to specialist products. In addition,

floors can be constructed using ICF components.

Any type of foundation, flooring, partition, stair or roofing system is compatible with ICF

construction.

ICF provides an easy means of achieving high standards of structural, energy, fire and acoustic

performance.

The exterior of the building can be clad in any finish the architect requires including masonry,

brick slips, render tiles, curtain walling and weather boarding. Internally, plaster or dry lining is

applied directly to the face of the expanded polystyrene formwork.

ICF advantages for the builder:

ICF is quick and easy to use without the need of skilled tradesman. In fact, any builder can

quickly erect an ICF structure since the lightweight units are easier to handle than traditional

materials. Typically an experienced team of four can erect and concrete the walls of a three-

bedroomed bungalow in a day, significantly reducing the contract program.

The low labour and reduced need for skilled tradesman result in more efficient use of increasingly

scarce construction workers. Also, with the speedy construction of watertight building envelope,

internal services and finishings can progress independently of external cladding.

Service ducts and utilities can be pre-installed within the concrete core or chased into the

INSULATING CONCRETE FORMWORK

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expanded polystyrene using a router of hot-wire cutter.

ICF components and temporary bracing systems are delivered as lightweight portable packs,

which do not require mechanical handling or the use of special tools.

Just-in-time deliveries and direct placement of ready-mixed concrete reduces waste and site

storage facilities. Also, the energy-efficient building allows downsizing of the boiler.

ICF Advantages for the occupier

The occupants benefit from low running expenses, as the energy-efficient building costs less to

heat. In fact, some houses need no heating other than that provided by solar energy.

The ICF insulation reduces impact sound, while the concrete core provides a solid mass to reduce

airborne noise. This makes the system ideal for party wall construction.

All ICF materials are inert, giving no toxic fumes. Also, the building maintains an even

comfortable temperature, and air quality is essentially controlled – good news for those with

asthma or other allergies. There are no problems with condensation, mould or mildew.

All expanded expanded polystyrene materials used in ICF buildings are treated with fire retardant,

thus giving all ICF systems appropriate fire certifications. All mortgage lenders, insurance

companies and planning authorities accept ICF certification.

Article by: Jamshaid Sawab

JOINTS IN CONCRETE CONSTRUCTION

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JOINTS IN CONCRETE CONSTRUCTION

Joints in concrete building construction are

construction joints, expansion joints, contraction

joints and isolation joints. They prevent cracking of

concrete. Types of joints in concrete are described

below:

Construction Joints:

Construction joints are placed in a concrete slab to define the

extent of the individual placements, generally in conformity

with a predetermined joint layout.

They must be designed in order to allow displacements

between both sides of the slab but, at the same time, they

have to transfer flexural stresses produced in the slab by external loads.

Construction joints must allow horizontal displacement right-angled to the joint surface that is normally caused by

thermal and shrinkage movement. At the same time they must not allow vertical or rotational displacements. Figure

1 summarizes which displacement must be allowed or not allowed by a construction joint.

clip_image001

Expansion joint

The concrete is subjected to volume change due to many reasons. So we have to cater for this by

way of joint to relieve the stress. Expansion is a function of length. The building longer than 45m are

generally provided with one or more expansion joint. In india recommended c/c spacing is 30m. The

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joints are formed by providing a gap between the building parts.

Contraction Joints

A contraction joint is a sawed, formed, or tooled groove in a concrete slab that creates a weakened

vertical plane. It regulates the location of the cracking caused by dimensional changes in the slab.

Unregulated cracks can grow and result in an unacceptably rough surface as well as water infiltration

into the base, subbase and subgrade, which can enable other types of pavement distress.

Contraction joints are the most common type of joint in concrete pavements, thus the generic term

“joint” generally refers to a contraction joint. Contraction joints are chiefly defined by their spacing

and their method of load transfer. They are generally between 1/4 – 1/3 the depth of the slab and

typically spaced every 3.1 – 15 m

Isolation Joints

Joints that isolate the slab from a wall, column or drainpipe

Isolation joints have one very simple purpose—they completely isolate the slab from something else. That something

else can be a wall or a column or a drain pipe. Here are a few things to consider with isolation joints:

Walls and columns, which are on their own footings that are deeper than the slab subgrade, are not going to

move the same way a slab does as it shrinks or expands from drying or temperature changes or as the subgrade

compresses a little.

Even wooden columns should be isolated from the slab.

If slabs are connected to walls or columns or pipes, as they contract or settle there will be restraint, which

usually cracks the slab—although it could also damage pipes (standpipes or floor drains).

Expansion joints are virtually never needed with interior slabs, because the concrete doesn’t expand that much—

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it never gets that hot.

Expansion joints in concrete pavement are also seldom needed, since the contraction joints open enough (from

drying shrinkage) to account for temperature expansion. The exception might be where a pavement or parking

lot are next to a bridge or building—then we simply use a slightly wider isolation joint (maybe ¾ inch instead of

½ inch).

Blowups, from expansion of concrete due to hot weather and sun, are more commonly caused by contraction

joints that are not sealed and that then fill up with non-compressible materials (rocks, dirt). They can also be due

to very long unjointed sections.

Very long unjointed sections can expand enough from the hot sun to cause blowups, but this is rare.

Isolation joints are formed by placing preformed joint material next to the column or wall or standpipe prior to

pouring the slab. Isolation joint material is typically asphalt-impregnated fiberboard, although plastic, cork,

rubber, and neoprene are also available.

Isolation joint material should go all the way through the slab, starting at the subbase, but should not extend

above the top.

For a cleaner looking isolation joint, the top part of the preformed filler can be cut off and the space filled with

elastomeric sealant. Some proprietary joints come with removable caps to form this sealant reservoir.

Joint materials range from inexpensive asphalt-impregnated fiberboard to cork to closed cell neoprene. Cork can

expand and contract with the joint, does not extrude, and seals out water. Scott Whitelam with APS Cork says

that the required performance is what determines the choice of joint materials. How much motion is expect,

exposure to salts or chemicals, and the value of the structure would all come into play—and of course the cost.

Polyethylene foam isolation joint material comes in various colors. C2 Products

At columns, contraction joints should approach from all four directions ending at the isolation joint, which should

have a circular or a diamond shaped configuration around the column. For an I-beam type steel column, a

pinwheel configuration can work. Always place the slab concrete first and do not install the isolation joint material

and fill around the column until the column is carrying its full dead

JOINTS IN LIQUID RETAINING CONCRETE STRUCTURES

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JOINTS IN LIQUID RETAINING CONCRETESTRUCTURES

1. MOVEMENT JOINTS:

There are three types of movement joints.

(i) Contraction Joint: It is a movement joint with

deliberate discontinuity without initial gap between

the concrete on either side of the joint . The purpose

of this joint is to accommodate contraction of the

concrete. The joint is shown in Fig. 1 (a).

Contraction Joint in Water Tanks

Fig. 1(a)

A contraction joint may be either complete contraction joint or partial contraction joint. A complete

contraction joint is one in which both steel and concrete are interrupted and a partial contraction

joint is one in which only the concrete is interrupted, the reinforcing steel running through as shown

in Fig. 1(b) .

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Fig. 1

(ii) Expansion Joint: It is a joint with complete discontinuity in both reinforcing steel and concrete

and it is to accommodate either expansion or contraction of the structure. A typical expansion joint is

shown in Fig.2.

Fig. 2.

This type of joint requires the provision of an initial gap between the adjoining parts of a structure

which by closing or opening accommodates the expansion or contraction of the structure.

(iii) Sliding Joint: It is a joint with complete discontinuity in both reinforcement and concrete and

with special provision to facilitate movement in plane of the joint . A typical joint is shown in Fig. 3.

Fig. 3.

This type of joint is provided between wall and floor in some cylindrical tank designs.

2. CONTRACTION JOINTS

This type of joint is provided for convenience in construct ion. Arrangement is made to achieve

subsequent continuity without relative movement. One application of these joints is between

successive lifts in a reservoir wall. A typical joint is shown in Fig. 4.

The number of joints should be as small as possible and these joints should be kept from possibility

of percolation of water.

3. TEMPORARY JOINTS

A gap is sometimes left temporarily between the concrete of adjoining parts of a structure which

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after a suitable interval and before the structure is put to use, is filled with mortar or concrete

completely as in Fig.5(a) or as shown in Fig.5 (b) and (c) with suitable jointing materials. In the first

case width of the gap should be sufficient to al low the sides to be prepared before filling.

Fig: 5 (a)

Fig. 5(b)

Fig. 5(c)

SPACING OF JOINTS IN LIQUID RETAINING CONCRETE STRUCTURES:

Unless alternative effective means are taken to avoid cracks by al lowing for the additional stresses

that may be induced by temperature or shrinkage changes or by unequal settlement, movement

joints should be provided at the following spacing:-

(a) In reinforced concrete floors, movement joints should be spaced at not more than 7.5m apart in

two direct ions at right angles. The wall and floor joints should be in line except where sliding joints

occur at the base of the wall in which correspondence is not so important .

(b)For floors with only nominal percentage of reinforcement (smaller than the minimum specified)

the concrete floor should be cast in panels with sides not more than 4.5m.

(c) In concrete walls, the movement joints should normally be placed at a maximum spacing of

7.5m. In reinforced walls and 6m in unreinforced walls. The maximum length desirable between

vertical movement joints will depend upon the tensile strength of the walls, and may be increased by

sui table reinforcement . When a sliding layer is placed at the foundation of a wall , the length of the

wall that can be kept free of cracks depends on the capacity of wall sect ion to resist the friction

induced at the plane of sliding.

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TAGS Contraction Joints Expansion joints Joints in Concrete Liquid Retaining Structure Water Tank Design

Water Tanks

Approximately the wall has to stand the effect of a force at the place of sliding equal to weight of half

the length of wall multiplied by the co-efficient of friction.

(d)Amongst the movement joints in floors and walls as mentioned above expansion joints should

normally be provided at a spacing of not more than 30m between successive expansion joints or

between the end of the structure and the next expansion joint ; al l other joints being of the

construct ion type.

(e) When, however, the temperature changes to be accommodated are abnormal or occur more

frequently than usual as in the case of storage of warm liquids or in uninsulated roof slabs, a smaller

spacing than 30m should be adopted that is greater proportion of movement joints should be of the

expansion type). When the range of temperature is small, for example, in certain covered structures,

or where restraint is small , for example, in certain elevated structures none of the movement joints

provided in small structures up to 45mlength need be of the expansion type. Where sliding joints are

provided between the walls and either the floor or roof, the provision of movement joints in each

element can be considered independently.

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LEED CERTIFICATION & BENEFITS

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Home Building Technology

LEED CERTIFICATION & BENEFITS

What is LEED certification?

In the United States and in a number of other

countries around the world, LEED certification is the

recognized standard for measuring building

sustainability. Achieving LEED certification is the best

way for you to demonstrate that your building project

is truly “green.”

The LEED green building rating system — developed

and administered by the U.S. Green Building Council,

a Washington D.C.-based, nonprofit coalition of

building industry leaders — is designed to promote

design and construction practices that increase profitability while reducing the negative

environmental impacts of buildings and improving occupant health and well-being.

LEED Logo

What are the benefits of LEED certification?

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LEED certification, which includes a rigorous third-party commissioning process, offers compelling

proof to you, your clients, your peers and the public at large that you’ve achieved your

environmental goals and your building is performing as designed. Getting certified allows you take

advantage of a growing number of state and local government incentives, and can help boost press

interest in your project.

The LEED rating system offers four certification levels for new construction — Certified, Silver, Gold

and Platinum — that correspond to the number of credits accrued in five green design categories:

sustainable sites, water efficiency, energy and atmosphere, materials and resources and indoor

environmental quality. LEED standards cover new commercial construction and major renovation

projects, interiors projects and existing building operations. Standards are under development to

cover commercial “core & shell” construction, new home construction and neighborhood

developments.

How does one achieve LEED certification?

The U.S. Green Building Council’s LEED website provides tools for building professionals, including:

Information on the LEED certification process.

LEED documents, such as checklists and reference guides. Standards are now available or in

development for the following project types:

New commercial construction and major renovation projects (LEED-NC)

Existing building operations (LEED-EB)

Commercial interiors projects (LEED-CI)

Core and shell projects (LEED-CS)

Homes (LEED-H)

Neighborhood Development (LEED-ND)

A list of LEED-certified projects

A directory of LEED-accredited professionals

Information on LEED training workshops

A calendar of green building industry conferences

Tips for Getting LEED Certified

Set a clear environmental target. Before you begin the design phase of your project, decide

what level of LEED certification you are aiming for and settle on a firm overall budget. Also

consider including an optional higher certification target — a “stretch” goal — to stimulate

creativity.

LEED CERTIFICATION & BENEFITS

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Set a clear and adequate budget. Higher levels of LEED certification, such as Platinum, do

require additional expenditure and should be budgeted for accordingly

Stick to your budget and your LEED goal. Throughout out the design and building process, be

sure your entire project team is focused on meeting your LEED goal on budget. Maintain the

environmental and economic integrity of your project at every turn.

Engineer for Life Cycle Value As you value-engineer your project, be sure to examine green

investments in terms of how they will affect expenses over the entire life of the building. Before

you decide to cut a line item, look first at its relationship to other features to see if keeping it will

help you achieve money-saving synergies, as well as LEED credits. Many energy-saving features

allow for the resizing or elimination of other equipment, or reduce total capital costs by paying for

themselves immediately or within a few months of operation. Prior to beginning, set your goals for

“life cycle” value-engineering rather than “first cost” value-engineering.

Hire LEED-accredited professionals. Thousands of architects, consultants, engineers, product

marketers, environmentalists and other building industry professionals around the country have a

demonstrated knowledge of green building and the LEED rating system and process — and can

assist you in meeting your LEED goal. These professionals can suggest ways to earn LEED credits

without extra cost, identify means of offsetting certain expenses with savings in other areas and

spot opportunities for synergies in your project.

Fig: 1225 Connecticut Avenue in Washington, D.C., is the first redeveloped office building on the

East Coast to receive LEED Platinum status.

MANUFACTURED SAND (M-SAND) IN CONSTRUCTION

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MANUFACTURED SAND (M-SAND) INCONSTRUCTION

Manufactured sand is a substitute of river for

construction purposes sand produced from hard

granite stone by crushing. The crushed sand is of

cubical shape with grounded edges, washed and

graded to as a construction material. The size of

manufactured sand (M-Sand) is less than 4.75mm.

Why Manufactured Sand is Used?

Manufactured sand is an alternative for river sand.

Due to fast growing construction industry, the

demand for sand has increased tremendously,

causing deficiency of suitable river sand in most part

of the word. Due to the depletion of good quality river sand for the use of construction, the use of

manufactured sand has been increased. Another reason for use of M-Sand is its availability and

transportation cost. Since this sand can be crushed from hard granite rocks, it can be readily

available at the nearby place, reducing the cost of transportation from far-off river sand bed.

Thus, the cost of construction can be controlled by the use of manufactured sand as an alternative

material for construction. The other advantage of using M-Sand is, it can be dust free, the sizes of

m-sand can be controlled easily so that it meets the required grading for the given construction.

Sand

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TAGS Building Materials Sand

Advantages of Manufactured Sand (M-Sand) are:

It is well graded in the required proportion.

It does not contain organic and soluble compound that affects the setting time and properties of

cement, thus the required strength of concrete can be maintained.

It does not have the presence of impurities such as clay, dust and silt coatings, increase water

requirement as in the case of river sand which impair bond between cement paste and aggregate.

Thus, increased quality and durability of concrete.

M-Sand is obtained from specific hard rock (granite) using the state-of-the-art International

technology, thus the required property of sand is obtained.

M-Sand is cubical in shape and is manufactured using technology like High Carbon steel hit rock

and then ROCK ON ROCK process which is synonymous to that of natural process undergoing in

river sand information.

Modern and imported machines are used to produce M-Sand to ensure required grading zone for

the sand.

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MATERIALS FOR DAMP PROOF COURSE

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Home Building Technology Building Materials

MATERIALS FOR DAMP PROOF COURSE

Damp proof course (DPC) is a barrier of impervious

material built into a wall or pier to prevent moisture

from moving to any part of the building.

Following are the materials generally used for

damp proofing of structures:

1) Flexible Materials:

The materials, which do not crack and deform their

shape when subjected to loading, are called Flexible

Materials

a) Bitumen Mastic (Mastic Asphalt)

It consists of asphalt or bitumen mixed with fine sand in hot state to form an impervious mass.

Due to this consistency it can be spread (when hot) to a depth of 2.5cm to 5cm, which sets on

cooling.

It provides good impervious layer but special care is needed in its laying.

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b) Bitumen Felts (Sheets):

It consists of 6mm thick sheet of bitumen prepared in rolls having width equal to that of brick

wall.

c) Hot laid Bitumen:

This material is used on a bedding of cement concrete or mortar.

This should be applied in two layers at the rate of 1.75kg/m of the area.

d) Metal Sheets:

Metal sheets of Copper, Aluminium, or Lead are used to prevent dampness, but they are costly.

Sheets of these materials are used throughout the thickness of the wall.

The sheets of Lead are laid over Lime Mortar and not with Cement.

Mortar due to the chemical reaction of Cement over the Lead.

The sheets of metal should be coated with asphalt.

The thickness of the sheets should not be less than 3mm.

damp-proof-course

2) Rigid Materials:

The materials, which do not resist transverse stresses and cracks when subjected to sever

loading, are known as Rigid Materials.

a) Rich Concrete

1.2cm to 4cm thick layer of Rich Concrete (1:2:4) painted with two coats of hot bitumen is used

as horizontal D.P.C.

It also prevents the moisture penetration by capillary action.

These layers are laid where the damp is not excessive.

b) Mortar:

2cm thick layer of Rich Cement and Sand Mortar (1:3) is applied on the inner face of external

2

MATERIALS FOR DAMP PROOF COURSE

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TAGS Building Materials DPC

wall.

This is a vertical D.P.C.

The surface is than painted with two coats of hot bitumen.

c) Bricks:

Over burnt or dense bricks in one or two layers can be used as cheap and effective DPC.

They are laid in Rich Cement and Sand Mortar (1:3).

Bricks are rarely used as DPC except in cheap houses.

d) Stones or Slates:

Two layers of stone slabs or slates laid in Lime, Cement and Sand Mortar (1:1:6) make a best

DPC.

They can also be laid in Cement Sand Mortar.

It is used where a good quality of stone is easily and cheaply available.

Read More on Damp Proof Course

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MULTI-STOREY CAR PARKING SYSTEM - PROJECT REPORT

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MULTI-STOREY CAR PARKING SYSTEM –PROJECT REPORT

Automatic multistoried car parking system helps to

minimize the parking area. In the modern world

where parking space has become a very big problem,

it has become very important to avoid the wastage of

space in modern big companies and apartments etc.

in places where more than 100 cars need to be

parked, this system proves to be useful in reducing

wastage of space. This automatic car parking system

enables the parking of vehicles, floor after floor and

thus reducing the space used. Here any number of

cars can be parked according to the requirement.

These makes the system modernized and thus space-

saving one. This idea is developed using 8051

microcontroller.

THEORY OF PROJECT

A display is provided at the ground floor which is basically a counter which will count the number of

cars in each floor and according to that message will be displayed on it. A gate is also provided at

the ground floor which is controlled by the stepper motor. Before the gate an IR pair is provided to

sense that the car has reached towards the gate. For e.g. suppose a car reaches between the 2 IR

pairs, then the LCD will display the particular floor on which car can be parked. As soon as the car

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crosses the 2 IR pair, the gate will open automatically. An indicator with green and red led is kept

on each floor to indicate whether the car can be parked on that particular floor or not. If green led of

any particular floor glows, then it will indicate that the particular floor is empty and you can park

your car on that floor. But in case if red led of that particular floor glows, then it will indicate that

there is no vacancy on that floor, in such case you can park your car on the next floor according to

the indication.

If there is no parking place, then all the red indicators of the floors will glow and the LCD will display

“NO SPACE FOR PARKING” and the gate will remain closed.

Program is written using 8051 microcontroller. All the circuits are interfaced with it.

ADVANTAGES OF MULTI-STORY CAR PARKING:-

Any like Newyork, Delhi, London has over five million cars and two-wheelers on its roads, but not

enough parking spaces. The demand for parking space has, on an average in the main markets of

Delhi, outstripped demand by 43 per cent. It is not just a problem of Delhi or Mumbai; all the big

cities in India are facing the space crunch. Parking space is fast becoming a major issue in other

cities like Kolkata, Bangalore, Hyderabad, Ahmedabad, Chandigarh, Pune and other urban and semi-

urban cities.

Multi-storey car parks provide lower building cost per parking slot, as they typically require less

building volume and less ground area than a conventional facility with the same capacity.

A multi-storey car parks offer greatest possible flexibility for the realization of optimum parking

solution. Time-saving vertical and horizontal movements take place simultaneously ensuring fast

parking and retrieval times.

DISADVANTAGES OF MULTI-STORY CAR PARKING:-

Drivers who use multi-story parking facilities, sometimes known as parking garages, often enjoy a

number of benefits the structures provide. Despite the ability of the garages to house a large

number of cars, multi-story parking facilities also carry a number of distinct disadvantages that arise

from their tall, enclosed and often dimly lit nature.

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1.Deterioration and Maintenance

Multi-story parking facilities support hundreds of thousands of pounds of vehicles, people and

equipment every day. Because the garages support very large amounts of weight and loads that

constantly change, the structures quickly deteriorate in the absence of constant maintenance

activity. In addition, according to Canada’s National Resource Council, changing weather and

environmental conditions can deteriorate a garage’s steel support structure, creating an unsafe

environment for garage users. A number of corrosion inhibitors can help delay processes that eat

away at the structure’s integrity, according to the National Resource Council, but constant

maintenance and upkeep must include anti-corrosion measures to keep multi-story parking facilities

structurally sound.

2.Parking Angle Considerations

Because many drivers of varying levels of skills and experience drive in, around and out of parking

garages every day, designers must pay special attention to the configuration of parking spaces

within the structures. In a municipal parking garage presentation prepared by architects Sakri and

Khairuddin, the designers noted that two-way traffic flow in a multi-story garage presents a number

of parking challenges for drivers and designers. Parallel parking, for example, creates an inefficient

use of limited space, while straight parking spaces make parking difficult for some drivers. Other

options, like angled parking, do not work well with a two-way traffic flow and can only work well in

garages with separate entrance and exit openings.

3.Lighting

While most parking lots open at night, multi-story or otherwise, require some form of lighting, the

multi-story nature of parking garages creates a need for numerous lights throughout the structure.

In addition, because the inside of the structure may remain dark even during the day, many of these

lights must run at all times. This arrangement can create high energy bills for garage owners and

may require frequent lighting maintenance to replace broken or burned-out bulbs.

4.Safety

Because multi-story parking facilities allow limited natural light inside, some security experts express

concern about safety inside the structures. In their municipal presentation, architects Sakri and

Khairuddin recommend security devices that directly connect to local police or public safety stations.

In addition, the architects explicitly describe a need to reduce dark places where criminals may hide.

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BAMBOO REINFORCED CONCRETE

Even with security measures in place, though, criminals still seem to thrive in multi-story parking

structures; in a 2009 article in the Chicago Sun-Times, one parking garage user expressed

frustration after experiencing three burglaries within two years.

This project Report was submitted by Sai Krishna.

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NDT TESTING EQUIPMENTS FOR CONCRETE STRENGTH

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NDT TESTING EQUIPMENTS FOR CONCRETESTRENGTH

Non-Destructive Tests are useful for testing and

evaluation of concrete strength after construction

and during its lifetime. NDT tests are conducted to

ensure the quality of concrete construction as per

required specification for intended use. Various Non

Destructive Testing Equipments for concrete strength

evaluation are available. These NDT Testing

equipments are useful to assess concrete

construction quality.

Following are various NDT Test equipments for

concrete strength evaluation:

1. Rebound Hammer:

Rebound hammer is used for testing surface strength of concrete. Rebound hammer provides

rebound number after testing of concrete which is used for concrete strength estimation.

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NDT TESTING EQUIPMENTS FOR CONCRETE STRENGTH

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Operation of the rebound hammer

2. Ultrasonic Pulse Velocity Meter:

Ultrasonic pulse velocity meter is used for quality of concrete after construction. Qualities such as

uniformity and homogeneity of concrete, location of internal defects in concrete, porosity, cracks.

3. Concrete Pull off Tester:

Concrete pull off testing equipment is used for testing of bond strength of concrete. This test is used

for assessment of surface zone strength of concrete.

4. Pull out Testing Equipment:

There are two types of pull out tests. One is Pull out “LOK” test which is used for testing concrete

during construction stage while other test Pull Out “Capo” Test is used for testing concrete after

construction. Both of these tests are used for assessment of concrete surface zone strength and

measures the pull out force for concrete.

5. Break off Tester:

Break off test is used for assessment of compressive strength or flexure strength of concrete. This

test is continued till the concrete fails.

6. Windsor Probe Test:

Windsor probe test is also used for assessment of surface zone strength of concrete. This test is done

to assess the penetration resistance of concrete.

7. Micro Core Test Apparatus:

This equipment is used for testing the core (micro core) strength of concrete. This is a in-situ test for

concrete structures.

NDT TESTING EQUIPMENTS FOR CONCRETE STRENGTH

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8. Bond Tester:

Bond tester equipment is used for testing the bond strength between two concrete layer. Bond

strength between two layers also indicates the tensile strength of concrete between two layers.

9. Maturity Meters:

Maturity meters are used for estimation of compressive strength of concrete after placement of

concrete and initial setting. This test predicts the concrete strength based on the temperature of

history of concrete. This tests is a measure of progress of hydration reaction of concrete. This test

can be useful for strength estimation if structure has to be occupied before final setting of concrete,

or the construction of structure above has to be started.

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PERFORMANCE OF VARIOUS TYPES OF BUILDINGS DURING EARTHQUAKE

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PERFORMANCE OF VARIOUS TYPES OFBUILDINGS DURING EARTHQUAKE

Different types of buildings suffer different degrees of

damage during earthquakes and the same has been

studied here.

1. MUD AND ADOBE HOUSES:

Unburnt sun dried bricks laid in mud mortar are

called adobe construction. Mud houses are the

traditional construction, for poor and most suitable in

view of their initial cost, easy availability, low level

skill for construction and excellent insulation against

heat and cold. More than 100 million people in India

live in these type of houses. There are numerous

examples of complete collapse of such buildings in 1906 Assam, 1948 Ashkhabad, 1960 Agadir, 1966

Tashkent, 1967 Koyna, 1975 Kinnaur, 1979 Indo-Nepal, 1980 Jammu and Kashmir and 1982 Dhamar

earthquakes. It is very weak in shear, tension and compression. Separation of walls at corner and

junctions takes place easily under ground shaking. The cracks pass through the poor joints. After the

walls fail either due to bending or shearing in combination with the compressive loads, the whole

house crashes down. Extensive damage was observed during earthquake especially if it occurs after

a rainfall, (Krishna and Chandra, 1983).

Better performance is obtained by mixing the mud with clay to provide the cohesive strength. The

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PERFORMANCE OF VARIOUS TYPES OF BUILDINGS DURING EARTHQUAKE

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mixing of straw improves the tensile strength. Coating the outer wall with waterproof substance such

as bitumen improves against weathering. The strength of mud walls can be improved significantly by

spilt bamboo or timber reinforcement. Timber frame or horizontal timber runners at lintel level with

vertical members at corners further improves its resistance to lateral forces which has been observed

during the earthquakes.

2. MASONRY BUILDINGS:

Masonry buildings of brick and stone are superior with respect to durability, fire resistance, heat

resistance and formative effects. Masonry buildings consist of various material and sizes (i) Large

block (block size >50 cm)-concrete blocks, rock blocks or lime stones;(ii) concrete brick-solid and

hollow; (iii) Natural stone masonry. Because of its easy availability, economic reasons and the merits

mentioned above this type of construction are widely used. In very remote areas in Himalayas

buildings are constructed of stacks of random rock pieces without any mortar. The majority of new

construction use mud mortar, however, few use cement mortar also.

Causes of failure of masonry buildings:

These buildings are very heavy and attract large inertia forces. Unreinforced masonry walls are weak

against tension (Horizontal forces) and shear, and therefore, perform rather poor during

earthquakes. These buildings have large in plane rigidity and therefore have low time periods of

vibration, which results in large seismic force. These buildings fall apart and collapsed because of

lack of integrity. The lack of structural integrity could be due to lack of ‘through’ stones, absence of

bonding between cross walls, absence of diaphragm action of roofs and lack of box light action.

Common type of damage in masonry building:

All of them undergo severe damage resulting in complete collapse and pileup ina heap of stones. The

inertia forces due to roof or floor is transmitted to the top of the walls and if the roofing material is

improperly tied to the wall, it will be dislodged. The weak roof support connection is the cause of

separation of roof from the support and leads to complete collapse. The failure of bottom chord of

roof truss may also cause complete collapse of truss as well as the whole building.

PERFORMANCE OF VARIOUS TYPES OF BUILDINGS DURING EARTHQUAKE

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If the roof/floor material is properly tied to the top walls causing it to shear of diagonally in the

direction motion through the bedding joints. The cracks usually initiate at the corners of the

openings. The failure of pier occurs due to combined action of flexure and shear. Near vertical cracks

near corner wall joint occur indicating separations of walls.

For motion perpendicular to the walls, the bending moment at the ends result in cracking and

separation of the walls due to poor bonding. Generally gable end wall collapses. Due to large inertia

forces acting on the walls, the Wythe of masonry is either bulge outward or inward. The falling away

of half the wall thickness on the bulged side is common feature. The bonding stone is found to be

effective as in Jammu Kashmir earthquake of August 24, 1980. Unreinforced dressed rubble

masonry (DRM) has shown slightly better performance than random rubble masonry. The most

common damage is due to cracks in the walls. The masonry with lower unit mass and greater bond

strength shows better performance. The unreinforced masonry as a rule should be avoided as a

construction material as far as possible in seismic area.

3. REINFORCED MASONRY BUILDINGS:

Reinforced masonry buildings have withstood earthquakes well, without appreciable damage. For

horizontal bending, a tough member capable of taking bending if found to perform better during

earthquakes. If the corner sections or opening are reinforced with steel bars even greater strength is

attained. Even dry packed stone masonry wall with continuous lintel band over openings and cross

walls did not undergo any damage.

4. BRICK-R.C. FRAME BUILDINGS:

This type of building consists of RC frame structures and brick lay in cement mortar as infill. This

type of construction is suitable in seismic areas.

Causes of failure of RC frame buildings:

The failures are due to mainly lack of good design of beams /columns frame action and foundation.

Poor quality of construction inadequate detailing or laying of reinforcement in various components

particularly at joints and in columns /beams for ductility. Inadequate diaphragm action of roof and

floors. Inadequate treatment of masonry walls.

Common type of damage in RC frame buildings:

PERFORMANCE OF VARIOUS TYPES OF BUILDINGS DURING EARTHQUAKE

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The damage is mostly due to failure of infill, or failure of columns or beams. Spalling of concrete in

columns. Cracking or buckling due to excessive bending combined with dead load may damage the

column. The buckling of columns are significant when the columns are slender and the spacing of

stirrup in the column is large.

Severe crack occurs near rigid joints of frame due to shearing action, which may lead to complete

collapse. The differential settlement also causes excessive moments in the frame and may lead to

failure. Design of frame should be such that the plastic hinge is confined to beam only, because

beam failure is less damaging than the common failure.

5. WOODEN BUILDINGS:

This is also most common type of construction in areas of high seismicity. It is also most suitable

material for earthquake resistant construction due to its light weight and shear strength across the

grains as observed in 1933 Long beach, 1952 Kern country, 1963 Skopje, and 1964 Anchorage

earthquake. However during off- Tokachi earthquake (1968), more than 4,000 wooden buildings

were either totally pr partially damaged. In addition there were failure due to sliding and caving in

due to softness of ground. The main reason of failure was its low rigidity joints, which acts as a

hinge. Failure is also due to deterioration of wood with passage of time. Wood frames without walls

have almost no resistants against horizontal forces. Resistant is highest for diagonal braced wall.

Buildings with diagonal bracing in both vertical and horizontal plane perform much better. The

traditional wood frame Ikra construction of Assam and houses of Nicobars founded on wooden piles

separated from ground have performed very well during earthquakes. Wood houses are generally

suitable up to two storeys.

6. REINFORCED CONCRETE BUILDINGS:

This type of construction consists of shear walls and frames of concrete. Substantial damage to

reinforced concrete buildings was seen in the Kanto (1923) earthquake. Later in Niigata (1964), Off-

Tokachi (1968) and Venezuela (1967) earthquake it suffered heavy damages. The damage to

reinforced concrete buildings may be divided broadly into vibratory failure and tilting or uneven

settlement. When a reinforced concrete building is constructed on comparatively hard ground

vibratory failure is seen, while on soft ground tilting, uneven settlement or sinking is observed.

In case of vibratory failure the causes of damage may be considered to be different for each case,

but basically, the seismic forces, which acted on a building during the earthquake, exceeded the

loads considered in the design, and the buildings did not have adequate resistance and ductility to

PERFORMANCE OF VARIOUS TYPES OF BUILDINGS DURING EARTHQUAKE

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withstand them. In general these buildings performed well as observed in Skopje (1963) and Kern

country (1952) earthquakes.

The shear walls are fond to be effective to provide adequate strength to the buildings. Severe

damage to spandrel wall between the vertical openings is observed.

Tilting and singing of reinforced concrete buildings during earthquakes were seen in the Kanto and

Niigata earthquakes. Most failed because the dead weights could not be supported after the settling

of the ground. Such damage is peculiar to buildings in soft ground, the damage becomes higher in

the following order: pile foundation, mat foundation, continuous foundation and independent

foundation.

The hollow concrete block buildings with steel reinforcement in selected grout filled cells have shown

good performance. The Precast and prestressed reinforced concrete buildings also suffered severe

damage mostly because of poor behaviour of joints or supports. The Precast and prestressed

element as a rule were not destroyed as observed in 1952 Kern country and 1964 Anchorage

earthquakes.

building earthquake performance

7. STEEL SKELETON BUILDINGS:

Buildings with steel skeleton construction differ greatly according to shapes of cross sections and

method of connection. They may be broadly divided into two varieties, those employing braces as

earthquake resistant elements and those which are rigid frame structures. The former is used in low

building while the later is used in high-rise buildings.

When braces are used as earthquake resistant elements, it is normal to design so that all horizontal

forces will be borne by the braces. This type of building is generally light and influence of wind loads

is dominant in most cases. However, there are many cases in which the braces have shown breaking

or buckling in which joints have failed (Wiegel, 1970).

Steel skeleton construction, particularly the structural type in which frames are comprised of beams

and columns consisting of single member H-beams, is often used in high-rise buildings. The non-

structural damage is common but none of these building severely damages as observed in 1906 San

Francisco earthquake

PERFORMANCE OF VARIOUS TYPES OF BUILDINGS DURING EARTHQUAKE

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APPLICATION OF FERRO-CEMENT INCONSTRUCTION

8. STEEL AND REINFORCED CONCRETE COMPOSITE STRUCTURES:

Steel and Reinforced Concrete Composite Structures are composed of steel skeleton and reinforced

concrete and have the dynamic characteristics of both. It is better with respect to fire resistance and

safety against buckling as compared to steel skeleton. Whereas compared to reinforced concrete

structures it has better ductility after yielding. As these features are the properties, which are

effective for making a building earthquake resistant and are, found to perform better during

earthquakes (Wiegel, 1970).

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PLANNING OF CONSTRUCTION PROJECT

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PLANNING OF CONSTRUCTION PROJECT

Planning is the first step of project management

philosophy of planning, organizing and controlling the

execution of the projects. Project planning and

project scheduling is two separate and distinct

function of the project management. Here, we will

learn about the planning phase of project

management.

Project planning is the function in which project and

construction managers and their key staff members

prepares the master plan. Then this master plan is

put into time schedule by scheduling people which is

called project scheduling. A project plan is mostly

responsible for the success or failure of the project.

construction-project-planning

Definition of Planning:

Planning is a bridge between the experiences of the past projects and the proposed actions that

produces favourable results in the future. It can also be said that it is a precaution by which we can

reduce undesirable effects or unexpected happenings and thereby eliminating confusion, waste, and

loss of efficiency. Planning involves prior determination, specification of factors, forces, effects and

relationships necessary to reach the desired goals.

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PLANNING OF CONSTRUCTION PROJECT

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Planning Philosophy:

Planning should be done logically, thoroughly and honestly to have a chance to succeed. The

previous experiences of projects provides basic planning logic. Then difference between previous

projects and current projects shall be known to make any exceptional features in the basic planning

logic. These differences can be unusual client requirement, out of the way location, potential external

or internal delaying factors etc. these potential problems shall have to be tackled in order to reduce

their negative effect preparing master plan of the project and later scheduling of the project. Provide

each aspect of the plan an individual scrutiny with input from past experiences and from experts.

Types of Planning:

There are several types of project planning. The three major types of construction project planning

are:

1. Strategic planning: this involves the high-level selection of the project objectives

2. Operational planning: this involves the detailed planning required to meet the strategic

objectives

3. Scheduling: this puts the detailed operational plan on a time scale set by the strategic

objectives.

Strategic planning is done by the owner’s corporate planners. In this they decide what project to

build and what the completion date has to be to meet the owner’s project goals. The construction

teams formulates the master construction execution plan within the guidelines set in the strategic

and contracting plans.

Operational Planning:

Operational planning is done by construction teams. They ask certain questions before making

operational plan for the project. They are:

PLANNING OF CONSTRUCTION PROJECT

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Will the operational plan meet the strategic planning target date?

Are sufficient construction resources and services available within the company to meet the

project objectives?

What is the impact of the new project on the existing work load?

Where will we get the resources to handle any overload?

What company policies may prevent the plan from meeting the target date?

Are usually long delivery equipment or materials involved?

Are the project concepts and design firmly established and redy to start the construction?

Is the original contracting plan still valid?

Will it be more economical to use a fast-track scheduling approach?

All these questions are answered in preparation of the construction master plan before detailed

scheduling of the project.

What is Construction Master Plan?

A construction master plan addresses how will the project be planned, organized, and major work

activities be controlled to meet the goals of finishing the work on time, within budget and as

specified.

Contracting plan is the major consideration in formulating the master construction plan, which

answers a lot of questions. Questions related to government and social restraint, resources for

construction, owner’s policies or legal requirements, contractual requirement affecting master plan

are not answered by contracting plan. Answers to these questions must be found during the

development of the project execution plan.

Project execution plan shall be reviewed and evaluation shall be done as the work progresses. Minor

variations are common but major changes shall be considered with extreme caution.

The construction project master plan shall be completed and approved and after that time plan

(scheduling), budget plan, resource plan shall be carried out.

PLANNING, SCHEDULING AND CONSTRUCTION MANAGEMENT

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PLANNING, SCHEDULING AND CONSTRUCTIONMANAGEMENT

Planning, scheduling is an important part of the

construction project management. Planning and

scheduling of construction activities helps engineers

to complete the project in time and within the

budget.

The term ‘Construction’ does not only denotes

physical activities involving men, materials and

machinery but also covers the entire gamut of

activities from conception to realization of a

construction project. Thus, management of resources

such as men, materials, machinery requires effective

planning and scheduling of each activity.

Construction Management :

Management is the science and art of planning, organizing, leading and controlling the work of

organization members and of using all available organization resources to reach stated organizational

goals.

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PLANNING, SCHEDULING AND CONSTRUCTION MANAGEMENT

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Construction management deals with economical consumption of the resources available in the least

possible time for successful completion of construction project. ‘Men’, ‘materials’, ‘machinery’ and

‘money’ are termed as resources in construction Management.

Objectives of Construction Management :

The main objectives of construction management are,

Completing the work with in estimated budget and specified time.

Maintaining a reputation for high quality workmanship

Taking sound decisions and delegation of authority

Developing an organization that works as a team.

Functions of Construction Management

The functions of construction Management are

(a) Planning

(b) Scheduling

(c) Organizing

(d) Staffing

(e) Directing

(f) Controlling

(g) Coordinating

(a) Construction Project Planning:

It is the process of selecting a particular method and the order of work to be adopted for a project

from all the possible ways and sequences in which it could be done. It essentially covers the aspects

PLANNING, SCHEDULING AND CONSTRUCTION MANAGEMENT

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of ‘What to do’ and ‘How to do it’.

Construction Project Planning

Importance of construction project planning :

Planning helps to minimize the cost by optimum utilization of available resources.

Planning reduces irrational approaches, duplication of works and inter departmental conflicts.

Planning encourages innovation and creativity among the construction managers.

Planning imparts competitive strength to the enterprise.

b) Construction Project Scheduling:

Scheduling is the fitting of the final work plan to a time ? scale. It shows the duration and order of

various construction activities. It deals with the aspect of ‘when to do it’.

Importance of scheduling:

Scheduling of the programming, planning and construction process is a vital tool in both the daily

management and reporting of the project progress.

c) Organizing:

Organizing is concerned with decision of the total construction work into manageable

departments/sections and systematically managing various operations by delegating specific tasks to

individuals.

d) Staffing:

Staffing is the provision of right people to each section / department created for successful

completion of a construction project.

e) Directing:

It is concerned with training sub ordinates to carryout assigned tasks, supervising their work and

guiding their efforts. It also involves motivating staff to achieve desired results.

PLANNING, SCHEDULING AND CONSTRUCTION MANAGEMENT

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f) Controlling:

It involves a constant review of the work plan to check on actual achievements and to discover and

rectify deviation through appropriate corrective measures.

g) Coordinating:

It involves bringing together and coordinating the work of various departments and sections so as to

have good communication. It is necessary for each section to aware of its role and the assistance to

be expected from others.

Importance of Construction Management :

Proper management practices invariably lead to “maximum production at least cost”. A good

construction management, results in completion of a construction project with in the stipulated

budget.

Construction management provides importance for optimum utilization of resources. In other

words, it results in completion of a construction project with judicious use of available resources.

Construction management provides necessary leadership, motivates employees to complete the

difficult tasks well in time and extracts potential talents of its employees.

Construction management is beneficial to society as the effective and efficient management of

construction projects will avoid, escalation of costs, time overrun, wastage of resources, unlawful

exploitation of labor and pollution of environment.

PLINTH AREA AND PLINTH REGULATION OF THE BUILDING

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Home Building Technology Building Bye Laws

PLINTH AREA AND PLINTH REGULATION OF THEBUILDING

Plinth Area

The minimum area of buildings of different classes

shall be governed by the following:

1. In an industrial plot, the plinth area should not

exceed 60% of the site area.

2. In a market area, the plinth area should not

exceed 75% of the area of site, provided sufficient

off-street parking facilities for loading and

unloading of vehicles are provided on the same

plot as the building.

3. In residential plots, the covered areas should be

as given in the table 1.

Table 1

S. No Area of plot Maximum permissible covered area

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PLINTH AREA AND PLINTH REGULATION OF THE BUILDING

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1 Less than 200 sq.m 66.66 % of the plot area on the ground

and first floor and nothing on the second

floor, except a barsati (garret) not

exceeding 25% of the ground floor.

2 201 to 500 sq.m 50% of the plot area or 133 sq.m

whichever is more.

3 501 to 1000 sq.m 40% of the plot area or 250 sq.m

whichever is more.

4 More than 1000 sq.m 33.33 % of the plot area or 400 sq.m

whichever is more.

Plinth Regulation

a) Main Building: No plinth or any part of a building or outhouse should be less than 30cm above

the determined level of

i. the central part of the abutting street,

ii. the footpath of the abutting street,

iii. the height part of a service lane which determines the drainage of the premises,

iv. any portion of the ground within 3m distance of such a building, and

v. undulating or sloping land 1.2 m above the drainage or country water level.

in cases where adequate drainage of the premises is not assured, the plinth should be of a height

approved by the authority.

b) Interior courtyards: Every courtyard should be raised atleast 15cm above the level of centre of

the nearest street and should be satisfactorily drained. Common courtyards should have independent

access.

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c) Plinth of garages, stables and warehouses: the plinths of such constructions should not be

less than 15cm above the level determined in portion (a) above for main building.

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POOR CONSTRUCTION METHODS AND WORKMANSHIP TO AVOID

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POOR CONSTRUCTION METHODS ANDWORKMANSHIP TO AVOID

Poor construction methods and workmanship is

responsible for the failure of buildings and structure.

The poor construction methods and workmanship is

caused due to negligence and inadequate quality

control at construction site. The effects of some of

the poor construction methods are discussed below:

(a) Incorrect

placement of steel

Incorrect placement of steel can result in insufficient

cover, leading to corrosion of the reinforcement. If

the bars are placed grossly out of position or in the

wrong position, collapse can occur when the element is fully loaded.

(b) Inadequate cover to reinforcement

Inadequate cover to reinforcement permits ingress of moisture, gases and other substances and

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POOR CONSTRUCTION METHODS AND WORKMANSHIP TO AVOID

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leads to corrosion of the reinforcement and cracking and spalling of the concrete.

(c) Incorrectly made construction joints

The main faults in construction joints are lack of preparation and poor compaction. The old concrete

should be washed and a layer of rich concrete laid before pouring is continued. Poor joints allow

ingress of moisture and staining of the concrete face.

(d) Grout leakage

Grout leakage occurs where formwork joints do not fit together properly. The result is a porous area

of concrete that has little or no cement and fine aggregate. All formwork joints should be properly

sealed.

(e) Poor compaction

If concrete is not properly compacted by ramming or vibration the result is a portion of porous

honeycomb concrete. This part must be hacked out and recast. Complete compaction is essential to

give a dense, impermeable concrete.

(f) Segregation

Segregation occurs when the mix ingredients become separated. It is the result of

1. dropping the mix through too great a height in placing (chutes or pipes should be used in such

cases)

2. using a harsh mix with high coarse aggregate content

3. large aggregate sinking due to over-vibration or use of too much plasticizer

Fig: Seggregation of concrete

Segregation results in uneven concrete texture, or porous concrete in some cases.

(g) Poor curing

POOR CONSTRUCTION METHODS AND WORKMANSHIP TO AVOID

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PLASTIC SHRINKAGE CRACKS & ITS PREVENTIONIN CONCRETE

A poor curing procedure can result in loss of water through evaporation. This can cause a reduction

in strength if there is not sufficient water for complete hydration of the cement. Loss of water can

cause shrinkage cracking. During curing the concrete should be kept damp and covered.

(h) Too high a water content

Excess water increases workability but decreases the strength and increases the porosity and

permeability of the hardened concrete,which can lead to corrosion of the reinforcement. The correct

water-to-cement ratio for the mix should be strictly enforced.

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Home Building Technology

Pre – Engineered Metal Buildings – Latest Trends

Pre-Engineered Steel Buildings use a combination of

built-up sections, hot rolled sections and cold formed

elements which provide the basic steel frame work

with a choice of single skin sheeting with added

insulation or insulated sandwich panels for roofing

and wall cladding. The concept is designed to provide

a complete building envelope system which is air

tight, energy efficient, optimum in weight and cost

and, above all, designed to fit user requirement like a

well fitted glove.

These Pre-Engineered Steel Buildings can be fitted

with different structural accessories including

mezzanine floors, canopies, fascias, interior

partitions, crane systems etc. The building is made water-tight by use of special mastic beads, filler

strips and trims. This is a very versatile building system and can be finished internally to serve any

required function and accessorized externally to achieve attractive and distinctive architectural

styles. It is most suitable for any low-rise building and offers numerous benefits over conventional

buildings.

Pre-engineered buildings are generally low rise buildings; however the maximum eave heights can

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go upto 25 to 30 metres. Low rise buildings are ideal for offices, houses, showrooms, shop fronts etc.

The application of pre-engineered concept to low rise buildings is very economical and speedy.

Buildings can be constructed in less than half the normal time especially when complimented with

other engineered sub-systems.

The most common and economical type of low-rise building is a building with ground floor and two

intermediate floors plus roof. The roof of a low rise building may be flat or sloped. Intermediate

floors of low rise buildings are made of mezzanine systems. Single storeyed houses for living take

minimum time for construction and can be built in any type of geographic location like extreme cold

hilly areas, high rain prone areas, plain land, extreme hot climatic zones etc.

There are basically nine major components in a pre-engineered building such as :

Main framing or vertical columns

End wall framing

Purlins, girts and eave struts

Sheeting and insulation or prefab panels

Crane system

Mezzanine system

Bracing system

Paints and finishes

Miscellaneous services

Main Framing

Main framing basically includes the rigid steel frames of the building. The PEB rigid frame comprises

of tapered columns and tapered rafters (the fabricated tapered sections are referred to as built-up

members). The tapered sections are fabricated using the state of art technology wherein the flanges

are welded to the web. Splice plates are welded to the ends of the tapered sections. The frame is

erected by bolting the splice plates of connecting sections together.

For normal housing the main framing columns are of ISMC category.

End wall framingThe endwall frame of a pre-engineered building may be designed as a main rigid frame (i.e. similar

to the interior frame) or as a post and beam frame. The decision depends on the customer’s

requirement (mainly as to whether he wants to go in for future expansion or not ) and / or building’s

requirements (is the endwall open for access).

The post and beam end wall system of framing consists of columns (posts) with pinned ends,

supporting horizontal beams known as endwall rafters. Girts are flush framed between posts to

provide lateral stability and a neat appearance. Post and beam endwalls are assumed to be laterally

stiff due to the diaphragm effect of the wall sheeting. The diaphragm action is proven to be sufficient

enough to resist the transverse wind force acting on the small tributary area of the endwall.

For single storeyed normal houses end wall framing is same as main framing.

Purlins, girts and eave strutsPurlins, girts and eave struts are also known as secondary cold-formed members. There is no

welding involved in their preparation. They are prepared by just bending the steel coil giving it the

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desired shape (Z-shape for purlins and girts, and C-shape for eave struts).

Purlins : Purlins are secondary members supporting the roof panels. Z-shaped purlins are adopted

for pre-engineered buildings that provide a great advantage of being lapped at support points and

nested together to increase the stiffness. This capability provides additional strength and reduces

deflection. On the other hand C-shaped purlins lack this capability and thus are not used as purlins

or girts.

The purlins are subjected to the following loads:–

Gravity loads (dead + live)

Wind uplift (suction) load

Axial force due to longitudinal wind loads (especially for the strut purlins)

Girts : Girts are used to provide framework for wall cladding for sidewalls and endwalls. Generally,

for sidewalls by-framed (by-pass) construction is employed for taking advantage of lapped girts and

flush construction is employed for endwall girts in order to use diaphragm action effectively. All flush

endwall girts are simply supported members attached to the endwall column web.

The girts are subjected to the following loads:–

Gravity load (dead)

Wind pressure and suction

Eave Struts: All eave struts are cold formed C sections. These are simply supported members

(180mm in depth and 2.0mm or 2.5mm in thickness). Eave struts are well suited at the corners to

support sheetings.

The eave struts are subjected to the following loads:–

Gravity loads (dead + live)

Wind uplift (suction) load

Axial loads accumulated through bracings

Panels and insulationSingle skin profile steel sheets are used as roof and wall sheeting, roof and wall liners, partition and

soffit sheeting. The steel sheets are generally made from steel coils and aluminium coils. Minimum

thickness of steel coils used is 0.5mm high tensile steel. The profiles depends upon the stiffness

required, the governing loads (dead/live/wind) etc. The strength of the sheets depends on its profile,

and the depth and number of ribs.

The steel sheets are normally zincalume or galvanized profiled sheets permanently colour coated

either plain or the sheets can be coated with special paints like PVF2 , if required, for better anti-

corrosion properties.

These buildings can be properly insulated by providing fibrous insulation slabs / rolls of non-

combustible Rockwool, Aluminium foil laminated, placed over a metal mesh bed created between the

purlins, and then the roofing steel sheet fixed over it. The siding walls can also be insulated by

providing a double skin profile steel sheet wall cladding having Rockwool Insulation slab sandwiched

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in between and held in position with the help of ‘Z’ spacers in between the two profile steel sheets.

In similar pattern a double skin insulated roofing system can also be erected.

Liner panels are used to conceal the roof purlins, wall girts and the Rockwool insulation on the inside

of the building when neat finished appearance is required. If the temperature inside the building has

to be controlled, insulation of different thickness can be provided below the panels. Another

alternative is to provide pre-fabricated insulated panels, which comprises of two single skin panels

(plain steel sheets zincalume colour coated) with polyurethane foam insulation in between. These

panels are intended for use as thermally efficient roof and wall claddings for buildings e.g. in high

altitude areas and cold storages.

For normal housing the wall panels comprises of outside profiled steel sheet fixed on to the columns

and purlins. Rockwool insulation placed between the purlins and then the inner sheet of a particle /

rigid board type again fixed on to the columns and purlins thereby totally concealing the steel

structure. The roof is of profile steel sheet with insulation fixed underneath. False Ceiling of particle /

rigid board is fixed to a steel frame work hung from the trusses. Insulation can also placed over the

false ceiling packed in polythene. Here a 2 ft. high brick wall is required to be given on the outside

for protection.

For walls a second alternative can be by way of welding metal mesh on to the columns and purlins

on both sides with insulation sandwiched in between and spraying 50mm thick cement plaster on to

the mesh with spray gun.

Crane systemCrane in industrial buildings are used to improve material handling productivity and to allow more

efficient utilization of space by reducing or eliminating traffic due to forklifts etc. The crane runway

beams are simply supported built-up sections with cap channels. Also, since it’s a built-up member, it

can be tapered – saving the beam costs for large spans.

Mezzanine systemGenerally, the mezzanine framing is connected to the main rigid frame columns for lateral, stability.

Mezzanine beams and joists are analyzed and designed as simple span members. Standard

mezzanine structure consists of built-up beams (that may be tapered for large spans or heavy loads)

that support built-up, hot-rolled or cold-formed mezzanine joists which in-turn support a metal deck.

A reinforced concrete slab is cast on the metal deck as a finished surface. The metal deck is not

designed to carry the floor live loads, it is intended only to carry the reinforced concrete slab during

pouring. The reinforced concrete slab must be designed to carry the floor loads. Interior mezzanine

stub columns are hot rolled tube sections or built-up sections.

Sometimes, in place of concrete flooring, checkered plates or grating may be used. Sometimes, a

structural framing system is mounted on top of the roof and is designed to support heavy roof

accessories, such as HVAC units, water tanks and other miscellaneous roof equipment. These we call

as roof platforms. Also, a narrow walkway, used primarily for maintenance crews to provide access to

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mechanical equipment supported on roof platforms, called as catwalk is provided at times. Catwalk

are usually mounted alongside crane beams, suspended under rigid frame rafters or elevated above

the top of the building roof.

Bracing systemLongitudinal cross bracing, used to provide lateral stability to the structure against wind, seismic or

other forces, comprises of 7-strand twisted galvanized cables with an eye bolt and an adjusting nut

at both ends, located near the outer flange of columns or rafters and attached at the web of the rigid

frame. In buildings supporting cranes, crane longitudinal loads will be transferred to the foundation

using smooth round bars or hot rolled angles in lieu of cables. Also, when the sidewall has to be open

for access etc., portal bracing is provided. For narrow width buildings with low eave heights, the fixed

base column can be designed in the minor axis direction to resist the lateral forces applied along the

length of the building, thus saving the additional bracings. Bracings are usually provided in large roof

area industrial sheds. This is not required for houses.

Paints and finishesNormally the primary and secondary steel are coated with one coat (35 microns) of redoxide paint

without any special treatment to steel. However, if some special paint has to be applied to steel in

order to give better anti-corrosion properties etc. then the steel members have to be shot-blasted

and then coated with the special paints. Also, the other option is for going in for galvanized

secondary steel and hot-dip galvanize the primary steel for better steel properties.

For houses inside painting on walls & ceiling is to be provided.

DOORS AND WINDOWSSteel or aluminium framed doors and windows are fixed to the purlins either by welding or bolted to

the flanges already fixed to the purlins. Proper flashings are applied wherever necessary.

FALSE CEILINGThis is usually required for residential building or offices. A metal frame work is hung from the ceiling

and false ceiling of rigid boards are either bolted or placed over the frame work.

PARTITION WALLSThis is usually required for residential building or offices. Partition wall comprises of two rigid boards

having insulation sandwiched in between and fixed to the steel columns and purlins. Alternatively

prefab sandwich panels can also be fixed to the columns and purlins.

FLOORINGFlooring is usually of conventional nature consisting of cement concrete.

Design CodesDesign codes that govern the design procedures and calculations are as follows :-

Frame members (hot rolled or built-up) are in accordance with AISC (American Institute of

Steel Construction) Specifications for the design, fabrication and erection of structural steel.

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Light gauge cold-formed members are designed in accordance with AISI (American Iron and

Steel Institute) Specification for the design of light gauge cold formed steel structural members.

IS : 8750 – 1987 : Code of practice for design loads of buildings & structures.

IS : 800 -1984 : Code of practice for general construction in steel.

IS : 801- 1975 : Code of practice for use of Cold formed light gauge Steel

Structural Members in general building Construction

Pre-engineered building componentsThe pre-engineered building components headings are almost the same as the conventional

structural steel building components. Apart from the state of the art technology used for fabrication

of pre-engineered buildings, the other main difference is in the assembling of PEB. The varied

components of the PEB are joined to each other based on the nut and bolt methodology as against

the welding and riveting methodology used for structural steel buildings. The nut and bolt system

has the following basic advantages:–

Metal building technologies permit almost complete freedom to the designer and the architect in

incorporating whatever features may be needed in the building-structural, thermal, ventilation or

acoustical, to name a few.

Metal roofing and siding profiles can be manufactured to any length – limited only by transportation

constraints (usually to 12 metres). Lap joints with 150mm to 200mm overlap virtually eliminate

water ingress.

Profiling can be carried out at site itself and, with no limit whatever in lengths that can be rolled.

This permits a totally joint-less run of roofing, a major advantage to the designers to create roofing

with the minimum pitch. Machines have been developed which permit rolling at the eaves level so

that even the task of lifting and shifting the rolled profiles in to position is avoided. Standing seam

profiles with a pre-determined height of up-stands can be chosen to accommodate the expected run-

off of water without overflow on to the crest of the profile.

Pre-engineering of metal buildings can be optimized to meet specific design criteria. Purpose built

buildings such as Hangers for aircraft, Warehouses, Manufacturing and Repair facilities, captive

power plants, cold storages, office buildings, hospitals, living shelters etc. need roof-slung facilities

and utilities imposing localized loads on to the building structure. In automotive manufacturing

plants, high altitude living shelters and cold storages, considerable economies have been registered

by such optimized designs.

Installation of this type of roofing & cladding system can provide 30 years or more of trouble-free

service in most environments.

BENEFITS Optimised design of steel reducing weight

Easy future expansion/modification

Voluminous space (up to 60M clear spans, 30 M eave heights)

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Weather proof.

No fire hazards

International Quality Standards

Seismic & Wind pressure resistant.

Quality design, manufacturing and erection

Quick delivery and Quick turn-key construction.

Architectural versatality

Energy efficient roof and wall system using Rockwool & PUF insulation.

Water-tight roofs & wall coverings

Pre-painted and has low maintenance requirement.

Easy integration of all construction materials

Erection of the building is fast.

The building can be dismantled and relocated easily.

Future extensions can be easily accommodated without much hassle.

Applications:

Applications of pre-engineered steel buildings include (but are not limited to) the following:

Houses & Living Shelters

Factories

Warehouses

Sport Halls

Aircraft Hangers

Supermarkets

Workshops

Distribution Centres

Commercial Showrooms

Restaurants

Office Buildings

Labor Camps

Petrol Pumps/Service Buildings

Schools

Community Centres

Railway Stations

Equipment housing/shelters

Telecommunication shelters

“Almost” any low-rise building

METAL ROOFING & WALL CLADDING SYSTEM DESIGN CONSIDERATIONS

At the initial project planning stage, roof slope is a key consideration for architects incorporating roof

systems into their designs. Slopes as shallow as 1:50 are possible ensuring sufficient drainage of

water and good long term performance of roof panels. Roof design will dictate the minimum slope for

weather tightness. The standing seam roof, for example, can be used at the minimum slope 1:50

(one degree). Its weather tight seams are interlocked together, and raised above the roof’s drainage

plane.

Screw down roofs are installed at slopes of 1:20 and steeper to account for panels being overlapped

at sides and ends, and attached with exposed fasteners.

Minimum Recommended Roof Slope: ½ inch in 12 inches.

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Atmospheric and climate conditions are key elements to consider. Corrosive microenvironments from

local industrial operations can exist that influence the performance of steel roofing. Likewise, marine

exposure can be severe, making the location of the steel roof with respect to the shoreline an

important consideration. Special coatings on steel sheets are available (zincalume, SMP, XRW, PVF )

for corrosive environments.

The base steel is either galvanized having a zinc coating varying from a minimum Mass of 120

gsm./m2 to a maximum of 275 gsm./m2 (total of both sides) or a base steel coating of zinc –

aluminium (zinc 45%, aluminium 55%) of total Mass of 150 gsm./m2 (total of both sides) are

available with permanent colour coating. The colour coating is also available in various options in

polyester paint coating like regular modified polyester, silicon modified polyester and super polyester

coatings. Special organic coatings like PVF (Poly Vinyl Fluoride) are also made available. These

various colour coatings on the base steel with galvanized or zinc aluminium coating provides suitable

resistance for various kinds of environment hazards.

Steel roofs can be successfully used in area subjected to extreme weather conditions (for example,

high winds, heavy rains and snow falls). Manufacturers should be consulted about special designs

and installation details required for such locations. Good quality corrosion-resistant fasteners

(galvanized, SS) should be used on steel roofs. Long life compatible flashings and gutters are also

recommended. Roof top equipment, such as air conditioners and exhaust fans, should be mounted

on roof curbs suitably detailed and installed.

It is important in the planning stage to have options for maximum design flexibility. As an idea

alternative to non-metallic systems, steel roofings can be used for both structural and architectural

roofs since profiles and panels come either unpainted or pre-painted with attractive colours and

finishes.

TYPES OF ROOFING & WALL CLADDING SYSTEMThese profile steel sheets are usually categorized into two types depending upon the type of fixing

arrangement followed. These two types are known as Through Fastened and second one is

Standing Seam. In through fastened roofing or side cladding system, the steel profile panels are

fixed to the structural members by self drilling fasteners either manually or mechanically by a gun.

In this system, the steel sheets are perforated and punctured. These perforated buildings are under

stress due to thermal effects and may cause corrosion if proper grade washer and sealants are not

used. The second system – Standing Seam roofing or cladding differs from through fastened seam,

here the steel sheets are not punctured. A special kind of holding clip made out of galvanized steel is

fixed to the underline steel structure and the profile steel sheets are pressed over the clips and gets

locked. The steel profile sheets are held together and secured to the clips by a mechanical seam.

These clips permit the steel sheets to move or float over the structure to bear thermal expansion and

contraction brought on by the seasonal changes. Since the steel sheets are not punctured hence

there is no chance of any corrosion taking place. With the availability of modern roll forming

2

2

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technology, the profiling machine can be installed at the site and long length profile sheets can be

manufactured at site (greater than 12 metre). This makes very quick installation.

The Standing Seam roof design can be used for near flat sloping roof buildings (as low as 1 ). For

such roofs, bare profile steel sheets (un-quoted) can be used for economic reasons as the roof slope

is virtually not visible from outside. In Standing Seam roofing, there is only one jointing between the

steel sheets that is the longitudinal joint, whereas in case of through f astened system, there is also

an overlap horizontally. Usually the longitudinal overlap is of one profile (the profile of one sheet

exactly rests over the profile of the over sheet) and the horizontal overlapping is minimum 150mm.

The fasteners are fixed on the crests for roofing and on the valley for side cladding. The fasteners

usually are galvanized and sometimes SS.

Steel roof buildings applicable to both residential and non residential buildings are lighter in weight,

easier to install, highly resistant to environmental damage due to windage, rain, snow, marine

atmosphere and free of frequent maintenance and repairs. The life is also quite substantial.

However, residential roofing requires a more aesthetic pleasing appearance. Various types of roofing

and side cladding design is possible in a combination of various colours by steel sheets. The steel

sheets can be rounded or crimp curved for providing typical shape and finish to the building. Because

of the light weight of the steel sheet, the steel structure underneath can be possible with a lower

weight. Taking advantage of this proper insulation system can be fixed below the roofing sheets and

the siding walls. The underneath steel structure can be used for placing fibrous insulation material

like resin bonded rockwool laminated suitably and held in position with the help of a metallic mesh or

a rigid packing. This insulation layer underneath caters to thermal insulation as well as sound barrier

from outside. Such insulation reduces the noise level from outside and keeps out heat during

summer and cold during winter.

SANDWICH PANELSIn addition to the above single sheet profiles, sandwich panels also find extensive use in residential

as well as non-residential buildings. In sandwich panels two profile steel sheets having insulation in

between are used. The insulation can be a fibrous rockwool or a rigid material like polyurethane

foam. These sandwich panels can be factory made and sent to the site as a single piece material or

fabricated at site. These panels are light weight, rigid and results in very fast erection. The panels

provide sufficient insulation and noise reduction properties.

Nowadays large cold storage units (Potato, Onion, vegetables, processed foods etc.) are also made

with this pre-engineered building technique. For this application ‘Sandwich Panels’ featuring a core of

high efficiency insulation like Polyurethane is used. The inner and outer surface of the panel elements

are made up of hot dipped galvanized or zincalume coated pre-painted steel sheets. The steel sheet

has light cutting grooves in order to give extra strength as well as to enhance the appearance of the

cladding.

Many industrial enclosures call for acoustical barrier – value to be possessed by the building cladding

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and roofing. In addition, internal absorption may be called for to reduce internally built up noise. It is

easy to feature these attributes while featuring metal building concepts by installation of high density

Rockwool Slabs insulation underneath the cladding / roofing sheet or sandwiched between two steel

profiled sheets.

ERECTIONSteel framing members are delivered at site in pre-cut sizes, which eliminates cutting and welding at

site. Being lighter in weight, the small members can be very easily assembled, bolted and raised

with the help of cranes. This system allows very fast construction and reduces wastage and labour

requirement. These buildings can then be provided with roof decking and wall cladding with metal

profile sheets and proper insulation. The framing are so designed that electrical and plumbing

services are part of it and can be very easily concealed.

MAINTENANCEIn PEB the maintenance area is the steel roofing & cladding.

Steel roofing & side wall cladding requires minimum maintenance. The roof should be inspected

immediately after installation to check if cleaning of the roof has been carried out fully. It is very

often seen that the drilled out metal and debris are not swept away. These can act as initiators of

corrosion and lead to premature failures.

Installed roofing must be inspected atleast once a year. Any exposed metal that can rust or has

rusted should be painted. Leaves, branches, and trash should be removed from gutters, at ridge

caps and in corners. Also watch out for discharge from industrial stacks, and particulate matter and

high sulphur exhaust from space heaters which could get piled up.

Roof top ancillaries and air conditoner supports, drains and housing should be checked. Particular

attention should be paid to add-on roof ancillaries that create new roof penetrations. Roof-top air

conditioners should be installed on curbs designed to avoid ponding water. Condensate from air –

conditioning and refrigeration equipment should never be allowed to drain directly on to the roof

panels. The drainage contains ions from condenser coils that accelerate corrosion.

In the event of a roof leak, do not indiscriminately plaster the suspected leak area with tar or

asphalt or use repair tape. Water can collect under the repair material causing corrosion. Instead,

have an experienced roofing foreman locate the leak, identify its cause and properly repair the roof.

CONCLUSIONSteel is a preferred material for construction, due to its various advantages like quality, aesthetics,

economy and environmental conditions. This concept can have lot of scope in India, which can

actually fill up the critical shortage of housing, educational and health care institutions, airports,

railway stations, industrial buildings & cold storages etc. Pre-engineered Metal building concept forms

an unique position in the construction industry in view of their being ideally suited to the needs of

modern Engineering Industry. It would be the only solution for large industrial enclosures having

thermal and acoustical features. The major advantage of metal building is the high speed of design

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Home Building Technology

PRE-CONCRETE CHECKS FOR FORMWORK &RELEASE AGENTS

PRE-CONCRETE CHECKS FORFORMWORK:

Before the concrete is poured into the formwork, it

must be checked by someone who has been trained

to inspect formwork. Depending on how big or

complicated the pour is, the inspection may just take

few minutes or it could take hours. Only when the

formwork has been approved, may the pour take

place.

Formwork pressures are function of height (including

the height from which concrete is dropped into the

forms) and are affected by concrete workability, rate of stiffening and rate of placing. One task of

the temporary works co-ordinator is to consider such factors as ambient temperatures and concrete

composition, when calculating maximum permissible rate of concrete placing.

Exceeding this limit may lead to unacceptable formwork deflections, loss of grout / concrete at joints,

or even collapse. The cost of remedial work due to formwork deflection will usually exceed the

original cost of doing the job properly.

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clip_image002Below are the checks that should be verified before pouring begins:

Is the formwork erected in accordance with the approved drawings?

Is the formwork restrained against movement in all directions?

Is it correctly aligned and leveled?

Are all the props plum, and at the right spacing?

Are bolts and wedges secure against any possible looseing?

Has the correct number of ties been used? Are they in the right places and properly tightened?

Are all inserts and cast-in fixings in the right position and secure?

Have all stop ends been properly secured?

Have all the joints been sealed to stop grout loss (especially where the formwork is against the

kicker)?

Can the formwork be struck without damaging the concrete?

Are the forms clean and free from rubbish such as tie wire cuttings, and odd bits of timber or

metal?

Has the release agents been applied, and is it the correct one?

Are all projecting bars straight and correctly positioned?

Is there proper access for placing the concrete and compacting?

Have all the toe-boards and guard rails been provided?

RELEASE AGENTS FOR FORMWORK:

Formwork needs to be treated with a release agent so that it can be removed easily after the

concrete has set. Failure to use a release agent can result in the formwork sticking to the concrete,

which may lead to damage of the concrete surface when it is prised off.

A single application of release agent is all that is required when forms are then used. Care must be

taken to cover all the surface that will come in contact with the surface of concrete. However, if

there is an excess of release agent, it may cause staining or retardation of the concrete.

There are different release agents depending on what material is used for the formwork. The three

most common release agents for formwork are:

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ULTRA-HIGH PERFORMANCE CONCRETE(UHPC)

1. Neat oils with surfactants: used mainly on steel surfaces, but also suitable for timber and plywood.

2. Mould cream emulsions: good general purpose release agents for use on timber and plywood.

3. Chemical release agents: recommended for high quality work, applied by spray to all types of

form face.

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PREPARATION OF APPROXIMATE CONSTRUCTION ESTIMATE

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construction-estimation

PREPARATION OF APPROXIMATECONSTRUCTION ESTIMATE

Preliminary or approximate estimate is required for

studies of various aspects of work of project and for

its administrative approval. It can decide, in case of

commercial projects, whether the net income earned

justifies the amount invested or not. The

approximate estimate is prepared from the practical

knowledge and cost of similar works. The estimate is

accompanied by a report duly explaining necessity

and utility of the project and with a site or layout

plan. A percentage 5 to 10% is allowed for

contingencies.

The following are the

methods used for

preparation of approximate estimates:

a) Plinth area method

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b) Cubical contents methods

c) Unit base method.

a) Plinth area method:

The cost of construction is determined by multiplying plinth area with plinth area rate. The area is

obtained by multiplying length and breadth (outer dimensions of building). In fixing the plinth area

rate, careful observation and necessary enquiries are made in respect of quality and quantity aspect

of materials and labour, type of foundation, height of building, roof, wood work, fixtures, number of

storeys etc.

As per IS 3861-1966, the following areas include while calculating the plinth area of

building:

Types of Estimates

Area of walls at floor level.

Internal shafts of sanitary installations not exceeding 2.0 sqm, lifts, air-conditioning ducts etc.,

Area of barsati at terrace level: Barsati means any covered space open on one side, constructed

on one side, constructed on terraced roof which is used as shelter during rainy season.

Porches of non-cantilever type.

Areas which are not to include

Area of lofts.

Unenclosed balconies.

Architectural bands, cornices etc.,

Domes, towers projecting above terrace level.

Box louvers and vertical sun breakers.

b) Cubical Contents Method:

This method is generally used for multi-storeyed buildings. It is more accurate that the other two

methods viz., plinth area method and unit base method. The cost of a structure is calculated

approximately as the total cubical contents (Volume of buildings) multiplied by Local Cubic Rate. The

volume of building is obtained by Length x breadth x depth or height. The length and breadth are

measured out to out of walls excluding the plinth off set.

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TAGS Construction Costing Construction Estimates

The cost of string course, cornice, corbelling etc., is neglected.

The cost of building = volume of buildings x rate/ unit volume.

c) Unit Base Method:

According to this method the cost of structure is determined by multiplying the total number of units

with unit rate of each item. In case schools and colleges, the unit considered to be as ‘one student’

and in case of hospital, the unit is ‘one bed’. The unit rate is calculated by dividing the actual

expenditure incurred or cost of similar building in the nearby locality by the number of units.

Also Read: PREPARATION OF DETAILED CONSTRUCTION ESTIMATE

Download: Cost Estimation in a Construction Company

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PREPARATION OF DETAILED CONSTRUCTION ESTIMATE

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PREPARATION OF DETAILED CONSTRUCTIONESTIMATE

The preparations of detailed estimate consist of

working out quantities of various items of work and

then determine the cost of each item. This is

prepared in two stages.

i) Details of measurements and calculationof quantities:

The complete work is divided into various items of

work such as earth work concreting, brick work,

R.C.C. Plastering etc., The details of measurements

are taken from drawings and entered in respective

columns of prescribed proforma. The quantities are

calculated by multiplying the values that are in numbers column to Depth column as shown below:

Details of measurements form

Details of measurements form

ii) Abstract of Estimated Cost:

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PREPARATION OF DETAILED CONSTRUCTION ESTIMATE

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The cost of each item of work is worked out from the quantities that already computed in the detals

measurement form at workable rate. But the total cost is worked out in the prescribed form is known

as abstract of estimated form. 4%of estimated Cost is allowed for Petty Supervision, contingencies

and unforeseen items.

Abstract of Estimate Form

The detailed estimate should be accompanied with:

i) Report

ii) Specification

iii) Drawings (plans, elevation, sections)

iv) Design charts and calculations

v) Standard schedule of rates.

Factors to be considered while Preparing Detailed Estimate:

i) Quantity and transportation of materials: For bigger project, the requirement of materials is more.

Such bulk volume of materials will be purchased and transported definitely at cheaper rate.

ii) Location of site: The site of work is selected, such that it should reduce damage or in transit

during loading, unloading, stocking of materials.

iii) Local labour charges: The skill, suitability and wages of local laboures are considered while

preparing the detailed estimate.

Data for detailed estimate:

The process of working out the cost or rate per unit of each item is called as Data. In preparation of

Data, the rates of materials and labour are obtained from current standard scheduled of rates and

PREPARATION OF DETAILED CONSTRUCTION ESTIMATE

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TAGS Construction Estimates Cost Estimate Detailed Estimate

while the quantities of materials and labour required for one unit of item are taken from Standard

Data Book (S.D.B).

Fixing of Rate per Unit of an Item:

The rate per unit of an item includes the following:

1) Quantity of materials & cost: The requirement of materials is taken strictly in accordance with

standard data book (S.D.B). The cost of these includes first cost, freight, insurance and

transportation charges.

ii) Cost of labour: The exact number of labourers required for unit of work and the multiplied by the

wages/ day to get of labour for unit item work.

iii) Cost of equipment (T&P): Some works need special type of equipment, tools and plant. In such

case, an amount of 1 to 2% of estimated cost is provided.

iv) Overhead charges: To meet expenses of office rent, depreciation of equipment salaries of staff

postage, lighting an amount of 4% of estimate cost is allocated.

PREPARING CONTRACT (TENDER) DOCUMENTS

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PREPARING CONTRACT (TENDER) DOCUMENTS

A contract or tender document in construction

industry is an agreement between two parties which

they intend to be legally binding with respect to the

obligations of each party to the other and their

liabilities. The contract thus binds the contractor to

construct the works as defined, and the employer to

pay for them in the manner and timing set out.

Contract documents

As civil engineering works are often complex,

involving the contractor in many hundreds of

different operations using many different materials

and manufactured items, including employment of a wide variety of specialists, the documents

defining the contract are complex and comprehensive. The task of preparing them for tendering

therefore warrants close attention to detail and uniformity of approach, so as to achieve a coherent

set of documents which forms an unambiguous and manageable contract. A typical set of documents

prepared for tendering will include the following.

Instructions to tenderers

These tell the contractor where and when he must deliver his tender and what matters he must fill in

to provide information on guarantees, bond, proposed methods for construction, etc. The instructions

may also inform him of items which will be supplied by the employer, and sources of materials he

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should use (e.g. source of filling for earthworks construction, etc.).

General and particular conditions of contract

The general conditions of contract may comprise any of the ‘standard’ forms of contract. The

particular conditions adopted may contain amendments or additions that the employer wishes to

make to the standard conditions. Usually the standard conditions (which are available in printed

form) are not reproduced in the tender documents but they will be named by specific reference and a

schedule will show what changes have been made to them.

The specification

This describes in words the works required, the quality of materials and workmanship to be used,

and methods of testing to be adopted to ensure compliance. The specification usually starts with a

description of the works to be constructed, followed by all relevant data concerning the site, access,

past records of weather, etc. and availability of various services such as water supply, electric power,

etc.

Bill of quantities or schedule of prices

These form an itemized list covering the works to be constructed, against each item of which the

tenderer has to quote a price. A bill of quantities shows the number or quantity of each item and its

unit of measure, the rate per unit of quantity quoted by the tenderer, and the consequent total price

for that item. This permits re-measure according to the actual quantity done under each item. Some

bills contain many hundreds of items, classified by trade or according to a standard method of

measurement; other bills contain a less number of items. A schedule of prices may comprise a series

of lump sums or it may call for rates only, but can list provisional quantities which are estimated,

that is, uncertain. They would be used, for instance, for a contract for sinking boreholes, items being

provided for boring in stages of depth, the total depth to which any hole has to be sunk not being

known in advance.

PREPARING CONTRACT (TENDER) DOCUMENTS

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Tender and appendices

The tender sets out the formal wording which comprises the tenderer’s offer to undertake the

contract, the tenderer having to enter the sum price he offers. The appendices to tender will contain

other matters defining the contract terms and which the tenderer confirms he accepts in making his

offer, such as time for completion of the works, damages for failure to complete on time, minimum

amount of insurances, completion of bond, etc. There may be other matters concerning the basis of

his offer he is required to supply, such as currency exchange rates (for international contracts) or

sources of materials.

The contract drawings

These should provide as complete a picture as possible of all the works to be built. The more

complete the contract drawings are, the more accurately the contractor can price the work, and the

less likelihood there is that variations and extra payments will be necessary. However, it is not

necessary at tender stage to provide every detailed drawing that will ultimately be required (such as

all concrete reinforcement drawings) so long as the contract drawings provided to tenderers show

quite clearly what is required.

On small jobs all the foregoing documents may be combined in one volume; but on most jobs at

least two and sometimes three or more volumes will be necessary. A tenderer is usually sent a

second copy of the instructions to tenderers, bill of quantities, tender and appendices, so that he can

keep one copy of what he has bid.

PROJECT MANAGEMENT TERMS & DEFINITIONS

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PROJECT MANAGEMENT TERMS & DEFINITIONS

Microsoft Project is a project management system,

which assist the project managers to execute and

control the project activities effectively in order to

meet the sponsors needs and expectations from a

project.

Project management involves the planning,

scheduling and controlling of the activities in a

project

Project Management Terms

Planning – Defining the objectives of the project and listing the tasks.

Scheduling – Arranging the tasks in the order in which they are to be performed and allocating

the resources.

Controlling – Calculating the optimum, durations of each activity and quantity of resources to

bring out the successful completion of the project.

Network planning technique can be used for project management. In this technique large

projects are broken down to individual jobs or events and arranged in logical network. Network

planning helps in planning, scheduling and controlling, in order to complete the project economically

in minimum available time with limited available resources.

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PROJECT MANAGEMENT TERMS & DEFINITIONS

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The important terms related to project planning are:

Event

An event is a specific instant of time, which makes the start or end of an activity. Event consumes

neither time nor resources.

Activity

An activity is the actual performance of the task and requires time and resources for its completion.

It is the work required to complete a specific task.

Predecessor activity

The activity proceeding to any given activity is called the predecessor activity.

Successor activity

The activity succeeding to any given activity is called the successor activity.

Duration

Duration is the estimated or actual time required to complete a task or an activity.

Earliest start time (EST)

It is defined as the earliest possible time at which an activity can start. It is calculated by moving

from first to last event in a network diagram.

Earliest finish time (EFT)

It is the earliest possible time at which an activity can finish.

PROJECT MANAGEMENT TERMS & DEFINITIONS

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EFT = EST + duration of that activity.

Latest finish time (LFT)

It is calculated by moving from last event to the first event of the network diagram.

Latest start time

It is the latest possible time by which an activity can start.

LST = LFT – duration of that activity.

Float or Slack

Stack is with reference to an event and float is with reference to an activity. Float is the difference

between time available for completing an activity and the time necessary to complete an activity.

Total Float

It is the time span by which the starting and finishing an activity can be delayed without delaying

the completion of the project. It is the additional time, which a non critical activity can consume

without increasing the project duration.

Critical path

It is the sequence of critical activities, which decide the total project duration. A critical path

consumes maximum resources. It is the longest path and consumes maximum time. It is the one,

which connects the events having zero minimum float.

PERT (Project Evaluation and Review Technique)

It is a probabilistic model with uncertainty in activity duration. It is an event oriented approach used

for planning, controlling and reviewing the project. The expected time for each activity can be

calculated using three time estimates-

Optimistic time (t )

Most likely time (t )

o

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PROJECT MANAGEMENT TERMS & DEFINITIONS

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Pessimistic time (t )

It is used to find the applications in projects where resources(3m – en, materials and money) are

always made available as and when required.

CPM (Critical Path Method)

CPM is a deterministic model with well known activity time based upon past experience. It assumes

that , the expected time is actually the time taken. It is an activity oriented system and marks the

critical activities. CPM is employed to those projects where minimum overall cost is important and

there is better utilization of resources.

Network Updating

It is defined as an adjustment to the network diagram, which becomes necessary owing to departure

from the project schedule laid down earlier. It is the process of incorporating the changes in the

network, which have occurred due to planning and rescheduling.

Resource

A resource is a physical variable such as labour, finance, equipment and space, which will impose

limitation on time for the project.

Resource Smoothing

This implies scheduling the activities within the limit of their total float, such that fluctuations in the

resource requirements are minimized. In resource smoothing the main constraint is the project

duration time. But the activities having floats are shifted so that a uniform demand on the resources

is achieved.

Resource Leveling

In resource leveling, the main constraint would be the resources and if the maximum demand on

any resource is not exceed a certain limit, the activities will then have to be rescheduled so that the

total demand on the resource at any time will be within the limit. The project duration time

consequently is exceeded.

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PROJECT QUALITY MANAGEMENT IN CONSTRUCTION

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PROJECT QUALITY MANAGEMENT INCONSTRUCTION

Project quality management in construction has

become essential in modern construction practices

and has incorporated quality management principles

and initiatives in their activities. Quality management

systems such as ISO 9000 series of standards require

incessant monitoring of construction processes.

Many quality management tools are available for

quality management in construction. Detailed

analysis using these tools provides opportunities for

improvements in costing and time deadline issues.

Critical areas can be studied by WBS and functional

unit analysis focused in the main activities.

Problem solving for quality management in construction can be achieved by tools like combination of

brainstorming sessions, Fishbone diagrams and Pareto analysis.

It is common for a construction project to get delayed and reason for the same can be many. It is

essential to analyze the various factors which contribute to the delaying a project. Doing the analysis

in a scientific manner, the impact, timing and the contributing effects of each the causes for the

construction project delay can be studied and prevented.

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PROJECT QUALITY MANAGEMENT IN CONSTRUCTION

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The delay in construction project execution can become a burden for construction companies as they

may have to pay the owners fine for the delay as per the terms of the contract. So, the analysis

becomes necessary to avoid those fines.

Following are the methods to track the Project Scheduling:

Gantt chart

Also Called milestones chart, project bar chart, activity chart. A Gantt chart is a bar chart that shows

the tasks of a project, when each must take place and how long each will take. As the project

progresses, bars are shaded to show which tasks have been completed. People assigned to each task

also can be represented. When to Use:

When scheduling and monitoring tasks within a project.

When communicating plans or status of a project.

When the steps of the project or process, their sequence and their duration are known.

When it’s not necessary to show which tasks depend on completion of previous tasks.

Project management software

Primavera Project Planner

i. Control large and complex projects efficiently. Primavera is designed to handle large-scale, highly

sophisticated and multifaceted projects. To organize projects up to 100,000 activities, P3 provides

unlimited resources and an unlimited number of target plans. Massive data requires sophisticated,

yet highly flexible organization tools. P3 gives you a multitude of ways to organize, filter and sort

activities, projects, and resources.

ii. Manage multiple projects in a multiuser environment. Large, multi-disciplined project teams. High

intensity, short duration projects. Critical projects sharing limited resources. Primavera can help

manage them all. It offers a single database solution (ODBC-compliant) that provides simultaneous

access to project files by multiple users throughout the project; whenever and wherever required.

Web features also make it easy to keep the whole team informed.

iii. Compatible with other programs in the corporation. Primavera offers impressive capability for

PROJECT QUALITY MANAGEMENT IN CONSTRUCTION

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integrating its data with information throughout the company. It supports a wide variety of data

exchange formats. You can cut and paste with other Windows applications, or use Object Linking and

Embedding (OLE) to link information from other applications. P3 provides true Client/Server

operation for accelerated processing and SQL access for reporting on the project database.

Construction Project Quality Tools:

Some of the most important and most commonly used quality tools are:

Plan–Do–Check–Act Cycle

Fishbone Diagram

Pareto Chart

Scatter Diagram

Decision Matrix

Flowchart

Stratification

Control Chart

Histogram

Brainstorming

Tree Diagram

Construction Project Progress

fig.:Pareto Analysis of Construction Project Activities

fig: Pareto Analysis of Construction Project Activities

PROJECT QUALITY MANAGEMENT IN CONSTRUCTION

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TAGS Construction Management Construction Project Quality Quality Management

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PLANNING, SCHEDULING AND CONSTRUCTIONMANAGEMENT

Fig: Pareto Analysis of Construction Project Activities

Fishbone Analysis

Cause and Effect Diagram – Fishbone Analysis of the COST

Cause and Effect Diagram – Fishbone Analysis of the DELAYS

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PROTECTION OF BUILDINGS AGAINST DAMPNESS

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PROTECTION OF BUILDINGS AGAINSTDAMPNESS

PROTECTION OF BUILDINGS AGAINSTDAMPNESS

One of the requirements of the building is that it

should be dry. Dampness in a building may occur due

to bad design, faulty construction and use of poor

quality of materials. Dampness not only affects the

life of the building but also creates unhygienic

conditions of the important items of work in the

construction of a building. The treatment given to

prevent leakage of water from roof is generally

termed as water proofing whereas the treatment

given to keep the walls, floors and basement dry is

termed as damp proofing.

DEFECTS OF DAMPNESS IN BUILDINGS:

The various defects caused by dampness to building may be summarized as under:

1. It causes efflorescence which may ultimately result in disintegration of bricks, stones, tiles etc.

2. It may result in softening and crumbling of plaster.

3. It may cause bleaching and flaking of paint with the formation of coloured patches.

4. It may result in the warping, buckling and rotting of timber.

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5. It may lead to the corrosion of metals.

6. It may cause deterioration to electrical fittings.

7. It promotes growth of termites.

8. It creates unhealthy living conditions for the occupants.

CAUSES OF DAMPNESS IN BUILDINGS

Absorption of moisture by the building materials is one of the chief causes of dampness. On acoount

of granular nature of materials, moisture finds an easy access through the voids and this aided by

capillary action assists the moisture to travel in different directions. Thus, either on account of faulty

design of structure or bad workmanship or by use of defective structures or by use of defective

materials, moisture may find its way on the interior of the building either through the wall, floor or

roof.

SOURCES OF DAMPNESS IN BUILDINGS

The important sources of dampness may be summarized as below:

1. Dampness rising through the foundation walling. Moisture from wet ground may rise well above

the ground level on account of capillary action.

2. Splashing rain water which rebounds after hitting the wall surface may also cause dampness.

3. Penetration of rain water through unprotected tops of walls, parapet, compound walls, etc may

cause dampness.

4. In case of sloped roofs, rain water may percolate through defective roof covering. In addition

faulty eaves course and eave or valley gutters may allow the rain water to descend through the

top supporting wall and cause dampness.

5. In case of flat roofs, inadequate roof slopes, improper rain water pipe connections, and defective

junction between roof slab and parapet wall may prove to be the source of dampness.

METHODS OF DAMP PROOFING

Following methods are generally adopted to prevent the defect of dampness in a structure:

1. Membrane damp proofing

PROTECTION OF BUILDINGS AGAINST DAMPNESS

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2. Integral damp proofing

3. Surface treatment

4. Guniting

5. Cavity wall construction

(1) Membrane Damp Proofing:

This consists in providing layers of membrane of water repellant material between the source of

dampness and the part of the structure adjacent to it. This type of layer is commonly known as dam

proof course (or DPC) and it may comprise of materials like bituminous felts, mastic, asphalt,

plastic or polythene sheets, cement concrete, etc. Depending upon the source of dampness, DPC

may be provided horizontally or vertically in floors, walls, etc. Provision of DPC in basement is

normally termed as tanking.

General principles to be observed while laying DPC are:

1. The DPC should cover full thickness of walls excluding rendering.

2. The mortar bed upon which the DPC is to be laid should be made level, even and free from

projections. Uneven base is likely to cause damage to DPC.

3. When a horizontal DPC is to be continued up a vertical face a cement concrete fillet 75mm in

radius should be provided at the junction prior to the treatment.

4. Each DPC should be placed in correct relation to other DPC so as to ensure complete and

continuous barrier to the passage of water from floors, walls or roof.

(2) Integral Damp Proofing:

This consists in adding certain water proofing compounds with the concrete mix to increase its

impermeability. Such compounds are available in market in powdered as well as in liquid forms.

The compounds made from clay, sand or lime (chalk, fuller’s earth, etc) help to fill the voids in

concrete and make it water proof.

Another form of compounds like alkaline silicates, aluminium sulphates, calcium chlorides, etc react

chemically when mixed with concrete to produce water proof concrete.

Pudlo, Imperno, Siks, etc. are some of the many commercially made preparation of water proofing

compounds commonly used. The quantity of water proofing compounds to be added to cement

depends upon manufacturers’ recommendations. In general, one kg of water proofing compound is

PROTECTION OF BUILDINGS AGAINST DAMPNESS

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added with one bag of cement to render the mortar or concrete water proof.

(3) Surface Treatment:

As described earlier, the moisture finds its way through the pores of materials used in finishing. In

order to check the entry of the moisture into the pores, they must be filled up. Surface treatment

consists in filling up the pores of the surfaces subjected to dampness. The use of water repellant

metallic soaps such as calcium and aluminium oleates and stearates is such effective in protecting

the building against the ravages of heavy rain. Bituminous solution, cement coating,

transparent coatings, paints, varnishes fall under this category. In addition to other surface

treatment given to walls, the one economically used is lime cement plaster. The walls plastered with

cement, lime and sand in proportion of 1:3:6 is found to serve the purpose of preventing dampness

in wall due to rain effectively.

(4) Guniting:

This consists in depositing an impervious layer of rich cement mortar over the surface to be water

proofed. The operation is carried out by use of a machine known as cement gun. The assembly

broadly consists of a machine having arrangements for mixing materials and a compressor for

forcing the mixture under pressure through a 50mm diameter flexible hose pipe. The hose pipe has

nozzle at its free end to which water is supplied under pressure through a separate connection.

The surface to be treated is first thoroughly cleaned of dirt, dust, grease or loose particles and

wetted properly. Cement and sand (or fine aggregates) usually taken in proportion of 1:3 to 1:4 are

then fed into the machine. This mixture is finally shot on the prepared surface under a pressure of 2

to 3 kg per square cm by holding the nozzle of the cement gun at the distance of 75 to 90 cm from

the working surface. The quantity of water in the mix can be controlled by means of regulating valve

provided in the water supply hose attachment. Since the material is applied under pressure, it

ensures dense compaction and better adhesion of the rich cement mortar and hence treated surface

becomes water proof.

(5) Cavity Wall Construction;

This consists in shielding the main wall of the building by an outer skin wall leaving a cavity in

between the two. The cavity prevents the moisture from traveling from the outer to the inner wall.

QUALITY ASSURANCE OF CONSTRUCTION MATERIALS

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QUALITY ASSURANCE OF CONSTRUCTIONMATERIALS

Quality assurance of construction materials is

the responsibility of the purchase department to

assure the quality of purchased materials in

consultation with production and engineering

department. Proper specifications have to be decided

and finally conveyed as part of purchase orders.

The characteristics/standards of the construction

materials need to be put down in purchase orders in

unambiguous items. The technical terms should

uniquely be understood by the supplier. The testing

and inspection methods/procedures, the type of tests

that are required to be conducted; all need to be

specified accurately.

Quality assurance of construction materials

The purchase department can achieve required quality of incoming construction material

by:

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QUALITY ASSURANCE OF CONSTRUCTION MATERIALS

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(a) Conveying correct specifications,

(b) Assessing quality capability of supplier before placement of purchase order,

(c) Frequent testing and inspection at the supplier’s production facilities, if considered necessary,

(d) Insisting on proper certification of dispatched material from the supplier’s facility,

(e) Proper packaging and transportation to avoid deterioration, damage, breakage during transition,

(f) Testing and inspection at the receiving end. Insisting on approved quantity and quality certificate

by receiving point so as to release the payment,

(g) Proper storage in the warehouse/store so as to avoid deterioration or damage during storage,

and

(h) Revising and conveying the quality specification as and when needed well in advance so as to

avoid stockpiling and or getting mixed up of ‘old’ quality items with ‘new’ quality items.

All these steps, used appropriately, help in insuring the right quality of the incoming construction

materials; which ultimately reflects in the final product of the company.

Quality in Construction

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Quality in Construction

Quality in construction is defined as ‘meeting or

exceeding the requirement of client/owners. In

construction industry, quality is used in different

every than the product industry. In the product

industry, quality of some product is better than the

other, but we can not say that one grade of concrete.

Quality in construction is employed with conformity

with which specifications are met.

Designer specifies the grade of concrete to be used

and contractor has to use the in gradients of

concrete such that desired grade of concrete is

obtained.

Quality in construction is related to

satisfying the specification mentioned in the contract

completing the project time.

Fulfilling the owner’s requirement within budget

Avoiding disputes claims and

Ensuring the faculties performs its intended purpose.

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Quality in Construction

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We use certain product in the construction industry such as tiles, brick. Quality of these products can

be partially related with the general connotation of quality. Other aspect in quality has slightly

different meaning at various stages of life cycle of product such as at design stage or construction

stage.

Quality schemes involve economic studies of selection of types of material and methods to be

included in design , ensuring that this design is in accordance with all applicable codes and regulation

and controlling the construction on the project to be sure that the work is performed according to

the standards specified in the contract documents . Method to be adopted may vary from the

automated documented through computer to statistical quality control in the field.

Quality Assurance

Quality assurance is referred as a scheme adopted by a construction company to maintain the

standard or quality consistent. It is primarily an internal management system of a construction

company. Generally a company maintains a quality assurance chart by specify various checks at

different levels as well as constantly improving its attributes. A quality assurance program may

include

Arranging periodical training for its worker

a good safety Programme

a sound procurement system to get best quality material and suppliers

A reward scheme for innovative work and competitive career progress scheme

If a company is involved in repetitive work, then implementations of statistical control of the

process. Such as in concreting, regular sampling scheme control the production of concrete. Similarly

in asphalt work , regular satisfied quality control is carried out.

Quality Control

Quality control is the periodic inspection to ensure that the constructed facilities meet the standard

specified in the contract. It is usually carried by team of owners engineers or its morning. As for

example, in a high way project, engineers check that compaction of soil is carried out properly by

measuring its density; workability of concrete is checked by employing slump test etc. or checking

compressive strength of concrete at periodical level.

Quality in Construction

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Quality assurance is good management scheme whereas quality control is an inspection or sampling

process.

Government works is generally carried out using lowest bid system. In lowest bid system, high

quality work carried out by contractor does not play a major role rather price quoted by them is an

important criteria.

The procedure for selection of contractor affects the quality control in the construction. Low bid

system hardly provides any incentive to high quality work carried out by the contractor. Government

organizations are highly their hard to improve the low bid system.

Quality control includes

1. Setting up specific standard for construction

2. Checking the deviation from the standard

3. Taking action to correct or minimize the variation

4. Improvement of the standard.

Quality Standardization

ISO 9000 standards fix the standard for quality. ISO stands for International organization for

standardization. This organization founded in Switzerland in 1947. Similar standards for Indian

context are IS 14000 – 04.

ISO 9000 series of standard are quality assurance standard that assures client that the organization

having obtained the certification works according to specified requirement.

It stands for system standardization and certification. Emphasis is given to defining and laying down

the procedure, process etc in the form of documents.

ISO is important because it offers an internationally recognized systematic approach, coupled with

institutionalization of the institutes, policies, procedures, record keeping, technologies and resources

for managing quality work.

Basic principles advocated by ISO are –

1. Focus on customer

2. Provide leadership

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1. Involve your people

2. Use a process approach

3. Take a systematic approach

4. Encourage continual improvement

5. Get the facts before you decide

6. Work with your supplier

ISO 9000 series standards are –

ISO 9000

ISO 9001

ISO 9002

ISO 9003

ISO 9004

Elements of Quality

The basic element of quality in construction is

1. Quality characteristics

2. Quality of design

3. Quality of conformance

A quality characteristic is related to the parameters with respect to which quality – control

processes are judged. Quality characteristic includes strength, colors, texture, dimension, height etc.

Example in compressive strength of concrete, usability of concrete in slump, etc.

Quality of design:- It refers to the quality with which the design is carried out. It primarily related

to meeting the requirement of the standard, functionally efficient system and economical

maintainable system.

Quality of conformance:- It is referred to the degree to which the constructed facility conformed

the design and specification. Quality of conformance is affected by-

1. field construction methodology

2. Inspection

Economics of Quality of design

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Quality of design is generally evaluated based on economics of quality. There are two aspects of

economics of quality design

1. value addition of quality

2. cost of quality

With the increase of quality of design, dost increase is exponential but value addition initially

increases, but starts saturating at of some point. Hence the optimum cost is arrived when slope

of both the curves is same.

Quality in Construction

The economics of quality conformance is shown in the figure. One can note that with the increase of

quality of construction, cost of quality control gets saturated. Thus we can arrive at optimum quality

for minimum cost from total cost of the construction. This has been shown in the figure.

Quality in 20Construction

IS Code provision for quality control of concrete

IS 456 provides the schemes for quality control and quality assurance of concrete, we have

reproduced the clauses –

Clause 10.1 Quality Assurance Measures

Clause 10.1.1 In order that the properties of the completed structure be consistent with the

requirements and the assumptions made during the planning and the design, adequate quality

assurance measures shall be taken. The construction should result in satisfactory strength,

serviceability and long term durability so as to lower the overall life-cycle cost. Quality assurance in

construction activity relates to proper design, use of adequate materials and components to be

supplied by the producers, proper workmanship in the execution of works by the contractor and

ultimately proper care during the use of structure including timely maintenance and repair by the

owner.

Clause 10.1.2 Quality assurance measures are both technical and organizational. Some common

cases should be specified in a general Quality Assurance Plan which shall identify the key elements

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necessary to provide fitness of the structure and the means by which they are to be provided and

measured with the overall purpose to provide confidence that the realized project will work

satisfactorily in service fulfilling intended needs. The job of quality control and quality assurance

would involve quality audit of both the inputs as well as the outputs. Inputs are in the form of

materials for concrete; workmanship in all stages of batching, mixing, transportation, placing,

compaction and curing; and the related plant, machinery and equipments ; resulting in the output in

the form of concrete in place. To ensure proper performance, it is necessary that each step in

concreting, which will be covered, by the next step is inspected as the work proceeds (see also 17).

15 SAMPLING AND STRENGTH OF DESIGNED CONCRETE MIX

15.1 General

Samples from fresh concrete shall be taken as per IS 1199 and cubes shall be made, cured and

tested at 28 days in accordance with IS 516.

15.1.1 In order to get a relatively quicker idea of the quality of concrete, optional tests on beams for

modulus of rupture at 72 + 2 h or at 7 days, or compressive strength tests at 7 days may be carried

out in addition to 28 days compressive strength test.

For this purpose the values should be arrived at based on actual testing. In all cases, the 28 days

compressive strength specified in Table 2 shall alone be the criterion for acceptance or rejection of

the concrete.

15.2 Frequency of Sampling

15.2.1 Sampling Procedure

A random sampling procedure shall be adopted to ensure that each concrete batch shall have a

reasonable chance of being tested that is, the sampling should be spread over the entire period of

concreting and cover all mixing units.

15.2.2 Frequency

The minimum frequency of sampling of concrete of each grade shall be in accordance with the

following:

Quantity of Concrete in the Number of Samples

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Quantity of Concrete in the work , m 3 No of samples

1-5 1

6-15 2

16-30 3

31-50 4

51 and above 4 plus one additional sample for each additional

50 m 3 or part thereof

NOTE – At least one sample shall be taken from each shift where concrete is produced at

continuous production unit, such as ready-mixed concrete plant, suppliers and purchasers may

agree upon frequency of sampling mutually by suppliers and purchasers.

15.3 Test Specimen

Three test specimens shall be made for each sample

IS 456 : 2000

for testing at 28 days. Additional samples may be required for various purposes such as to determine

the strength of concrete at 7 days or at the time of striking the formwork, or to determine the

duration of curing, or to check the testing error. Additional samples may also be required for testing

samples cured by accelerated methods as described in IS 9103. The specimen shall be tested as

described in IS 516.

15.4 Test Results of Sample

The test results of the sample shall be the average of the strength of three specimens. The

individual variation should not be more than +15 percent of the average. If more, the test results of

the sample are invalid.

Total Quality Management ( TQM )

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Total quality management (TQM) is a system of continuously improving goods or services. The

philosophy was promoted by W. Edwards Deming. A TQM approach is considered as essential to long

term survival of the business, such as construction. In the TQM philosophy, everyone in the

company should feel involved and committed for quality of products, from top to bottom of the

organization. Total quality management provides principles, tools and techniques for cultural changes

and continuous improvement. Quality assurance can be considered as part of Total Quality

Management. Basically quality assurance is a system of approach which is related to attitudes and

working environment of the company. Deming has suggested 14 points for total quality management

which are –

1. create constant commitment to the employee for aim and purpose of the company and

improvement .

2. Adopt new philosophy to avoid defects.

3. Use statistical quality control and understand purpose of inspection.

4. Practice of business should be based on statistical evidence rather than price tag alone.

5. Improve constantly and forever production and services.

6. Employee training.

7. Teach and institute leadership.

8. Encourage communication and productivity.

9. Encourage teamwork, to work in group.

10. Eliminate posters or slogans with specific improvement methods.

1. Use statistical methods to continuously improve quality and productivity.

2. Remove barriers that rob people of pride of workmanship.

3. Provide education and self improvement for everybody.

4. Define top management commitment for quality.

The basic foundation for total quality management is –

Everyone in the company should understand the mission and vision of the business.

Total management should be highly committed to quality.

Continuous training is required.

RECORDS TO BE MAINTAINED AT CONSTRUCTION SITE

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RECORDS TO BE MAINTAINED ATCONSTRUCTION SITE

Records to be maintained at construction sites play

important role in construction activities. It is a

document required to prove any construction activity

has taken place at site during billing or any other

claims.

These records have all the data of various

construction activities carried out at site. If any

additional work has been carried out and it is claimed

during billing, these documents need to be produced

as a proof.

Maintenance of records also helps during audits of

construction projects at any point of time. These documents helps to defend any claims such as

liquidated damages or false claims or violations of any guidelines by authorities or clients.

Records to be Maintained at Construction Site

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RECORDS TO BE MAINTAINED AT CONSTRUCTION SITE

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Following are the various records that need to be maintained at construction site:

1. Contract Agreement:

Contract agreement documents including all sets of drawings, including amendments, a copy of

approval of municipality, corporation or urban development authorities need to be maintained at

construction sites till the completion of construction projects. These documents provides permission

and guidelines for all the activities carried out at the construction site.

2. Time and Progress Charts or CPM Charts:

These charts help in tracking the construction activities from time to time and help in effective

planning, scheduling and controlling the construction projects activities. These charts need to be

approved from the concerned authorities.

3. Work orders book:

All the orders given by clients to the contractors need be maintained with serial numbers, signatures

and dates. These orders should be specific for works. This order should also have a compliance

column.

4. Works Diary:

Works diary of a construction project should indicate contract agreement number, name of work,

amount of contract, date of commencement of work, date of completion and extension time granted.

All the relevant details need be entered daily in the works diary. This diary serves as an authentic

record. Following details need to be entered in this diary with due care:

1. Weather at site

2. Labors employed

3. Important materials brought to site with their approximate quantity

4. Types of transport working at site

5. Types of tools and plants being used at site

6. Important items of works completed and passed on the particular date

7. Visits of VIPs and their remarks if any.

RECORDS TO BE MAINTAINED AT CONSTRUCTION SITE

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5. Works Passing Records:

This record maintains all the activities to be carried out at construction site. It consists of an index

page with details of all items of works to be done under the contract and other pages with details of

progress of each works. This helps in tracking the progress of each activity of construction and helps

in pre-planning for other remaining activities which starts after completion of current activity. This

also helps in acquiring approvals before time for activities to be started.

6. Tests Results Record:

This is also an important record to be maintained at construction site as a proof for construction

quality. This record consists of tests of various materials such as cement, sand, aggregates, water,

steel reinforcement used at construction site, test records of concrete cubes, concrete cylinders,

slump tests etc.

These records are arranged as an index page with details of each materials, page numbers of

records etc. Individual pages consists of each materials, with their test dates, results etc.

All the tests carried out at site or in laboratory are recorded in the this record book. Some of the

tests carried out at construction sites for civil works are:

Cube tests for concrete works for each location or structural members.

Sieve analysis of coarse aggregates, impact or abrasion tests.

Sieve analysis of coarse sand for concrete works, masonry sands for masonry works, plastering

and pointing works etc.

Tests for impurities of aggregates and sands.

Bulking of sand test for concrete and masonry works.

Slump tests and compacting factor tests for concrete works.

Crushing strength test, tolerance, water absorption test, efflorescence tests of bricks, stones or

masonry work.

Moisture contents of timber.

Manufacturer tests reports provided by the vendors for admixtures, reinforcing steels etc.

And any other tests are required by the contract documents.

7. Cement Register:

This record is maintained with details of receipts, daily consumptions and remaining balance at site.

RECORDS TO BE MAINTAINED AT CONSTRUCTION SITE

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This record also consists of manufacturing dates of cement, date of receipt and test reports of

cement at site or manufacturers test reports.

8. Register for approval of Samples:

This record provides details of all the samples for construction materials that has been approved or

rejected by the clients. Approvals from the client is necessary for the construction materials to be

used before commencement of the project. All the samples approved by the clients need to be kept

separately along with their tests reports with approvals of the clients and contractors till the

completion of the work.

9. Records of Changes, Deviation orders and Amendments:

Many a times during the construction projects, there are deviations or changes or amendments to

the contract documents and work activities from time to time during construction project as required

by the clients. These changes can be in a drawing, specifications or additional works.

A record of all such deviation orders and amendments to contract agreement together with their

financial effect should be maintained along with approval or signatures from the clients. If these

changes involves in any extension of time of the contract, these should also be recorded.

10. Measurement Books:

The measurement book is a record for all the construction activities carried out and approved by the

client. These records are important for a contractor to maintain and help during billing claims. Any

extra work done is also recorded in this book with notes.

REINFORCEMENT QUANTITY ESTIMATION

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REINFORCEMENT QUANTITY ESTIMATION

REINFORCEMENT QUANTITY ESTIMATION

For estimating the cost of the structure, it is

necessary for the quantities of the materials,

including those of the reinforcement to be known.

Accurate quantities of the concrete and brickwork can

be calculated from the layout drawings. If working

drawings and schedules for the reinforcement are not

available it is necessary to provide an estimate of the

anticipated quantities. The quantities are normally

described in accordance with the requirements of the

Standard method of measurement of building

works.

In the case of reinforcement quantities the basic requirements are:

1. Bar reinforcement should be described separately by steel type (e.g. mild or high-yield steel),

diameter and weight and divided up according to:

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REINFORCEMENT QUANTITY ESTIMATION

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(a) Element of structure, e.g. foundations, slabs, walls, columns, etc., and

(b) Bar ‘shape’, e.g. straight, bent or hooked; curved; links, stirrups and spacers.

2. Fabric (mesh) reinforcement should be described separately by steel type, fabric type and area,

divided up according to 1(a) and 1(b) above.

Reinforcement Quantity Estimation

There are different methods for estimating the quantities of reinforcement;, three methods of

varying accuracy are:

Method-1 for Reinforcement Estimation

The simplest method is based on the type of structure and the volume of the reinforced concrete

elements. Typical values are, for example:

• Warehouses and similarly loaded and proportioned structures: 1 tonne of reinforcement per 105m

• Offices, shops, hotels: 1 tonne per 13.5m

• Residential, schools: 1 tonne per 15.05m

However, while this method is a useful check on the total estimated quantity it is the least accurate,

and it requires considerable experience to break the tonnage down to Standard Method of

Measurement requirements.

Method-2 for Reinforcement Estimation

Another method is to use factors that convert the steel areas obtained from the initial design

calculations to weights, e.g. kg/M or kg/m as appropriate to the element.

If the weights are divided into practical bar diameters and shapes, this method give a reasonably

accurate assessment. The factors, however, do assume a degree of standardization both of structural

form and detailing.

This method is likely to be the most flexible and relatively precise in practice, as it is based on

reinforcement requirements indicated by the initial design calculations.

3

3

3

2

REINFORCEMENT QUANTITY ESTIMATION

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Method-3 for Reinforcement Estimation:

For this method sketches are made for the ‘typical’ cases of elements and then weighted.

This method has the advantages that:

(a) The sketches are representative of the actual structure

(b) The sketches include the intended form of detailing and distribution of main and secondary

reinforcement

(c) An allowance of additional steel for variations and holes may be made by inspection.

This method can also be used to calibrate or check the factors described in method 2 as it takes

account of individual detailing methods.

When preparing the reinforcement estimate, the following items should be considered:

(a) Laps and starter bars

A reasonable allowance for normal laps in both main and distribution bars and for starter bars has

shall be considered. It should however be checked if special lapping arrangements are used.

(b) Architectural features

The drawings should be looked at and sufficient allowance made for the reinforcement required for

such ‘non-structural’ features.

(c) Contingency

A contingency of between 10% and 15% should be added to cater for some changes and for possible

omissions.

REPAIR OF POST CONCRETING DEFECTS IN STRUCTURES

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REPAIR OF POST CONCRETING DEFECTS INSTRUCTURES

The four essential features of a successful repair are:

1. Expediency: The longer the repair is left, the

more work has to be done, and the less likely that

the repair will blend in.

2. Cleanliness: when repairing concrete, care must

be taken to remove any dirt or dust that will prevent

the repair concrete bonding with the parent concrete.

3. Correct technique: The correct technique and the correct tools are essential for repairing

damaged concrete.

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REPAIR OF POST CONCRETING DEFECTS IN STRUCTURES

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4. The repair material must be durable as the parent concrete.

The repairs should be done while the concrete is still very young, so that the repairs are much the

same as the parent concrete. All areas to be repaired should be free from loose dirt or dust so that

no attempt is being made to bond the repair of particles of dust.

Individuals assigned to complete repairs should know what action is required, i.e. they should have

been trained in the appropriate tasks, because repairing concrete requires greater skill than placing

concrete first time around.

Materials for Repairing Post Concrete Defects:

Before commencing the repair, the operative must have all the necessary materials and equipment.

The materials normally used for patch repairs are:

Portland cement and white Portland cement: Repairs are tend to be made with a high

concentration of cement which will make the finished repair appear darker than the parent concrete.

White Portland cement helps to lighten the colour.

Aggregate and sand: Preferably the same as used in the original mix, together with limestone fines

(which also helps to lighten the colour).

Gauging liquid: this is generally water with a polymeric material such as styrene butadiene rubber

(SBR), polyvinyl acetate (PVA) or an acrylic material. These improve the cohesion and adhesion of

the repair to the parent concrete, and also give better physical properties to the hardened concrete,

such as imperviousness and elasticity.

When repairing cracks the above materials can be used but sometimes an epoxy or polyester resin

will sometimes be required, depending on the width of the crack.

Equipment for repairs of concrete:

The below fig. shows the general equipments required for concrete repairs.

REPAIR OF POST CONCRETING DEFECTS IN STRUCTURES

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If the repair is extensive, then the formwork, formwork ties or clamps and string-backs may be

needed. All repairs should be cured, so plastic sheeting and tape to adhere it to the concrete should

be available.

Repairing of Honeycombed Concrete:

The technique used in repairing honeycombed concrete are common to other defects and involve

replacing mortar loss close to the surface. The step by step process of repairing honeycombed

concrete is as follows:

1. Using the hammer and chisel remove the honeycombed concrete and so on until it has all be

removed.

2. The area should then be brushed out to remove any dust.

3. Now prepare the replacement concrete. A rule of thumb for this is to use a 1:2 combination of

cement and limestone fines with the cement comprising of an equal mixture of Portland and white

cement. Gauging liquid can contain equal amounts of water and polymer, although on low maturity

repairs water on its own should suffice.

4. Gauging liquid should be added such that the mixture is just moist. A low slump mix specially

necessary on a vertical surface so that it does not slump out of position.

5. The replacement concrete is then placed into the cavity using a trowel.

6. In a repair this small, the use of vibrator is impractical, so a rod is used to compact the concrete,

which is then smoothed again using the trowel.

7. The concrete repair is then cured by placing some plastic sheeting over it and securing it with

adhesive tape.

Structural repairs post concreting:

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If the honeycombing is deep or as occasionally happens, passes through a section, the concrete will

need to be removed and the whole section recast. Before starting this exercise the column or section

above the repair area will need supporting by an appropriate form of propping. The defective area

can then be broken out. This will usually need more than a hammer and chisel, such as Pneumatic

hammer as shown in figure below.

With the honeycombed concrete removed and the area removed of dust, the formwork can be

erected. The formwork will need a special hole cut into it (sometimes called a letterbox or birds

mouth) so that the concrete can be placed whilst the formwork is in place.

The concrete mix for the repair can be the same as the mix used in the original pour. The concrete

can be placed through the opening and vibrated using a small vibrating poker. The repair may also

need some external vibration as well. Care must be taken when placing the last of the concrete as to

ensure that all the void is filled.

The formwork should be left in place for 24 hours and then removed.

Repair of blow holes in concrete structure:

A technique called “Bagging in: is used to repair excessive blow holes in the surface of concrete. This

technique involves using a hessian pad to rub a cement paste into the holes. No other vibration or

compaction is required.

The repair mix is normally made from a 1:4 mix of cement and fine grade sand (silver sand is often

used) with sufficient water to make a very stiff paste, so that it holds together when squeezed, but

no water escapes.

The treatment is most effective if done as soon as the formwork is struck, preferably the day after

casting. A carborundum stone should be used to scour the surface and to expose any other blow

holes close to the surface. The grinding of the surface will also expose more unhydrated cement

particles that can bond with the repair work.

REPAIR OF POST CONCRETING DEFECTS IN STRUCTURES

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TAGS Concrete Technology Repairing Structual Inspection Structure Repair Guide

A hessian pad is filled with the mix and rubbed over the concrete surface in an overlapping circular

motion, filling the holes and coating the surface with a fine cement paste.

Repair of cracks in post concrete structures:

Cracks should always be reported to the relevant supervising authority. A small degree of cracking is

quite common in most concrete structures, and can sometimes be ignored depending on how

prevalent they are. Of course cracks can also indicate that there is something wrong.

Since the main function of concrete in the cover zone is to protect the steel reinforcement from

corrosion, cracks in floor slabs can generally be filled with a cement paste. This is particularly

satisfactory if the slab is to have a surface topping, which will hide the crack and provide extra

protection. Cracks in walls or other places where this method can not be used, need to be repaired

by other means.

Firstly the cracks must be analysed and determined if they are live or not. A live crack indicates that

it is likely to grow over time, and a flexible joint needs to be formed. Dead cracks can be injected

with a resin.

REQUIREMENTS OF UNDERGROUND (BASEMENT) WALLS

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REQUIREMENTS OF UNDERGROUND(BASEMENT) WALLS

Underground or basement walls are required to be

constructed in case of underground water tank,

basement parking, as a store room and many other

purposes. These underground or basement walls are

exposed to many types of loads and forces, moisture

due to presence of ground water or due to rains etc.

Underground walls must support following

functional requirements whether it is in a framed

structure or load bearing structure:

Structural Stability

Durability

Moisture exclusion

Buildability

The presence of salts, high water table interfere with the construction process of the building, and it

also affects the durability. These problems create restrictions on the nature of construction of walls

below ground level and it is particularly important in case of basement to be used as internal building

space.

Underground or Basement Wall Requirement

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REQUIREMENTS OF UNDERGROUND (BASEMENT) WALLS

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TAGS Buildings Underground Walls Walls

Due to moisture conditions in case of high water table, materials with low porosity are to be used.

Porous materials absorb moisture from the ground and expand on freezing, causing spalling and

friability of the material. Non-porous materials also tend to perform better in terms of moisture

exclusion, since they do not transfer moisture through capillarity.

The underground walls are subjected to high pressures, both axially and laterally. The lateral force

exerted by the mass of earth which surrounds the walls can have a considerable effect, particularly

in the case of walls to deep basements. These lateral loads must be adequately resisted if the

stability of the wall is to be maintained. This is generally done either by bracing the walls or by

constructing walls that are sufficiently robust to cope with the stresses involved.

To resist this loading, bracing walls below ground level with temporary supports or to utilise the

floors of the buildings as permanent braces. Also, walls can be constructed to minimise the ground

pressure by bracing them gradually as the work proceeds.

RESIDENTIAL BUILDING SITE PLANNING

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RESIDENTIAL BUILDING SITE PLANNING

Selection of site for

any building is a very important and experts job and

should be done very very carefully by an experienced

engineer. The requirements of site for buildings with

different occupancies are different. So all the

buildings proposed for different purposes have

different requirements and thus different

considerations for their site selection.

Site Selection for Residential Buildings

Following are some of the important factors which should be considered while selecting site for any

residence.

1. The site should be in fully developed area or in the area which has potential of development.

2. The site should command a good view of landscape such a hill, river, lake, etc.

3. There should be good transport facilities such as railway, bus service, for going to office, college,

market, etc.

4. Civic services such as water supply, drainage sewers, electric lines, telephone lines, etc. should be

very near to the selected site so as to obtain their services with no extra cost.

5. Soil at site should not be of made up type as far as possible. The buildings constructed over such

soils normally undergo differential settlement and sometimes become the cause of collapse.

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TAGS Building Site Selection Construction Site Selection Residential Building Residential site plan Site Selection

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Cracks in buildings in such conditions, are quite common

6. The selected site should be large enough; both to ensure the building abundant light and air to

prevent any over dominance by the neighbouring buildings.

7. The ground water table at the site should not be very high.

8. Nearness of schools, hospitals, market, etc. are considered good for residential site but these

facilities do not carry any significance in the selection site for other public buildings.

9. Good foundation soil should be available at responsible depth. This aspect saves quite a bit in the

cost of the building.

10. Residential house site should be located away from the busy commercial roads.

11. Residential site should not be located near workshops, factories, because such locations are

subjected to continuous noise.

12. Orientation of the site also has some bearing on its selection. Site should be such in our country

that early morning sun and late evening sun is accepted in the building in summer and maximum

sun light is available in most of winter.

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ROLE OF A PROJECT MANAGER

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Home Construction

project manager

ROLE OF A PROJECT MANAGER

Role of Project Manager

The responsibility

of project manager to make sure that the customer is

satisfied and the work scope is completed in a quality

manner, using budget, and on time. The Project

Manager has primary responsibility for providing

leadership in planning, organizing and controlling the

work effort to accomplish the project objectives. In

other words, the project manager provides the

leadership to project team to accomplish the project

objective. The project manager coordinates the activities of various team members to ensure that

they perform the right tasks at the proper time, as a cohesive group. The different roles of project

manager are as follows:

Planning

Organizing

Controlling

Leading

Communicating

Cognitive functions

Self management functions

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ROLE OF A PROJECT MANAGER

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Motivational and personal development functions

Customer awareness functions

Organizational savvy functions

Planning

First, the project manager clearly defines the project objectives and reaches agreement with the

customer on this objective. The manager then communicate this objective to the project team in

such a manner as to create a vision of what will constitute successful accomplishment of the

objective. The project manager spearheads development of a plan to achieve the project objectives.

By involving the project team in developing this plan, the project manager ensures more

comprehensive plan than he or she could develop alone. Furthermore, such participation gains the

commitment of the team to achieve the plan. The project manager reviews the plan with the

customer to gain endorsement and then sets up the project management information system-either

manual or computerized-for comparing actual progress to plan progress. It’s important that this

system be explained to the project team so that the team can use it properly to manage the project.

Organizing

Organizing involves securing the appropriate resources to perform the work. First, the project must

decide which tasks should be done in-house and which tasks should be done by subcontractors or

consultants. For tasks that will be carried out in-house, the project manager gains a commitment

from the specific people who will work on the project. For tasks that will be performed by

subcontractors, the project manager clearly defines the work scope and deliverables and negotiates

a contract with each subcontractor. The project manager also assigns responsibility and delegates’

authority to specific individuals or subcontractors for the various tasks, with the understanding that

they will be accountable for the accomplishment of their tasks within the assigned budget and

schedule. For large projects involving many individuals, the project manager may designate leaders

for specific group of tasks. Finally, and most important, the task of organizing involves creating an

environment in which the individuals are highly motivated to work together as a project team.

Controlling

To control the project, the project manager implements a management information system designed

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to track actual progress and compare it with planned progress. Such a system helps the manager

distinguish between busy-ness and accomplishments. Project team members monitor the progress of

their assigned tasks and regularly provide data on progress, schedule and cost. These data are

supplemented by regular project review meetings. If actual progress falls behind planned progress or

unexpected events occur the project manager takes immediate action. He or she obtains input and

advice from team members regarding appropriate corrective actions and how to replan those parts

of the project. It’s important that problems and even potential problems, be identified early and

action taken. The project manager cannot take a “let’s wait and see how things works out” approach-

things never works out on their own. He or she must intervene and be proactive, resolving problems

before they become worse.

Leading

Project manager fosters development of a common mission and vision to the team members. He

should clearly define roles, responsibilities and performance expectations for all his team members.

He uses leadership style appropriately to situation or stage of team development. He should be able

to foster collaboration among team members. He should provide clear direction and priorities to his

team members. He should be efficient enough to remove obstacles that hamper team progress,

readiness or effectiveness. He should promote team participation in problem solving and decision

making as appropriate. He should pass credit on to team, and promotes their positive visibility to

upper management. He should appreciate, promote and leverage the diversity within the team.

Communicating

The Project Manager should be able to communicate effectively with all levels inside and outside of

the organizations. He should be able to negotiate fairly and effectively with the

customers/subcontractors. He should be able to bring conflicts into the open and manages it

collaboratively and productively with the help of other team members. He should be able to able to

influence without relying on coercive power or threats. He should be able to convey ideas and

information clearly and concisely, both in writing and orally to all the team members.

Cognitive functions

The project manager should identify the problem and gathers information systematically and seeks

input from several sources. He should then consider a broad range of issues or factors while solving

these problems. For this he collects the appropriate quantity of data for the situation and discusses it

with all the team members before making a decision. He then draws accurate conclusions from

quantitative data and makes decisions in an unbiased, objective manner using an appropriate

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process. For this process of decision making he understands the concept of risk versus return and

makes decision accordingly.

Self management functions

The project manager should be able to maintain focus and control when faced with ambiguity and

uncertainty and should be able to show consistency among principles, values and behavior. He

should be resilient and tenacious in the face of pressure, opposition, constraints, or adversity. Being

the head of the project he should manage implementations effectively and should recognize as

someone “who gets things done.” He should continuously seek feedbacks from the team members

and modify his behavior accordingly. He should take keen interest in learning and self development

opportunities.

Motivational and personal development functions

Project manager should consider individual skills, values and interest of all his team members when

assigning or delegating tasks to them. He should allow team members an appropriate amount of

freedom to do the job. He should accurately access individual strength and development needs of his

team members to complete the work effectively. He should continuously offer opportunities for

personal and professional growth to his team members. He should arrange for training program and

continuously seeks support to his team member when needed. He should pass credit on to the

individuals and promote their positive visibility to upper management. He should give timely, specific

and constructive feedback to all his team members.

Customer awareness functions

Project manager should be able to anticipate customer’s needs effectively and proactively strives to

satisfy them. He should be able to accurately translate the customer’s verbalized wants into what

they actually needs. He should be able to understand customers and their business and actively build

and maintain strong customer relationships. He should understand customer’s issues, concerns and

queries and try to resolve them effectively. He should actively strive to exceed customer

expectations.

Organizational savvy functions

Project manager should involve the right people at the right time for a particular job. Understands,

accepts and properly uses power and influence in relationships. He should build and leverage formal

and informal networks to get things done. He should know the mission, structure and functions of

the organizations and others. He should understand profitability and general management

ROLE OF CONSTRUCTION SITE ENGINEER

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Role of Site Engineer

ROLE OF CONSTRUCTION SITE ENGINEER

Role of Construction Site Engineer depends on the

type of work involved and experience of site engineer

in a construction project. The duties and

responsibilities of a construction site engineer are

typically as follows, many of these will be delegated

to other engineers on the site according to their

experience and ability:

Setting out the

works in

accordance with the drawings and specification

Liaising with the project planning engineer

regarding construction programmes

Checking materials and work in progress for compliance with the specified requirements

Observance of safety requirements

Resolving technical issues with employer’s representatives, suppliers, subcontractors and

statutory authorities

Quality control in accordance with CSIs/procedures method statements, quality plans and

inspection and test plans, all prepared by the project management team and by subcontractors

Liaising with company or project purchasing department to ensure that purchase orders

adequately define the specified requirements

Supervising and counselling junior or trainee engineers

Measurement and valuation (in collaboration with the project quantity surveyor where

appropriate)

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SAFE DESIGN AND CONSTRUCTION OF MULTISTOREY RCC BUILDINGS

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SAFE DESIGN AND CONSTRUCTION OFMULTISTOREY RCC BUILDINGS

MULTISTOREY REINFORCED CONCRETE

BUILDINGS DESIGN

A large number of reinforced concrete multistoreyed

frame buildings were heavily damaged and many of

them collapsed completely in Bhuj earthquake of

2001 in the towns of Kachchh District (viz., Bhuj,

Bhachao, Anjar, Gandhidham and Rapar) and other

district towns including Surat and Ahmedabad. In

Ahmedabad alone situated at more than 250

kilometers away from the Epicentre of the

earthquake, 69 buildings collapsed killing about 700

persons. Earlier, in the earthquake at Kobe (Japan

1995) large number of multistoreyed RC frame buildings of pre 1981 code based design were

severely damaged due to various deficiencies. Such behaviour is normally unexpected of RC frame

buildings in MSK Intensity VIII and VII areas as happened in Kachchh earthquake of January 26,

2001. The aim of this paper is to bring out the main contributing factors which lead to poor

performance during the earthquake and to make recommendations which should be taken into

account in designing the multistoreyed reinforced concrete buildings so as to achieve their adequate

safe behaviour under future earthquakes. The Indian Standard Code IS:1893 was suitably updated in

2002 so as to address the various design issues brought out in the earthquake behaviour of the RC

Buildings. The paper highlights the main provisions of this code.

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multi-storey-buildings

Causes of the Collapse of RC Frame Buildings and Recommendations

Ignorance of the Architects and Structural Engineers about the Contents of the relevant

earthquake resistant Building Codes :

Recommendation:-

The following BIS Standards will be mainly required for the design of RCC Buildings. Architect’s and

Structural engineer’s design office should have the current copies of these standards available in

their offices and all their staff should fully familiarize with the contents of these codes:-

1. IS: 456 -2000 “Code of Practice for Plain and Reinforced Concrete”

2. IS: 875 Part 1 “Unit weights of materials”.

3. IS: 875-1987Design loads ( other than earthquake ) for buildings and structures, Part2

Imposed Loads

4. IS: 875-1987Design loads ( other than earthquake ) for buildings and structures ,Part 3 Wind

Loads

5. IS: 1904-1987 “Code of Practice for Structural Safety of Buildings: Foundation”

6. IS: 1498-1970 Classification and identification of soils for general engineering purposes

(First Revision)

7. IS: 2131-1981 Method of Standard Penetration Test for soils (First Revision)

8. IS: 1905-1987, Code of Practice for Structural Safety of Buildings: Masonry

9. IS:1893(Part-I)-2002 "Criteria for Earthquake Resistant Design of Structures (Fifth

Revision)”.

10. IS:13920-1993, "Ductile Detailing of Reinforced Concrete Structures subjected to Seismic

Forces – Code of Practice"

11. IS: 4326-1993, "Earthquake Resistant Design and Construction of Buildings – Code of

Practice (Second Revision)"

12. IS-NBC-2005: National Building Code of India.

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SEALING MATERIALS FOR JOINTS IN CONCRETE

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SEALING MATERIALS FOR JOINTS IN CONCRETE

There are three types of joints in concrete

construction, viz. construction joint, expansion joint

and contraction joints. Learn more about Joints in

Concrete Structures.

Materials for joints in water retainingstructures and water tight structures

(1) Materials for joints in water retaining structures

and water tight structures for sewage and effluent

treatment shall be resistant to aerobic and anaerobic

microbiological attack and resistant to attack by petrol, diesel oil, dilute acids and alkalis.

(2) Materials for joints in water retaining structures for potable and fresh water shall comply with the

requirements of BS 6920.

Joint filler

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SEALING MATERIALS FOR JOINTS IN CONCRETE

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Joint filler shall be firm, compressible, single-thickness, non-rotting filler. Joint filler for joints in

water retaining structures and watertight structures shall be non-absorbent.

Bitumen emulsion

Bitumen emulsion for joints in water retaining structures and watertight structures shall comply with

BS 3416. Bitumen emulsion for surfaces against which potable or fresh water will be stored or

conveyed shall comply with BS 3416, type II.

joints-in-concrete-structures

Fig: Joints in concrete structures

Joint sealant

(1) Joint sealant shall be a grade suited to the climatic conditions of Hong Kong and shall perform

effectively over a temperature range of 0°C to 60°C. Joint sealant for exposed joints shall be grey.

(2) Joint sealant other than cold-applied bitumen rubber sealant shall be:

(a) A gun grade for horizontal joints 15 mm wide or less and for vertical and inclined joints,

(b) A pouring grade for horizontal joints wider than 15 mm.

(3) Polysulphide-based sealant shall be a cold-applied two-part sealant complying with BS 4254.

Polysulphide-based sealant for expansion joints in water retaining structures and watertight

structures shall have a transverse butt-joint movement range of at least 20%.

(4) Polyurethane-based sealant shall be a cold-applied two-part sealant complying with the

performance requirements of BS 4254.

(5) Hot-applied bitumen rubber sealant shall comply with BS 2499, type N1.

SEALING MATERIALS FOR JOINTS IN CONCRETE

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(6) Cold-applied bitumen rubber sealant shall be of a proprietary type.

(7) Joint sealant for joints in water retaining structures and water tight structures shall be as stated

in Table-1.

(8) Primers and caulking material for use with joint sealant shall be of a proprietary type

recommended by the joint sealant manufacturer.

(9) Different types of joint sealant and primers that will be in contact shall be compatible.

Table-1: Joint sealant for water retaining structures and water tight structures

Structure forretaining / excluding Type of joint Type of joint sealant

Sewage All joints Polyurethane based

Other than sewage

Expansion joint Polyurethane based or Polysulphide based

Horizontal joints other thanexpansion joints

Hot applied bitumen rubber, Polysulphidebased or polyurethane based

Vertical and inclined jointsother than expansion joints

Polysulphide based, polyurethane based orcold-applied bitumen rubber

Bond breaker tape

Bond breaker tape shall be of a proprietary type recommended by the joint sealant manufacturer and

approved by the Engineer. The tape shall be a polyethylene film with adhesive applied on one side

and shall be the full width of the groove.

Bearing strip for sliding joints

Bearing strip for sliding joints shall consist of two plastic strips of a proprietary type approved by the

Engineer. The strips shall be resistant to all weather conditions and to chemicals to which the

structure will be subjected without impairing the reaction, durability or function of the strips.

The strips shall be of a type that will not require maintenance after installation. The strips shall be

capable of withstanding a vertical load of at least 300 kN/m and shall have a maximum coefficient

of friction of 0.3 under a constant shearing force.

Waterstops or water stoppers

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SEALING MATERIALS FOR JOINTS IN CONCRETE

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Waterstops, including intersections, reducers and junctions, shall be of a proprietary type approved

by the Engineer. Waterstops shall be natural or synthetic rubber or extruded polyvinyl chloride and

shall have the properties stated in Table-2.

Table-2: Properties of waterstops or waterstoppers

Property of water stops Rubber waterstops PVC waterstops

Density 1100 kg/m (+/-5%) 1300 kg/m (+/-5%)

Hardness 60 – 70 IRHD 70 – 90 IRHD

Tensile strength >/= 20 N/mm >/= 13 N/mm

Elongation at break point >450% >285%

Water absorption <5% by mass after 48 hoursimmersion

<0.15% after 24 hoursimmersion

Softness number – 42 – 52

While principles of concrete joints remains same, references may also be made to ACI 224.3R-95

Joints in Concrete Construction and IS:3414 – 1968 – Indian Standard Code of Practice for Design

and Installation of Joints in Buildings (Reaffirmed in 2010).

Read More:

1. Joints in Concrete Construction

2. Joints in Liquid Retaining Structures

3 3

2 2

SELECTION OF MORTAR FOR VARIOUS WORKS

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SELECTION OF MORTAR FOR VARIOUS WORKS

Selection of Mortar for Various Works

Different grade of mortar is required for different

nature of work. Special types of mortars are required

under special conditions.

cement mortar

Following table shows the types of mortars required

for various works:

Sl. No.

Nature of work Type of mortar

1. Construction work inwaterlogged areas and exposedpositions

Cement or lime mortar ofproportions 1:3, lime beingeminently hydraulic lime.

2. Damp proof courses andcement concrete roads

Cement mortar proportions 1:2

3. General RCC work such aslintels, pillars, slabs, stairs etc.

Cement mortar of proportions1:3, the concrete mix being1:2:4

4. Internal walls and surfaces of Lime cinder mortar in proportion

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SELECTION OF MORTAR FOR VARIOUS WORKS

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TAGS Building Materials Buildings Mortar

less importance 1:3, sand is replaced by ashes orcinder.

5. Mortar for laying fire-bricks Fire-resistant mortar consistingof 1 part of aluminous cement to2 parts of finely crushed powderof fire-bricks.

6. Partition walls and parapet walls Cement mortar of proportions1:3 or lime mortar of 1:1. Limeshould be moderately hydrauliclime.

7. Plaster work Cement mortar of proportion 1:3to 1:4 or lime mortar proportion1:2

8. Pointing work Cement mortar of proportion 1:1to 1:2

9. Reinforced brickwork Cement mortar proportion 1:3

10. Stone masonry with bestvarieties of stones

Lime mortar proportions 1:2,lime being eminently hydrauliclime.

11. Stone masonry with ordinarystones, brickwork, foundations,etc.

Lime mortar of 1:2 or cementmortar of 1:6, lime should beeminently hydraulic lime ormoderately hydraulic lime.

12. Thin joints in brickwork Lime mortar of 1:3, lime beingfat lime.

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SETTING OUT A BUILDING PLAN ON GROUND

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SETTING OUT A BUILDING PLAN ON GROUND

A building is set out in order to clearly define the

outline of the excavation and the centre line of the

walls, so that construction can be carried out exactly

according to the plan. The centre line method of

setting out is generally preferred and adopted.

PROCEDURE

SETTING OUT A BUILDING PLAN ON GROUND

Fig.1: Example plan to be set out on the ground

1. From the plan (fig 1), the centre line of the walls are calculated. Then the centre lines of the

rooms are set out by setting perpendiculars in the ratio 3:4:5. Suppose the corner points are a, b, c,

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d, e, f and g which are marked by pegs with nails on top.

2. The setting of the corner point is checked according to diagonals ac, bd, cf and eg.

3. During excavation, the centre points a, b, c, d, e, f, g may be removed. Therefore the centre lines

are extended and the centre points are marked about 2m away from the outer edge of excavation.

Thus the points A1, A2, B1, B2 and like wise, are marked outside the trench. Centre line are shown

clearly by stretching thread or rope. The centre points fixed 2m away from the excavation are

marked with sit out pegs.

4. From the plan details, the width of excavation to be done is also marked by thread with pegs at

appropriate positions.

5. The excavation width is then marked by lime or by with furrow with spade.

6. If the plan is much to complicated and follows a zigzag pattern, then the centre pegs are kept at

suitable positions according to site conditions.

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Shoring, Underpinning and Scaffolding

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Shoring, Underpinning and Scaffolding

Shoring is a general term

used in construction to

describe the process of

supporting a structure in

order to prevent collapse so

that construction can

proceed. The phrase can also

be used as a noun to refer to the materials used in

the process.

Underpinning is the process of strengthening and

stabilizing the foundation of an existing building or

other structure.

Scaffolding is a temporary frame used to support

people and material in the construction or repair of buildings and other large structures.

Shoring is used to support the beams and floors in a building while a column or wall is removed. In

this situation vertical supports are used as a temporary replacement for the building columns or

walls.

Trenches – During excavation, shoring systems provide safety for workers in a trench and speed

excavation. In this case, shoring should not be confused with shielding. Shoring is designed to

prevent collapse where shielding is only designed to protect workers when collapses occur. concrete

structures shoring, in this case also referred to as falsework, provides temporary support until the

concrete becomes hard and achieves the desired strength to support loads.

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Shoring Techniques

Raking Shore

Raking Shores consist of one or more timbers sloping between the face of the structure to be

supported and the ground. The most effective support is given if the raker meets the wall at an

angle of 60 to 70 degrees. A wall-plate is typically used to increase the area of support.

Hydraulic Shoring

Hydraulic shoring is the use of hydraulic pistons that can be pumped outward until they press up

against the trench walls. They are typically combined with steel plate or plywood, either being 1-

1/8″ thick plywood, or special heavy Finland Form (FINFORM) 7/8″ thick.

Beam and Plate

Beam and Plate steel I-beams are driven into the ground and steel plates are slid in amongst them.

A similar method that uses wood planks is called soldier boarding. Hydraulics tend to be faster and

easier; the other methods tend to be used for longer term applications or larger excavations.

Soil Nailing

Soil nailing is a technique in which soil slopes, excavations or retaining walls are reinforced by the

insertion of relatively slender elements – normally steel reinforcing bars. The bars are usually

installed into a pre-drilled hole and then grouted into place or drilled and grouted simultaneously.

They are usually installed untensioned at a slight downward inclination. A rigid or flexible facing

(often sprayed concrete) or isolated soil nail heads may be used at the surface.

Continuous Flight Augering

Continuous Flight Augering (CFA) is a method used to create concrete piles to support soil so that

excavation can take place nearby. A Continuous Flight Augering drill is used to excavate a hole and

concrete is injected through a hollow shaft under pressure as the auger is extracted. This creates a

continuous pile without ever leaving an open hole.

Underpinning

Underpinning may be necessary for a variety of reasons:

Shoring, Underpinning and Scaffolding

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TAGS Downloads Failures of Structures

* The original foundation is simply not strong or stable enough, e.g. due to decay of wooden piles

under the foundation.

* The usage of the structure has changed.

* The properties of the soil supporting the foundation may have changed (possibly through

subsidence) or were mischaracterized during planning.

* The construction of nearby structures necessitates the excavation of soil supporting existing

foundations.

* It is more economical, due to land price or otherwise, to work on the present structure’s foundation

than to build a new one.

Underpinning is accomplished by extending the foundation in depth or in breadth so it either rests on

a stronger soil stratum or distributes its load across a greater area. Use of micropiles and jet grouting

are common methods in underpinning. An alternative to underpinning is the strengthening of the soil

by the introduction of a grout. All of these processes are generally expensive and elaborate.

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SPECIFICATION FOR MARBLE MOSAIC TILE FLOORING

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Home Building Technology

SPECIFICATION FOR MARBLE MOSAIC TILEFLOORING

The laying and finishing of cement concrete marble

mosaic flooring tiles in floors, wall, staircases, etc. is

discussed here.

Materials required for mosaic tile flooring:

Cement, sand, terrazzo tiles shall conform to the

specifications detailed in the relevant standard code.

Mixing of mortar is done as per the specification for

grade of mortar to be used.

Laying of mosaic tile flooring:

Subgrade concrete or the RCC slab on which tiles are to be laid is cleaned, wetted and mopped. The

bedding of the tiles generally used is cement mortar 1:5 or as specified. The average thickness of

mortar used is 30mm and thickness at any place not less than 10mm. Lime mortar bedding is

spread, tamped and corrected to proper levels and allowed to harden for a day before the tiles are

laid. Over this bedding, neat grey cement slurry of honey like consistency is spread at the rate of 4.4

kg/sq.mt over such an area that would accommodate 20 tiles.

Before laying, the tiles are soaked in water for at least 20 minutes and then allowed to dry for about

10 minutes. It is necessary to have tiles damp but not wet when they are laid. Tiles should be fixed

by gently

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SPECIFICATION FOR MARBLE MOSAIC TILE FLOORING

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tapping with a wooden mallet till they are properly bedded and in level with the adjoining tile. The

joints is kept as thin as possible not exceeding 1.5 mm. Where full-size tiles cannot be fixed, tiles are

cut to the required size and their edges rubbed to ensure a straight and true joint. Tiles which are

fixed in the floor adjoining the wall should enter not less than 12mm under the plaster, skirting or

dado. After the tiles have been laid, excess cement coming out through the joints upto the surface is

immediately wiped clean.

mosaic-tile-flooring

Curing, Polishing and finishing of mosaic tiles:

The day after the tiles are laid all joints are cleaned of the grey cement with a wire brush. The joints

shall after 24 hours be filled with matching cement paste and allowed to set. The same cement slurry

is applied to the entire surface of the tiles in a thin coat with a view to protect the surface from

abrasive damage and fill the pin holes that may exist on the surface.

The floor is then kept wet and protected for a minimum period of seven days before starting the

polishing. No one should be allowed to walk on the floor during the first 24 hours immediately after

the tiles are laid.

The surface thereafter is grounded evenly with machine fitted coarse grade grit block. Water is used

profusely during grinding. It is then covered with a thin coat of cement mixed with colouring pigment

to match the topping of the wearing surface of the tile sand second grinding is then carried out with

machine fitted with fine grade grit blocks. The final grinding with machine fitted with the finest grade

grit blocks is carried out after 24 hours of completion of second grinding or before handing over the

floor. The entire surface is finally washed with weak solution of soft soap in warm water.

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STRENGTHENING OF MASONRY WALLS

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Home Building Technology Brick Masonry

STRENGTHENING OF MASONRY WALLS

Strengthening of masonry walls is required to

prevent failure and collapse during major earthquake

or addition of extra load on buildings. Strengthening

of masonry walls also may be required during

rehabilitation of buildings.

Unreinforced masonry walls have good compressive

strength, but they are brittle and very weak under

the action of lateral loads which causes tension in

walls. Whenever tension forces acts on a masonry

wall, it tends to crack.

Cracking of masonry walls may occur due to

settlement of foundation, during earthquakes, application of lateral loads. There can be several

causes for masonry wall cracks, but occurrence these cracks may lead to complete collapse of wall.

Some of the failures of masonry walls are shown in images below:

Out-of-plane failure of masonry walls

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STRENGTHENING OF MASONRY WALLS

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Fig: Out-of-plane failure of masonry walls

Fig: Corner Failure of Masonry Walls

Fig: Vertical Cracks in Masonry Walls

Fig: Roof Collapse due to Removal of Wall

In a load bearing masonry buildings, loads from the building is transferred through walls and failure

and collapse of such masonry walls can lead to complete collapse of the building.

In case of reinforced concrete framed structures, although loads are transferred through columns,

but in the event of an earthquake, these walls are more susceptible to develop cracks and fail.

Uses of half brick thick masonry walls are common as partitions in the interior of RC framed

buildings. These half brick masonry walls are unsafe under the action of lateral forces during

earthquake. Out of plane strengthening of partitions can be clubbed together with lateral

strengthening of building by providing reinforced concrete jackets to the partitions.

To prevent the collapse of masonry walls during earthquake, it is advisable to use reinforced brick

masonry walls in new construction. Existing masonry walls can also be strengthened by providing

reinforced concrete jackets on one or both sides of the walls.

Methods of Masonry Wall Strengthening:

Masonry walls can be strengthened by following methods:

STRENGTHENING OF MASONRY WALLS

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1. Providing reinforced concrete jackets on one or both faces of walls.

2. Use of FRP Structural Repointing for strengthening of masonry walls (Source: Strengthening of

Masonry Walls by FRP Structural Repointing by Gustavo Tumialan, Pei-Chang Huang, Antonio Nanni,

Pedro Silva)

Masonry wall Strengthening using RC Jackets:

Reinforced concrete (RC) jackets technique for strengthening of masonry structure consists of

application of jackets on one or both sides of masonry walls. This method is used for brick masonry

as well as for stone masonry walls.

For using reinforcement jackets, first the plaster is removed from the walls. Mortar joints between

bricks are cleaned. In case of any cracks in masonry walls, those are first grouted. Anchor ties are

are inserted in pre-drilled holes. The surface of drill is cleaned, moistened, and cement slurry is

spread on the masonry surface and in drills.

The concrete is applied in two-layers with reinforcement mesh in between them. The reinforcing

mesh on both sides of wall is connected with the help of steel anchors. These anchors are welded

with the mesh or tied using tying wire.

The usual total thickness of RC jackets varies from 30mm to 100mm. The thickness depends on the

method for application of concrete layers.

Rules for Strengthening of Masonry Walls by Reinforced Concrete Jacketing:

The minimum horizontal and vertical reinforcement should be 0.25% of the jacket section.

The minimum reinforcement with which the ends of the wall are strengthened should be 0.25% of

jacket section.

The diameter of the ties at the well ends should not be less than 8 mm with a maximum spacing

of 150 mm.

The jacket must be anchored to the old concrete with dowels spaced at no more than 600 mm in

both directions.

STRENGTHENING OF MASONRY WALLS

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Fig: Strengthening of Masonry Walls by Application of Single and Double sided reinforced

concrete (RC) jackets (source: Paper by S. Churilov & E. Dumova-Jovanoska on “Analysis of

masonry walls strengthened with RC jackets”

It is also important that the jacket should be able to transfer forces to slab diaphragms. This can be

achieved by providing epoxy grouted anchors and diagonal connecting bars through holes made in

slabs.

Strengthening of Masonry Walls by Using FRP StructuralRepointing:

Structural repointing of masonry walls has advantages compared to the use of FRP laminates. This

method of masonry wall strengthening is simple since the surface preparation is reduced

(sandblasting and puttying) is not required. In addition the aesthetic of masonry is preserved.

Following figure illustrates the strengthening procedure of masonry walls:

Fig: Strengthening of Masonry Walls using FRP Structural Repointing; (a) Grinding of

masonry joints, (b) Masking of masonry to avoid staining, (c) Application of epoxy based paste to

masonry joint, (d) Installation of GFRP Rods (Reference: Strengthening of Masonry Walls by FRP

Structural Repointing by Gustavo Tumialan, Pei-Chang Huang, Antonio Nanni, Pedro Silva)

SUSTAINABILITY IN CONSTRUCTION & CIVIL ENGINEERING

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Home Building Technology

SUSTAINABILITY IN CONSTRUCTION & CIVILENGINEERING

What is sustainability inconstruction and civilengineering?

Sustainability in construction and civil engineering is

the optimization of construction activities in a way

that does not have harmful effects on resources,

surroundings and living ecosystem. It is a way of

minimizing harmful environmental impacts of

construction projects.

Construction involves activities like use of building materials from various sources, use of

machineries, demolition of existing structures, use of green fields, cutting down of tress etc. which

can impact environment in one or more ways.

Why is sustainability important in construction?

Construction has a direct impact on the environment due to following reasons:

1. Generation of waste materials

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SUSTAINABILITY IN CONSTRUCTION & CIVIL ENGINEERING

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2. Emissions from vehicles, machineries

3. Noise pollution due to use of heavy vehicles and construction machineries.

4. Releases of wastes and pollutants into water, ground and atmosphere.

Sustainability assessment of construction projects is essential to the fact that it does not create any

harmful effects on the living ecosystem while optimizing the cost of construction. This is to ensure

the availability of resources for the future generations. Following are the important construction

activities which have large impacts on sustainability in construction and civil engineering:

1. Wastes from demolition of building and structures:

Over billions of tonnes of construction and demolition waste are generated worldwide annually.

These wastes can be hazardous to environment is not disposed off at suitable place without

environmental impact assessment of such wastes. The other alternate is to recycle and reuse of the

demolished building materials to minimize the risk of harmful impacts.

How to make construction waste sustainable?

Following are the steps which need to be followed to make construction waste more sustainable:

Eliminate – avoid producing construction waste in the first place.

Reduce – minimize the amount of waste you produce.

Reuse – reuse the construction wastes in other works.

Recover (recycling, composting, energy) – recycle what you can only after you have reused it.

Dispose – dispose of what is left in a responsible way.

Use of durable construction materials and quality control at site for durability of structure is one step

towards minimization of construction waste generation.

2. Use of Sustainable Building Materials:

Building Materials such as sand and gravel have been used for thousands of years in construction.

The demand for these is increasing day by day as demand for infrastructure development is

SUSTAINABILITY IN CONSTRUCTION & CIVIL ENGINEERING

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increasing.

Uses of construction materials such river sand and gravels also have negative impact on

environment. Excessive sand-and-gravel mining causes the degradation of rivers. Instream mining

lowers the stream bottom, which may lead to bank erosion. This results in the destruction of aquatic

and riparian habitat through large changes in the channel morphology. Impacts include bed

degradation, bed coarsening, lowered water tables near the streambed, and channel instability.

There are many harmful impacts of using river sand and mining of gravels and a detailed study is

required to list all the negative impacts. The use of alternate building materials can reduce the

impact of this on environment.

The alternate to river sand is Manufactured Sand (M-Sand) which can be used in construction works

reduce impacts of mining river sand.

3. Energy Consumption and Green House:

Around 40% of total energy consumption and greenhouse gas emissions are directly due to

construction and operation of buildings. The best of to reduce this impact is the use of green

buildings construction techniques. The use of transparent concrete in buildings also helps to reduce

the use of energy for lighting during day time.

Example of a Sustainable Building Construction

Fig:Example of a Sustainable Building Construction

How to Ensure Sustainable Construction?

Following steps should be taken to for better sustainability of construction activities:

Reduce the supply chains to reduce transport costs

Exercise waste minimization and recycling construction

Building orientation – Choose the building orientation in a way to reduce energy utilization.

Durability and quality of building components, generally chosen to last for the appropriate

refurbishment or demolition cycle.

Use construction materials which are locally available.

SUSTAINABILITY IN CONSTRUCTION & CIVIL ENGINEERING

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NDT TESTING OF MASONRY STRUCTURES

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STRENGTHENING OF FOUNDATIONS

Design buildings and structures as per local topological, climatic and community demands.

Select appropriate construction methods – prefabrication, wood or concrete structures.

Reuse of existing buildings or structures can reduce the construction waste. Reutilizing by

strengthening and rehabilitation of buildings can also save construction cost.

Make site waste management plans not only during construction but also during use or operation.

Minimize energy in construction.

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TENDERING METHODS IN CONSTRUCTION

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Home Construction

TENDERING METHODS IN CONSTRUCTION

There are three types of tendering methods in

construction – by open tendering, selective

tendering, or by negotiation.

tendering methods in construction

Open Tendering Methods inConstruction:

Under open tendering the employer advertises his

proposed project, and permits as many contractors as

are interested to apply for tender documents.

Sometimes he calls for a deposit from applicants, the deposit being returned ‘on receipt of a bona

fide tender’.

However, this method can be said to be wasteful of contractors’ resources since many may spend

time preparing tenders to no effect. Also, knowing their chances of gaining the contract are small,

contractors may not study the contract in detail to work out their minimum price, but simply quote a

price that will be certain to bring them a profit if they win the contract.

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TENDERING METHODS IN CONSTRUCTION

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Thus the employer may be offered only ‘a lottery of prices’ and not necessarily the lowest price for

which his project could be constructed. If he chooses the lowest tender he runs the risk the tenderer

has not studied the contract sufficiently to appraise the risks involved; or the tenderer might not

have the technical or financial resources to undertake the work successfully.

It is true that the employer can check the resources and experience of the lowest bidder and reject

his tender if the enquiry proves unsatisfactory; but several bids may be below the estimated cost of

the job and, if such tenderers appear satisfactory and their bids are not far apart in value, it is

difficult for the employer to choose other than the lowest. The engineer advising the employer may

think there is a risk that all such low bids could prove unsatisfactory, but he cannot advise the

employer what other bid to accept because he has no certainty of information.

Selective Tendering Methods in Construction:

Under selective tendering the employer advertises his project and invites contractors to apply to

be placed on a selected list of contractors who will be invited to bid for the project. Contractors

applying are given a list of information they should supply about themselves in order to ‘pre-qualify’.

The advantage to the employer is that he can select only those contractors, who have adequate

experience, are financially sound, and have the resources and skills to do the work. Also, since only

half a dozen or so contractors are selected, each contractor knows he has a reasonable chance of

gaining the contract and therefore has an incentive to study the tender documents thoroughly and

put forward his keenest price.

However, since contractors have all pre-qualified it is difficult to reject the lowest bid, even if it

appears dubiously low – unless that is due to some obvious mistake.

A problem with both open and selective tendering is that a contractor’s circumstances can change

after he has submitted his tender. He can make losses on other contracts which affect his financial

stability; or may be so successful at tendering that he does not have enough skilled staff or men to

deal with all the work he wins. Neither method of tendering nor any other means of procuring works

can therefore guarantee avoidance of troubles.

Negotiated Tendering Methods in Construction:

Negotiated tenders are obtained by the employer inviting a contractor of his choice to submit

TENDERING METHODS IN CONSTRUCTION

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TAGS Construction Contracts Construction Management Construction Tendering Tender

prices for a project. Usually this is for specialized work or when particular equipment is needed as an

extension of existing works, or for further work following a previous contract.

Sometimes negotiated tenders can be used when there is a very tight deadline, or emergency

works are necessary. A negotiated tender has a good chance of being satisfactory because, more

often than not, it is based on previous satisfactory working together by the employer and the

contractor.

When invited to tender the contractor submits his prices, and if there are any queries these are

discussed and usually settled without difficulty. Thus mistakes in pricing can be reduced, so that both

the engineer advising the employer and the contractor are confident that the job should be

completed to budget if no unforeseen troubles arise.

However, negotiated tenders for public works are rare because the standing rules of public

authorities do not normally permit them. But a private employer or company not subject to

restraints such as those mentioned in the next section can always negotiate a contract, and many do

so, particularly for small jobs. Even when a negotiated tender is adopted it is usual to prepare full

contract documents so that the contract is on a sound basis. Production of the documents also

means they are available for open or selective tendering should a negotiated tender fail, or should

the chosen contractor be unable to undertake the work.

TUNNEL FORM CONSTRUCTION TECHNIQUE

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Home Concrete Technology

TUNNEL FORM CONSTRUCTION TECHNIQUE

Tunnel Form Construction Technique was

invented over 50 years ago. The use of tunnel-form

produces high quality monolithic structures. It

eliminates the use of any subsequent wet trades

(Plastering etc). It is basically an operation to cast

walls and slabs in one operation in a daily cycle. This

technique is highly systematic, earthquake proven

and provides an ideal solution to the critical problem

of sound transmission. It gives a sound reduction of

50 decibels.

Tunnel form is widely used in the construction

of cellular structures with high degree of repetition

such as:

Prisons

Hotels

Student Accommodation (Hostels)

Private Housings

Commercial Developments

Tunnel Form Construction Technique

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TUNNEL FORM CONSTRUCTION TECHNIQUE

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It reduces the heating costs by providing “Thermal Mass” and speeds up the building process.

However, specialist contractors with tunnel-form experience is high recommended in order to tailor

the design to suit best construction method.

Tunnel formwork come in half units and in the form of an inverted “L” which are bolted together at

the top to form each tunnel. The inbuilt wheels and the jacks help the formwork move in and out of

the position and adjusted to the final height.

The factory-made steel formwork can be re-used up to 600 times and it can suit a variety of module

sizes. This makes the method of construction very versatile and extremely economical.

Tunnel-form work allows a 24-hour construction cycle to be achieved and thus the buildability of in-

situ concrete is improved by choosing this type of formwork.

In practice, when the two halves are bolted together, the tunnel formwork will appear like the

following figure.

The Casting Process of Tunnel Formwork:

1) Stage One: Prefabricated Wall reinforcement is placed by crane along the entire wing prior to

casting the kickers (used to position wall formwork).

2) Stage Two: Two and a half tunnel is craned into place, bolted together and ties are added.

TUNNEL FORM CONSTRUCTION TECHNIQUE

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3) Stage Three: The wall concrete is poured.

4) Stage Four: The slab reinforcements are fixed

5) Stage 5: The slab concrete is placed. The formwork system provides for a pour to be wrapped in

tarpaulins and for the use of butane heaters to maintain a sufficiently high temperature for the

concrete to reach its striking strength overnight.

6) Stage 6: The tunnel-forms are removed next day.

7) Stage 7: The process is repeated for the next two bays.

Tunnel form can produce strong and durable in-situ cellular structures. This method of construction

can achieve time savings up to 25% with cost savings of 15%.

Since the concrete finish is very good, the requirement for post construction trades such as

plasterers and electricians are greatly reduced.

TYPES OF BUILDING REPAIR & MAINTENANCE SERVICES

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Home Building Technology Building Maintenance

TYPES OF BUILDING REPAIR & MAINTENANCESERVICES

Building repairs and maintenance services mainly

includes works undertaken for maintaining proper

condition of buildings, its services and works in

ordinary use. The use for which buildings are

designed is the main factor in determining the

required standard of maintenance.

Excessive building maintenance should be avoided.

At the same time, building maintenance should

ensure safety to the occupant or the public and

should comply with the statutory requirements. The

need also depends upon intensity of usage.

The types of building repair and maintenance service works are:

Day to day repairs service facilities

Annual repairs

Special repairs

In addition to above, additions and alterations Works in the buildings, Supply & maintenance of

furniture & furnishing articles should also be done.

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TYPES OF BUILDING REPAIR & MAINTENANCE SERVICES

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Building Repair and Maintenance Services

1. Day to Day Repairs

Day to day repairs include service repairs which arises from time to time in the services of the

buildings such as in plumbing works, water supply, etc. Examples for such repairs are removing

chokage of drainage pipes, man holes, restoration of water supply, replacement of blown fuses,

repairs to faulty switches, watering of plants, lawn mowing, hedge cutting, sweeping of leaf falls etc.

The purpose of this maintenance service is to ensure satisfactory continuous functioning of various

services in the buildings.

2. Annual Repairs

This maintenance service is carried out to maintain the aesthetics of buildings and services as well as

to preserve their life, some works like white washing, distempering, painting, cleaning of lines, tanks

etc. are carried out periodically. These works are planned on year to year basis.

3. Special Repairs

Special repairs of building are undertaken to replace the existing parts of buildings and services

which get deteriorated on ageing of buildings. It is necessary to prevent the structure & services

from deterioration and restore it back to its original conditions to the extent possible.

4. Additions and Alterations

The works of additions/alterations are carried out in buildings to suit the special requirements of

occupants for functional efficiency. The facilities in buildings are updated by carrying out such works.

5. Preventive Maintenance

Preventive maintenance is carried out to avoid breakdown of machinery and occurrence of

maintenance problems in buildings and services. Works of preventive maintenance are carried out on

the basis of regular inspection survey. Preventive maintenance includes works to prevent

deterioration of building parts (which depends on climatic conditions), pollution, fungi, the insect

attack, subsidence, flooding, intensity of usage, careless usage, seepage etc..

TYPES OF CRACK IN CONCRETE STRUCTURES

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Home Building Technology

TYPES OF CRACK IN CONCRETE STRUCTURES

Types of cracks

Structural cracks.

Non Structural Cracks.

Structural Cracks

Structural cracks are those which result from

incorrect design, faulty construction or overloading

and these may endanger the safety of a building and

their inmates.

Non Structural Cracks.

Non Structural cracks occur mostly due to internally induced stresses in building materials. These

cracks normally do not endanger the safety but may look unsightly, create an impression of faulty

work or give a feeling of instability.

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TYPES OF CRACK IN CONCRETE STRUCTURES

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Cracks reappear over repaired surface as rust scales were not removed

Defects in Concrete:

Concrete defects can be broadly classified into two categories :

1. Macro Defects:

If these defects are present, concrete has low strength and will rapidly deteriorate due to easy

ingress of water and other chemicals. Invariably, structure will require repairs within a few years of

its construction. Causes will have to be analysed and defects removed before doing any additional

protective treatment. Often, waterproofing of concrete slabs is carried out superficially and it fails to

give the desired benefit because the defective concrete below this waterproofing layer has not been

treated to seal the macro/micro defects which existed within the concrete slab. The main causes of

these defects are generally due to inadequacies in design and / or construction practices.

2 Micro Defects:

These defects are not visible to the naked eye. They are usually very fine voids caused by large

capillary pores resulting from the use of low grades (strength) of concrete with high water to cement

ratio.

They could also occur due to addition of excess water or high water to cement ratio of concrete mix.

Fine cracks are generally present in concrete and can occur due to various reasons. They do not pose

a serious threat to concrete deterioration initially as they are generally not deep and are

discontinuous. With lapse of time due to variations in temperatures, changes in weather conditions,

changes in loading conditions they increase in depth, length and width and combine with other fine

cracks to create continuous passage for moisture, chlorides, sulphates and other chemicals from the

environment to enter and start corrosion of steel in concrete and other deleterious reactions.

Corrosion of steel and spalling of concrete due to ingress of moisture

To conclude, macro defects and micro defects in concrete are both harmful to the health of buildings

TYPES OF CRACK IN CONCRETE STRUCTURES

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TYPES OF MACHINE FOUNDATIONS

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GROUND IMPROVEMENTTECHNIQUES

and can cause deterioration of concrete depending on the extent of their presence, environmental

conditions around the building and maintenance done during its life cycle. However macro defects by

virtue of being larger can cause faster deterioration and more damage to the structure than the

micro defects.

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TYPES OF FORMWORK (SHUTTERING)

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Home Building Technology Formwork/Shuttering

TYPES OF FORMWORK (SHUTTERING)

Formwork is an ancillary construction, used as a

mould for a structure. Into this mould, fresh concrete

is placed only to harden subsequently. The

construction of formwork takes time and involves

expenditure upto 20 to 25% of the cost of the

structure or even more. Design of these temporary

structures are made to economic expenditure. The

operation of removing the formwork is known as

stripping. Stripped formwork can be reused. Reusable

forms are known as panel forms and non-usable are

called stationary forms.

Timber is the most common material used for

formwork. The disadvantage with timber formwork is that it will warp, swell and shrink. Application

of water impermeable cost to the surface of wood mitigates these defects.

A good formwork should satisfy the following requirements:

1. It should be strong enough to withstand all types of dead and live loads.

2. It should be rigidly constructed and efficiently propped and braced both horizontally and vertically,

so as to retain its shape.

3. The joints in the formwork should be tight against leakage of cement grout.

4. Construction of formwork should permit removal of various parts in desired sequences without

damage to the concrete.

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TYPES OF FORMWORK (SHUTTERING)

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5. The material of the formwork should be cheap, easily available and should be suitable for reuse.

6. The formwork should be set accurately to the desired line and levels should have plane surface.

7. It should be as light as possible.

8. The material of the formwork should not warp or get distorted when exposed to the elements.

9. It should rest on firm base.

Economy in Formwork

The following points are to be kept in view to effect economy in the cost of formwork:

1. The plan of the building should imply minimum number of variations in the size of rooms, floor

area etc. so as to permit reuse of the formwork repeatedly.

2. Design should be perfect to use slender sections only in a most economical way.

3. Minimum sawing and cutting of wooden pieces should be made to enable reuse of the material a

number of times. The quantity of surface finish depends on the quality of the formwork.

Formwork can be made out of timber, plywood, steel, precast concrete or fibre glass used separately

or in combination. Steel forms are used in situation where large numbers of re-use of the same

forms are necessary. For small works, timber formwork proves useful. Fibre glass made of pre-cast

concrete and aluminium are used in cast-in-situ construction such as slabs or members involving

curved surfaces.

Timber Formwork:

Timber for formwork should satisfy the following requirement:

It should be

1. well seasoned

2. light in weight

3. easily workable with nails without splitting

4. free from loose knots

Timber used for shuttering for exposed concrete work should have smooth and even surface on all

faces which come in contact with concrete.

TYPES OF FORMWORK (SHUTTERING)

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Normal sizes of members for timber formwork:

Sheeting for slabs, beam, column side and

beam bottom

25 mm to 40mm thick

Joints, ledges 50 x 70 mm to 50 x 150 mm

Posts 75 x 100mm to 100 x 100 mm

Plywood Formwork

Resin bonded plywood sheets are attached to timber frames to make up panels of required sizes. The

cost of plywood formwork compares favourably with that of timber shuttering and it may even prove

cheaper in certain cases in view of the following considerations:

1. It is possible to have smooth finish in which case on cost in surface finishing is there.

2. By use of large size panels it is possible to effect saving in the labour cost of fixing and

dismantling.

3. Number of reuses are more as compared with timber shuttering. For estimation purpose, number

of reuses can be taken as 20 to 25.

Steel Formwork

This consist of panels fabricated out of thin steel plates stiffened along the edges by small steel

angles. The panel units can be held together through the use of suitable clamps or bolts and nuts.

The panels can be fabricated in large number in any desired modular shape or size. Steel forms are

largely used in large projects or in situation where large number reuses of the shuttering is possible.

This type of shuttering is considered most suitable for circular or curved structures.

Steel forms compared with timber formwork:

1. Steel forms are stronger, durable and have longer life than timber formwork and their reuses are

more in number.

2. Steel forms can be installed and dismantled with greater ease and speed.

3. The quality of exposed concrete surface by using steel forms is good and such surfaces need no

further treatment.

TYPES OF FORMWORK (SHUTTERING)

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4. Steel formwork does not absorb moisture from concrete.

5. Steel formwork does not shrink or warp.

Construction of formwork:

This normally involves the following operations:

1. Propping and centring

2. Shuttering

3. Provision of camber

4. Cleaning and surface treatment

Order and method of removing formwork:

The sequence of orders and method of removal of formwork are as follows:

1. Shuttering forming the vertical faces of walls, beams and column sides should be removed first as

they bear no load but only retain the concrete.

2. Shuttering forming soffit of slabs should be removed next.

3. Shuttering forming soffit of beams, girders or other heavily loaded shuttering should be removed

in the end.

Rapid hardening cement, warm weather and light loading conditions allow early removal of

formwork. The formwork should under no circumstances be allowed to be removed until all the

concrete reaches strength of atleast twice the stresses to which the concrete may be subjected at

the time of removal of formwork. All formworks should be eased gradually and carefully in order to

prevent the load being suddenly transferred to concrete.

Figure 1 to 6 shows formwork for different types of members in civil engineering construction.

Details of timber formwork for RCC beam and slab floor

Figure 1(a): Details of timber formwork for RCC beam and slab floor

Figure 1(b): Details at section (A) shown in above figure

TYPES OF FORMWORK (SHUTTERING)

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Figure 2(a): Elevation

Figure 2(b): Details of timber formwork for circular RCC column

Figure 3(a): 150 3D View

Figure 3(b): Details of timber formwork for square or rectangular RCC column

Figure 4: Sectional plan showing details of timber formwork for an octagonal column

Figure 5: Details of formwork for stair

Figure 6: Timber formwork for RCC wall

Table: Period of removal of formwork

S. No. Description of structural member Period of time

1 Walls, columns and vertical sides of beams 1 to 2 days

2 Slabs (props left under) 3 days

3 Beam soffits (props left under) 7 days

4 Removal of props to slabs

TYPES OF FORMWORK (SHUTTERING)

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TAGS Buildings formwork

(a) For slabs spanning upto 4.5 m 7 days

(b) For slabs spanning over 4.5 m 14 days

5 Removal of props to beams and arches

(a) Spanning upto 6 m 14 days

(b) spanning over 6 m 21 days

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TYPES OF MASONRY WALLS

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Home Building Technology Brick Masonry

TYPES OF MASONRY WALLS

Masonry walls are the most durable part of any

building or structure. They provide strength,,

durability to the structure and also helps to control

indoor and outdoor temperature. It separates a

building from outside world.

Masonry is the word used for construction with

mortar as a binding material with individual units of

bricks, stones, marbles, granites, concrete blocks,

tiles etc. Mortar is a mixture of binding material with

sand. Binding materials can be cement, lime, soil or

any other.

The durability and strength of masonry wall construction depends on the type and quality of material

used and workmanship.

Based on the type of individual units used for masonry walls and their functions, the types of

masonry walls are:

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TYPES OF MASONRY WALLS

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1. Load Bearing Masonry Walls:

Load bearing masonry walls are constructed with bricks, stones or concrete blocks. These walls

directly transfer loads from the roof to the foundation. These walls can be exterior as well as interior

walls. The construction system with load bearing walls are economical than the system with framed

structures.

Load Bearing Masonry Wall

Fig: Load Bearing Masonry Wall

The thickness of load bearing walls is based on the quantity of load from roof it has to bear. For

example a load bearing wall with just a ground floor can have its outer walls of 230mm, while with

one or more floors above it, based on occupancy type, its thickness may be increased.

The load bearing walls can be reinforced or unreinforced masonry walls.

2. Reinforced Masonry Walls:

Reinforced masonry walls can be load bearing walls or non-load bearing walls. The use of

reinforcement in walls helps it to withstand tension forces and heavy compressive loads. The un-

reinforced masonry walls are prone to cracks and failure under heavy compressive loads and during

earthquakes. They have little ability to withstand lateral forces during heavy rain and wind. Cracks

also develop in un-reinforced masonry walls due to earth pressure or differential settlement of

foundations.

To overcome such problems, reinforced masonry walls are used. Reinforcement in walls are at

required intervals both horizontally and vertically is used. The size of reinforcement, their quantity

and spacing are determined based on the loads on the walls and structural conditions.

3. Hollow Masonry Walls:

Hollow or Cavity masonry walls are used to prevent moisture reaching the interior of the building by

providing hollow space between outside and inside face of the wall. These walls also helps in

TYPES OF MASONRY WALLS

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temperature control inside the building from outside wall as the hollow space restricts heat to pass

through the wall.

Fig: Hollow Masonry Wall

When the wall is exposed to moisture for a sustained period and penetrates through the outer face,

the water reaches the cavity or the hollow space and flows down. Then they are drained through the

weep holes to the exterior of the building. These hollow spaces may be coated with water repellent

coating or damp-proofing to further reduce the ingress of moisture.

4. Composite Masonry Walls:

These walls are constructed with two or more units such as stones or bricks and hollow bricks. This

type of masonry wall construction is done for better appearance with economy.

In composite masonry walls, two wythes of masonry units are constructed bonding with each other.

While one wythe can be brick or stone masonry while the other can be hollow bricks. A wythe is a

continuous vertical section of masonry one unit in thickness.

Fig: Composite Masonry Wall

These wythes are interconnected either by horizontal joint reinforcement or by using steel ties.

5. Post-tensioned Masonry Walls:

Post-tensioned masonry walls are constructed to strengthen the masonry walls against the forces

that may induce tension in the wall such as earthquake forces or wind forces.

These walls are constructed from the foundation level and post-tensioning rods are anchored into the

foundation. These rods are run vertically between the wythes or in the core of concrete masonry

units.

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DEFECTIVE CONCRETE REMOVALTECHNIQUES

After the masonry wall construction is completed and cured, these rods are tensioned and anchored

on the steel place at the top of the wall.

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TYPES OF MORTAR AS BINDING MATERIAL

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Home Building Technology Brick Masonry

TYPES OF MORTAR AS BINDING MATERIAL

Types of of Mortar as binding material:

The kind of binding material for a mortar is selected

by keeping in mind several factors such as expected

working conditions, hardening temperature, moisture

conditions, etc. According to the kind of binding

material, the mortars are classified into the following

five categories:

i. Lime mortar

ii. Surkhi mortar

iii. Cement mortar

iv. Gauged mortar

v. Gypsum mortar.

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TYPES OF MORTAR AS BINDING MATERIAL

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i. Lime mortar:

In this type of mortar, the lime is used as binding material. The lime may be fat lime or hydraulic

lime. The fat lime shrinks to a great extent and hence it requires about 2 to 3 times its volume of

sand. The lime should be slaked before use. This mortar is unsuitable for water-logged areas or in

damp situations. It possesses good cohesiveness with other surfaces and shrinks very little. It is

sufficiently

durable, but it hardens slowly. It is generally used for lightly loaded above-ground parts of buildings.

brick-masonry

ii. Surkhi mortar:

This type of mortar is prepared by using fully surkhi instead of sand or by replacing half of sand in

case of fat lime mortar. The powder of surkhi should be fine enough to pass BIS No. 9 sieve and the

residue should not be more than 10% by weight. The surkhi mortar is used for ordinary masonry

work of all kinds in foundation and superstructure. But it cannot be used for plastering or pointing

since surkhi is likely to disintegrate after some time".

iii. Cement mortar:

In this type of mortar, the cement is used as binding material. Depending upon the strength

required and importance of work, the proportion of cement to sand by volume varies from 1:2 to 1:6

or more. It should be noted that surkhi and cinder are not chemically inert substances and hence

they cannot be used as adulterants with matrix as cement. Thus the sand only can be used to form

cement

mortar. The proportion of cement with respect to sand should be determined with due regard to the

specified durability and working conditions. The cement mortar is used where a mortar of high

strength and water-resisting properties is required such as underground constructions, water

saturated soils, etc.

iv. Gauged mortar:

To improve the quality of lime mortar and to achieve early strength, the cement is sometimes added

to it. This process is known as the gauging. It makes lime mortar economical, strong and dense. The

usual proportion of cement to lime by volume is about 1:6 to 1 :8. It is also known as the composite

mortar or lime-cement mortar and it can also be formed by the combination of cement and clay. This

mortar may be used for bedding and for thick brick walls.

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v. Gypsum mortar:

These mortars are prepared from gypsum binding materials such as building gypsum and anhydrite

binding materials.

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UNIT COST METHOD OF ESTIMATION

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Home Construction Management Cost Estimation

UNIT COST METHOD OF ESTIMATION

Unit Cost Method of Estimation starts with

dividing a construction project into various

components or elements for the purpose of cost

estimation. Then cost of each of the project’s

components or elements are assessed and their cost

estimation is calculated. Sum of costs of each project

elements gives the total construction cost of the

project. The unit cost method of estimation can be

used for project design estimates as well as for bid

estimates.

Construction cost estimates are of three types

mentioned below:

1. Preliminery Cost Estimates

2. Detailed Cost Estimates

3. Engineer’s Cost Estimates

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UNIT COST METHOD OF ESTIMATION

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During the preliminery cost estimate, as cost details of every minute elements are not of much

importance, the project is divided into major components and cost estimate of these major units are

calcualted based on the past project experiences. The cost of euipments if any is also included. For

example, estimating the cost of entire floor based on its area.

During detailed Cost estimates, the project is divided into components of various major systams

and cost of each components is estimated to calculate project cost. For example, cost of installation

of any equipment, cost of beams, columns or walls etc.

During Engineer’s cost estimates, each of the components of the major systems of the project is

divided into various components that contributes to the cost of the major systems. For example, for

cost estimation of an RCC column, the components are concrete, which is also divided into cement,

sand and aggregates, reinforcement steel, formworks etc. The unit cost of each of these materials

are considered by calculating the cost of an RCC column.

Unit Cost Method of Estimation

For bid estimates, the unit cost method of estimation can also be used even though the contractor

divides the project into different levels in a hierarchy as follows:

1. Subcontractor Quotations: The general contractor of the construction project may get

quotations for various items from the subcontractors. The rates prescribed by the subcontractors

for various items of the projects can be used for the total construction cost etimate for the

project. However, the reliability of accuracy of the cost depends on the method of cost estimates

selected by the subcontractor.

2. Quantity Takeoffs: The division of a construction project into various items of quantities that are

measured from the engineer’s plan will result in a procedure similar to that adopted for a detailed

estimate or an engineer’s estimate by the design professional. The levels of detail may vary

according to the desire of the general contractor and the availability of cost data.

3. Construction Procedures: If the construction procedure of a proposed project is used as the

basis of a cost estimate, the project may be decomposed into items such as labor, material and

equipment needed to perform various tasks in the projects.

Formula for Unit Cost Method:

Suppose that a construction project is divided into “n” elements for cost estimation. Let “Qi” be the

quantity of the ith element and ui be the corresponding unit cost. Then, the total cost of the project

is given by:

UNIT COST METHOD OF ESTIMATION

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where n is the number of units. The unit cost of element ui is estimated based on the method of

construction, technology used, type of materials used etc.

Factored Unit Cost Estimate Formula

Sometimes during the cost estimate, there can be some of the minute components which may not

have been considered or there can be some variations w.r.t time. In such cases, the cost of units are

factored as an allowance for variations or the elements not considered in the estimates. The formula

for factored unit cost estimation is as follows:

where Ci is the purchase cost of a major component i and fi be a factor accounting for the cost

variation of the item, n is the number of components included in the construction project.

Formula Based on Labor, Material and Equipment

Suppose that a construction project is decomposed into n tasks. Let Qi be the quantity of work for

task i, Mi be the unit material cost of task i, Ei be the unit equipment rate for task i, Li be the units

of labor required per unit of Qi, and Wi be the wage rate associated with Li. In this case, the total

cost y is:

Note that WiLi yields the labor cost per unit of Qi, or the labor unit cost of task i. Consequently, the

units for all terms in Equation above are consistent.

WALLS- TYPES, FEATURES AND DESIGN CONCEPT

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Home Building Technology

WALLS- TYPES, FEATURES AND DESIGNCONCEPT

Walls- Types, Features and Design Concept

FUNCTION OF WALLS

To provide protection from weather, animal

To divide the areas

Act as sound barriers

As fire walls to attenuate the spread of fire from

one building unit to another

Separate the interior spaces

To improve the building appearance

To provide privacy

MATERIAL FOR WALL CONSTRUCTION

Timber, brick, concrete block, reinforced concrete can be used for wall construction.

Good for wall construction due it’s durability, beauty and able to provide comfortable area

Cengal is suitable to be used at hot and cold climate area

Meranti can be used for all types of construction in the building.

Reinforced concrete used for precast concrete panel

WALL CLASIFICATION

There are 2 types of wall that is:

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WALLS- TYPES, FEATURES AND DESIGN CONCEPT

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a) Load Bearing Wall

Able to carry the load from above (own weight & load from roof) and transfer it to the foundation.

b) Non Load Bearing Wall

Only carry their own weight

LOAD BEARING WALL

It can be exterior wall or interior wall. It brace from the roof to the floor.

Pre Cast Concrete Wall

Retaining Wall

Masonry Wall

Pre Panelized Load Bearing Metal Stud Walls

Engineering Brick Wall (115mm, 225mm)

Stone Wall

As the height of the building increased, required thickness of wall and resulting stress on

foundation will also increase and cause it to be uneconomical.

Able To Carry Other Structure Weight Beside Its Own Weight

WALLS- TYPES, FEATURES AND DESIGN CONCEPT

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Removing a section of a load bearing wall to create a pass-through requires adding a new beam and

columns to support the floor above.

Fig: Precast Concrete Wall (Load Bearing Wall)

Fig: Pre Panelized Load Bearing Metal Stud Walls

Fig: Stone Wall (Load Bearing Wall)

Fig: Precast Concrete Wall (Load Bearing Wall

Fig; Masonry Wall

WALLS- TYPES, FEATURES AND DESIGN CONCEPT

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Fig: Load Bearing Retaining Wall

NON LOAD BEARING WALL

known as interior wall (doesn’t carry other load than its own load)

Types of non load bearing wall

a) Hollow Concrete Block

b) Façade Bricks

c) Hollow Bricks

d) Brick Wall (115mm, 225mm)

Fig: Brick Wall (Non Load Bearing Wall)

Fig: Semi Hollow Brick (Non Load Bearing Wall)

Fig: Façade Brick Wall (Non Load Bearing Wall)

Fig: Hollow Concrete Block Wall (Non Load Bearing Wall)

BRICK’S BONDING

Stretcher Bond

English Bond

Flemish Bond

Raking Bond

English Garden Wall Bond

Common / American Bond

Flemish Garden Wall Bond

Running Bond

WALLS- TYPES, FEATURES AND DESIGN CONCEPT

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Herringbone Bond

Fig: Header: A brick which is laid in a way that only the short end is visible in the wall

Fig: Stretcher: A brick which is laid in a way that allows only the longer side of the brick to be

exposed.

Fig: Flemish Bond

Alternate bricks are placed as header and stretcher in every course. Each header is placed centrally

between the stretchers immediately above and below. This is not as strong as the English bond at 1

brick thick . Can be successfully applied in cavity wall.

Fig: English Bond

Alternative courses of headers and stretchers; one header placed centrally above each stretcher.

This is a very strong bond when the wall is 1 brick thick (or thicker). One of the strongest brickwork

bond patterns.

Fig: Stretcher Bond

Easiest bond to lay & minimizes the amount of cutting required. Originally used for single brick walls,

now called 1/2 brick walls it became the obvious choice for cavity walls as less cutting was required.

Fig: Raking Bond

WALLS- TYPES, FEATURES AND DESIGN CONCEPT

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Herringbone and diagonal bonds can be effective within an exposed framed construction, or

contained within restraining brick courses.

Fig: English Garden Wall Bond

An alternative version of English bond with header courses being inserted at every fourth or sixth

course. This is a correspondingly weaker bond. Suitable for free standing wall.

Fig: Common / American Bond

A brickwork pattern in which all rows are stretchers, except an eighth row of headers

Fig: Flemish Garden Wall Bond

In this variant of Flemish bond, one header is placed at every third stretcher

Fig: Running Bond

Consist of all stretchers. No header used in this bond so metal ties are used. Cavity wall construction

& veneered walls of brick.

Fig: Herringbone Bond

It is a purely decorative bond. It is used in floor and wall panels.

CAVITY WALL

“A wall constructed in 2 leaves / skins with a

space / cavity between them”

“A type of building wall construction

consisting of an outer wall fastened to inner

wall separated by an air space”

FUNCTION

To prevent the penetration of rain to the internal surface of the wall

WALLS- TYPES, FEATURES AND DESIGN CONCEPT

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SHEAR WALL

A framed wall designed to resist lateral wall. It is a vertical elements of the horizontal

force resisting system

It is used to resist wind and earthquake loading on a building.

It is typically a wood frame stud walls covered with a structural sheathing material

like plywood.

WALL FAILURE

Vertical bowing and horizontal bending or collapse of wall is usually caused by the wall not

resisting vertical pressures from foundation or upper floors & roofs or horizontal pressures

from strong winds and retained earth.

Usual cause for failure of wall are as follows:

– Overloading the wall, deflection of beam above the wall will affect the wall below.

– Foundation failure

– Earthquake

– Timber pest damage weakened the timber wall

– Poor workmanship (improper brickwork)

Fig: Brick Wall Crack

Fig: Brick Wall Failure At The Roof Level

Fig: Cracked Wall

Where Do Designers Go Wrong

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Home Building Technology Building Materials

Where Do Designers Go Wrong

Where Do Designers Go Wrong? Typical

Problems in Wood Construction

Wood and wood products are relatively simple

engineering materials, but the conception, design,

and construction process is fraught with problems

and places to err. In using wood in its many forms

and with its unique inherent characteristics, there are

problem areas which seem to present easily

overlooked pitfalls. As gentle reminders for caution,

some of these areas are discussed below.

Wood and water do not mix well

Wood is hygroscopic and, unless preservative-treated, rots when its MC rises above 20%. It must be

protected in some way. Minor roof leakage often leads to pockets of decay, which may not be

noticed until severe decay or actual failure has occurred. Stained areas on wood siding or at joints

may indicate metal fastener rust associated with a wet spot or decay in adjoining, supporting

members. In many cases what appears to be a minor problem ends up as major and sometimes

extensive repair is required. Improper installation or lack of an adequate vapor barrier can result in

serious decay in studs within a wall as well as paint peel on exterior surfaces. Ground contact of

wood members can lead to decay as well as providing ready access to wood-deteriorating termites.

Placement of preservative-treated members between the ground and the rest of the structure (as a

bottom sill in a residence) is usually a code requirement. Timber arches for churches, office buildings,

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and restaurants are usually affixed to a foundation by steel supports; if the supports are not properly

installed, they may merely form a receptacle for rain or condensation to collect, enter the wood

through capillary action, and initiate decay. Once decay is discovered, major repair is indicated;

preservative treatment to a decayed area may prevent further decay, but it will not restore the

strength of the material. Elimination of the causal agent (moisture) is paramount. Visible decay

usually means that significant fungal deterioration has progressed for 1 to 2 feet along the grain of a

member beyond where it is readily identifiable.

Pay attention to detail

In an area that has high relative humidity, special precautions should be taken. A structure that is

surrounded by trees or other vegetation or that prevents wind and sun from drying action, is prone

to high humidity nearly every day, particularly on a north side. Likewise, if the structure is near a

stream or other source of moisture, it may have moisture problems. Home siding in this type of

atmosphere may warp or exhibit heavy mildew or fungal stain. Buildings with small (or nonexistent)

roof overhangs are susceptible to similar siding problems if the siding is improperly installed,

allowing water or condensation to enter and accumulate behind the siding. Inadequate sealing and

painting of a surface can add to the problem. In a classic example, a three-story home on a tree-

shaded area next to a small stream and with no roof overhang had poorly installed siding, which

subsequently warped so badly that numerous pieces fell off of the home. Poor architecture, poor

site, poor construction practice, and poor judgment combined to create a disaster. This type of

problem becomes magnified in commercial structures, where large surfaces are covered with wood

panel products that tend to swell in thickness at their joints if they are not properly sealed and

protected from unusual moisture environments. If properly installed, these materials provide

economical, long-term, excellent service.

Wood is viscoelastic and will creep under load

This has created widespread problems in combination with clogged or inadequate drains on flat

roofs. Ponding, with increasing roof joist deflection, can lead to ultimate roof failure. In situations

where floor or ceiling deflection is important, a rule of thumb to follow is that increased deflection

due to long-term creep may be assumed to be about equal to initial deflection under the design

loading. In some cases the occupants of a building will report that they can hear wood members

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creaking, particularly under a snow load or ponding action. This is a good indication that the

structure is overstressed and failure, or increasing creep deformation with impending failure, is

imminent. Deflection measurements over a several-week period can often isolate the problem and

lead to suitable reinforcement.

Repair structural members correctly

Epoxy resin impregnation and other techniques are often used to repair structural members. These

methods are said to be particularly effective in repairing decayed areas in beams and columns.

Removal of decayed spots and replacement by epoxy resin is acceptable only if the afflicted

members are also shielded from the original causal agent—excess moisture or insect attack.

Likewise, if a wood adhesive must be used as a fastener in an exposed area, use a waterproof

adhesive; “water-resistant” or carpenter’s glue won’t do. Although several wood adhesives will

produce a wood-towood bond stronger than the wood itself, most of these adhesives are formulated

for, and used in, furniture manufacture, where the wood is dry (about 6 to 7% MC) at time of

fabrication and is presumed to be kept that way. Structural-use adhesives (unless they are specially

formulated epoxy or similar types) may be used where the wood is not above about 20% MC.

Structural-use adhesives must also be gap fillers; i.e., they must be able to form a strong joint

between two pieces of wood that are not always perfectly flat, close-fitting surfaces. In addition, the

adhesive should be waterproof. The most common and readily available adhesive that meets these

criteria is a phenol-resorcinol-formaldehyde adhesive, a catalyzed, dark purple-colored adhesive

which is admirably suited to the task.

Protect materials at the job site

Failure to do so has caused plywood and other panel products to become wet through exposure to

rain so that they delaminate, warp severely, or swell in thickness to the point of needing to be

discarded. Lumber piled on the ground for several days or more, particularly in hot, humid weather,

will pick up moisture and warp or acquire surface fungi and stain. This does not harm the wood if it is

subsequently dried again, but it does render it esthetically unfit for exposed use. To repeat, wood

and water do not mix.

Take time to know what species and grades of lumber you require, and then inspect it

Engineers and architects tend to order the lumber grade indicated by mathematical calculations;

carpenters use what is provided to them. Unlike times past, no one seems to be ultimately

responsible for appropriate quality until a problem arises and expensive rework is needed. Case in

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point: a No. 2 grade 2-by, which is tacitly presumed to be used in conjunction with other structural

members to form an integrated structure, is not satisfactory for use as scaffolding plank or to serve

a similar, critical function on the job site where it is subjected to large loads independent of

neighboring planks.

Inspect the job site

Make sure that panel products, such as plywood, OSB, or flakeboard, are kept under roof prior to

installation. Stacked on the ground or subjected to several weeks of rainy weather, not only will

these panels warp, but they may lose their structural integrity over time. “An ounce of prevention,”

etc.

Be aware of wood and within-grade variability due to the uniqueness of tree growth and

wood defects

It is often wise to screen lumber to cull out pieces that have unusually wide growth rings or wood

that is from an area including the pith (center) of the tree. This material often tends to shrink along

its length as much as ten times the normal amount due to an inherently high microfibrillar angle in

growth rings close to the pith. In truss manufacture this has resulted in the lower chords of some

trusses in a home (lower chords in winter being warmer and drier) to shorten as they dry, while the

top chords do not change MC as much. The result is that the truss will bow upward, separating by as

much as an inch from interior partitions — very disconcerting to the inhabitants and very difficult to

cure. A good component fabricator is aware of this phenomenon and will buy higher-quality material

to at least minimize the potential problem. Conversely, avoid the expensive; “cover all the bases”

approach of ordering only the top grade of the strongest species available.

Inspect all timber connections during erection

Check on proper plate fasteners on trusses and parallel chord beams after installation; plates should

have sufficient teeth fully embedded into each adjoining member. Occasionally in a very dense piece

the metal teeth will bend over rather than penetrate into the wood properly. A somewhat similar

problem arises if wood frames or trusses are not handled properly during erection; avoid undue out-

of-plane bending in a truss during transport or erection since this will not only highly stress the

lumber but may also partially remove the plates holding the members together. Bolted connections

must be retightened at regular intervals for about a year after erection to take up any slack due to

subsequent lumber drying and shrinkage.

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Perhaps one of the major causes of disaster is the lack of adequate bracing during frame

erection

This is a particularly familiar scenario on do-it-yourself projects, such as by church groups or

unskilled erection crews. Thin, 2-by lumber is inherently unstable in long lengths; design manuals

and warning labels on lumber or product shipments testify to this, yet the warnings are continually

disregarded. Unfortunately, the engineer, designer, or architect and materials supplier often are

made to share the resulting financial responsibility.

Be aware of wood’s orthotropicity

A large slope of grain around a knot or a knot strategically poorly placed can seriously alter bending

or compressive strength and are even more limiting in tension members. Allowable design values for

tension parallel to the grain are dictated by an ASTM standard (ASTM, 1992) as being 55% of

allowable bending values because test results have indicated that slope of grain or other defects

greatly reduce tensile properties. Different orthotropic shrinkage values, due to grain deviations or

improper fastening of dissimilar wood planes, can lead to warpage and subsequent shifts in load-

induced stresses. Care must be taken when using multiple fasteners (bolts, split rings, etc.) to avoid

end splits as wood changes MC, particularly if the members are large and only partially dried at the

time of installation. When installing a deep beam that is end-supported by a heavy steel strap

hanger, it is often best to fasten the beam to the hanger by a single bolt, installed near the lower

edge of the beam. This will provide the necessary restraint against lateral movement, whereas

multiple bolts placed in a vertical row will prevent the beam from normal shrinkage in place and

often induce splits in the ends of the beam as the beam tries to shrink and swell with changes in

relative humidity. Not only are the end splits unsightly, but they also reduce the horizontal shear

strength of the beam at a critical point. In addition, if the beam has several vertically aligned bolts

and subsequently shrinks, the bolts will become the sole support of the beam independent of the

strap hanger, as shrinkage lifts the beam free of the supporting strap hanger.

Use metal joist hangers and other fastening devices; they add strength and efficiency in

construction to a job

Toe-nailing the end of a joist may restrain it from lateral movement, but it does little to prevent it

from overturning if there is no stabilizing decking. Erection stresses caused by carpenters and

erection crews standing or working on partially completed framework are a leading cause of member

failure and job site injury.

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In renovating old structures, as long as decay is not present, the old members can be

reused

However, because large sawn timbers tend to crack as they dry in place over a period of time, the

members must be regraded by a qualified grader. The dried wood (usually well below 19% MC) has

increased considerably in strength, perhaps counterbalancing the decrease in strength due to deep

checking and/or splitting. End splits over supports should be carefully checked for potential shear

failure.

Wood and fire pose a unique situation

Wood burns, but in larger sizes—15 cm (6 in.) and larger—the outer shell of wood burns slowly and,

as the wood turns to charcoal, the wood becomes insulated and ceases to support combustion. Once

the fire has been extinguished, the wood members can be removed, planed free of char, and reused,

but at a reduced section modulus. Smaller members can also be fire retardant–treated to the degree

that they will not support combustion. However, treating companies should be consulted in regard to

any possible strength-reducing effects due to the treatment, particularly where such members are to

be subjected to poorly ventilated areas of high temperature and high relative humidity, as in attic

spaces. In recent years newly developed fire retardant treatments have reacted with wood when in a

high temperature–high relative humidity environment to seriously deteriorate the wood in treated

plywood or truss members. These chemicals, presumably withdrawn from the marketplace, act

slowly over time, but have contributed to structural failure in the attics of numerous condominium

type buildings. Preventive measures where such problems may be anticipated include the addition of

thermostatically controlled forced-air venting (the easiest and probably most effective measure); the

addition of an insulation layer to the underside of the roof to reduce the amount of heat

accumulation in the attic due to radiant heat absorption from the sun; and the installation of a vapor

barrier on the floor of the attic to reduce the amount of water vapor from the underlying living units.

In using preservative-treated wood it is always best—certainly so when dealing with larger members

— to make all cuts to length, bore holes, cut notches, etc., prior to treatment. Depth of preservative

treatment in larger members is usually not complete, and exposure of untreated material through

cutting may invite decay. Determination of the depth of penetration of a preservative by noting a

color change in the wood is hazardous; penetration may be more or less than is apparent to the eye.

Deep checking as a large member dries will often expose untreated wood to fungal organisms or

insects. Periodic treatment by brushing preservative into exposed cracks is highly recommended.

This is particularly true for log home–type construction. Modern log home construction utilizes

partially seasoned materials with shaped sections, which not only increase the insulative quality of

the homes but also tend to balance, or relieve, shrinkage forces to reduce cracking. Treated or raised

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TAGS Building Materials wood

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CONTACT PRESSURE AND DEFORMATION PATTERN

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PARTIAL-DEPTH REPAIR OF PAVEMENTS

nonwood foundations are recommended. Wood is an excellent construction material, tested and used

effectively over the years for a myriad of structural applications—provided one takes the time to

understand its strengths and weaknesses and to

pay appropriate attention to detail. Knowing species and lumber grade characteristics and how a

member is to be used, not only in a structure but also during erection, can go a long way toward

trouble-free construction.

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WRITING SPECIFICATIONS FOR CONSTRUCTION CONTRACTS

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Home Construction

WRITING SPECIFICATIONS FOR CONSTRUCTIONCONTRACTS

In writing specifications for construction contracts,

care must be taken to ensure consistency of

requirements throughout and conformity with what is

written in other documents. This consistency can be

promoted if one person drafts all the documents or, if

parts are written by others, one person carefully

reads through the whole finished set of documents.

An inconsistency in the documents can give rise to a

major dispute under the contract, having a serious

effect on its financial outcome.

construction specification

Some principle guidelines for writing specifications are as follows.

• The layout and grouping of subjects should be logical. These need planning out beforehand.

• Requirements for each subject should be stated clearly, in logical order, and checked to see all

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WRITING SPECIFICATIONS FOR CONSTRUCTION CONTRACTS

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aspects are covered.

• Language and punctuation should be checked to see they cannot give rise to ambiguity.

• Legal terms and phrases should not be used.

• To define obligations the words ‘shall’ or ‘must’ (not ‘should’ or ‘is to’, etc.) should be used.

• Quality must be precisely defined, not described as ‘best’, etc.

• Brevity should be sought by keeping to essential matters.

It is not easy to achieve an error-free specification. It is of considerable assistance to copy model

clauses that, by use and modification over many previous contracts, have proved satisfactory in

their wording. Such model clauses can be held on computer files so they are easy to reproduce and

modify to make relevant to the particular project in hand. Copying whole texts from a previous

specification which can result in contradictory requirements should not be adopted. Entirely new

material is quite difficult to write and will almost certainly require more than one attempt to get it

satisfactory.

The specification has to tell the contractor precisely:

• The extent of the work to be carried out;

• The quality and type of materials and workmanship required;

• Where necessary, the methods he is required to use, or may not use, to construct the works.

Under the first an informative description is given of what the contractor is to provide and all special

factors, limitations, etc. applied. Under the second the detailed requirements are set out. The extent

of detail adopted should relate to the quantity and importance of any particular type of work in

relation to the works required. Thus the specification for concrete quality may be very extensive

where much structural concrete is to be placed; but it may be quite short if concrete is only required

as bedding or thrust blocks to a pipeline. A ‘tailormade’ specification appropriate to the nature of the

work in the contract should be the aim.

Repetition of requirements should be avoided. If requirements appear in two places, ambiguity

WRITING SPECIFICATIONS FOR CONSTRUCTION CONTRACTS

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TAGS Civil Engineering Specifications Construction Contracts Construction Management ConstructionSpecification

writing specification

or conflict can be caused by differences of wording. Also there is a danger that a late alteration alters

one statement but fails to alter its repetition elsewhere.

The third of the items noted above needs careful consideration, as there may be dangers and

liabilities involved in telling the contractor how to go about his work. Some methods may need to be

specified, such as the requirements concerning the handling and placing of concrete, but these and

similar matters should be specified under workmanship and materials clauses. Other directions on

method should be given only if essential for the design. For instance, if it is necessary to under-pin

or shore up an existing structure, the exact method used should not be specified for, if the

contractor follows the method and damage ensues, the liability for damage may lie on the designer.

Usually there is no need to specify a particular method, but there may be a need to rule out certain

methods; for example, that the contractor is not to use explosives.

It is important to avoid vague phraseology such as requiring the contractor to provide ‘matters,

things and requisites of any kind’, or ‘materials of any sort or description’, etc. d or reasonably to be

inferred from the contract.’ Similarly the phrase ‘excavation in all materials’ is ineffectual. The

drafter might think it covers any rock encountered but it does not if the geological data supplied with

the contract or reasonably available to the contractor provides no evidence of the existence of rock.

Definitions such as those used in the Civil Engineering Standard Method of Measurement should be

followed.

WRITING SPECIFICATIONS FOR CONSTRUCTION CONTRACTS

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