Weir Specification (Especificaciones técnicas de construcción de vertedeteros)

8/20/2019 Weir Specification (Especificaciones técnicas de construcción de vertedeteros)

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2.0 WEIR INTAKE STRUCTURE

ITEM 2.1 COFFERDAM

2.1.1 GENERAL

2.1.1.1 DESCRIPTION

To ensure that all areas are free from the disturbance that the water will

cause to the constructions, this item shall contain but not limited to the

following works:

a. Excavation required for the construction of the weir

b. Disposal of the excavated material

c. Backfilling around the weir structure to the original ground level or as

required by the plans

d. Works to make sure that all areas are free from water at all times during

construction such as pumping and dewatering

e. Sheet piling (if necessary)

f. Construction and removal of temporary structures such as cofferdam,

pipes, canals and ditches.

g. Diversion of existing waterways

The Contractor shall submit to the Engineer a comprehensive plan and

construction methodology on how he proposes to achieve this task. This

shall include all the materials, labor, equipment, tools, pumping units, etc.

2.1.2 EXECUTION

The Contractor shall have an engineering documentation for every cofferdam

installation activity and is accessible for review by the Engineer and

installation personnel. It must also provide a means of being held firmly and

securely against the hull in the event of a loss of differential pressure. All

patches must be secured such that they cannot rotate or move out of

alignment with the hull opening.

2.1.3 MEASUREMENT/BASIS OF PAYMENT

Accomplishment shall be expressed in percentage of all accepted work items

accomplished included of the Bill of Quantities for the period covered.

The accepted quantities measured and prescribed above shall be paid for at the

unit price indicated in the Bill of Quantities. This payment shall constitute full

payment of all work done related to care of water, materials, labor, equipment,

tools and incidentals necessary to complete this prescribed work item.

ITEM 2.2 CLEARING AND GRUBBING

2.2.1 GENERAL

2.2.1.1 DESCRIPTION


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The Work under this item includes providing all labor, materials, tools and

equipment necessary for clearing, grubbing, removing and disposing of all

vegetation and debris (including earthen materials incidentally removed

with vegetation and debris), and removing structures and obstructions

located within the limits shown on the plans or designated by the Engineer,

except such objects as are designated to remain in place or are to be

removed in accordance with other sections of these Specifications. The

Work shall also include the preservation from injury or defacement of all

vegetation and objects designated to remain

2.2.2 EXECUTION

2.2.2.1 CLEARING

Clearing shall consist of removing shrubs, and brush and disposal of all

debris including rubbish occurring within areas to be cleared. Stumps,

roots, brush, and other vegetation in the areas to be cleared shall be cut off

below the original ground surface.

2.2.2.2 HAND – CLEARING

In areas where Hand Clearing is indicated on the Plans or designated by the

Engineer, no equipment on wheels shall be used. Care shall be taken to

insure that the grass, moss cover, or the natural ground as indicated in the

plan is not disturbed.

2.2.2.3 SELECTED TREE REMOVAL

Trees designated by the Engineer, outside of the normal clearing and

grubbing and/or hand clearing limits, shall be removed and disposed of in

accordance with this item. Trees to be removed may be designated by the

Engineer at any time during the performance of the contract, and may be

subject to the conditions specified under Hand Clearing. Trees designated

for selective removal shall be cut off within six inches of the ground.

2.2.2.4 REMOVE AND RELOCATE BUSH OR TREE

Bushes or trees shown on the Plans for removal and relocation shall be

removed and relocated as directed by the Engineer. Bushes and treesdesignated for removal and relocation shall be carefully removed with

enough of the root wad kept intact to ensure the survival of the bush or tree

in its new locations. Bushes and trees designated for removal and

relocation that are damaged, or that do not survive as a result of the

transplanting, shall be replaced by the Contractor at its expense. The

relocated bush or tree shall be placed to original depth at a location as

directed by the Engineer.

2.2.2.5 GRUBBING

Grubbing shall consist of removal and disposal of stumps, roots larger than

seventy five (75) millimeters in diameter and matted roots from designated

grubbing areas. Logs and other organic or metallic debris and abandoned

concrete footings shall be removed.

2.2.2.6 STRIPPING


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Those areas that will be disturbed by excavation, filling, access road

development, or compaction by equipment will be soil stripped to a depth of

one hundred fifty (150) meters taking into consideration all planned erosion

and sediment control practices shall be in place and functioning properly

prior to soil stripping.

2.2.3 PRODUCTS

2.2.3.1 STORAGE PILES

Topsoil that is suitable for reuse shall be placed in storage piles convenient

to areas that are to receive application of topsoil. Topsoil shall be kept

separate from the other excavated materials and shall be free of roots,

stones larger than five (5) centimeters and other undesirable materials that

would interfere with the planting.


The area that is to be cleared and grubbed to be paid for will be the number of

square meter measure on the ground or site of the weir acceptably cleared in

conformity with the plans or as directed by the Engineer.

The accepted quantities, measured as prescribed above shall be paid for at the

contract unit price for each of the particular pay items listed and included in

the Bill of Quantities. The payment shall constitute full compensation for the

removal and disposal of cleared and grubbed materials including all labor,

equipment tools and incidentals necessary to complete the work prescribed in

this item.

ITEM 2.3 EARTH EXCAVATION

2.3.1 GENERAL

The excavation will generally refer to open excavation of foundation wet or dry

and in all sorts of soils.

2.3.1.1 DESCRIPTION

This item shall consist of the necessary excavation for foundations and

other structures indicated in the Plans, in accordance to these

specifications and in conformity with the lines, grades and dimensions

shown in the Drawings as indicated and established by the Engineer. The

Contractor shall be aware of obstructions such as pipes, conduits and

cables in the areas to be excavated. The Contractor shall verify the

existence and location of such obstructions before the start of excavation.

All excavated materials shall be disposed properly and deposited at

locations indicated by the Engineer.

2.3.1.2 NATURE of EXCAVATION:

2.3.1.2.1 Unclassified Excavation – Unclassified excavation shall consist of

the excavation and disposal of all materials regardless of its nature, or

not classified and included in the Bill of Quantities under other pay

items.


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2.3.1.2.2 Common Excavation – Common excavation are those not included

in the Bill of Quantities under “Rock Excavation” or other pay items.

2.3.1.2.3 Muck Excavation – Muck Excavation shall consist of the removal

and disposal of deposits of saturated of unsaturated mixtures of soils

and organic matter not suitable for foundation materials regardless ofmoisture content.

2.3.2 EXECUTION

Before commencement of excavation, spot levels on an approved grid covering

the entire plot shall be taken by the Contractor in consultation with the

Engineer and a proper record of these levels shall be kept jointly signed by the

Contractor and the Engineer. A block level plan showing all ground levels of the

plot shall be prepared by Contractor and shall also be jointly signed by the

Contractor and the Engineer.

Excavation shall include removal of all materials of whatever nature at all

depths and whether wet or dry necessary for the construction of foundation

exactly in accordance with lines, levels, grades and curves shown in the Plans

or as directed by the Engineer. The bottoms of excavation shall be leveled both

longitudinal and transversely or sloped as directed by the Engineer.

Should the contractor excavate to a greater depth or width than shown on the

Plans or as directed by the Engineer, he shall at his own expense fill the extra

depth or width in cement concrete in proportion as to be directed by the

Engineer. The Contractor shall report to the Engineer when the excavations areready to receive concrete. No concrete shall be placed in foundations until the

Contractor has obtained the Engineer’s approval. In case, the excavation is

done through different types of soil and if different rates are applicable as per

provision in the Bill of Quantities, the Contractor must get the dimensions of

the strata agreed by the Engineer for payment. If no specific provisions is made

in the Bill of Quantities it will be presumed that excavation shall be in all types

of soil and the contractor's rate hall cover for the same.

When there is evidence of discrepancy between the actual elevations and those

shown in the plans, a pre-construction survey shall be conducted by the

Contractor under the control of the Engineer to serve as the basis for the

computation of the actual volume of excavated materials. All excavation shall

be finished to a reasonably smooth and even surface. Excavation operation

shall be carried out with outmost care ensuring that foundations below

existing parts of structure shall not be disturbed.

If instructed by the Engineer all foundation pits, and similar excavations shall

be strongly fenced and marked with red lights at night to avoid accidents.

Adequate protective measure shall be taken to make sure that the excavation

does not affect or damage adjoining structures. All measures required for the

safety of excavations, the people working in and around the foundation

trenches, property and the people in the vicinity shall be taken by the

Contractor at his own cost. He shall be entirely responsible for any injury and

damage to property caused by his negligence or accident due to his

constructional operations, storage of materials etc. Should there be

disturbance of foundations below existing structures same shall be repaired


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and restored in a manner acceptable to the Engineer at no additional cost or

compensation.

2.3.2.1 SHORING

The sides of the excavations should be timbered or supported in such a

way as is necessary to secure these from falling in, and the shoring shall

be maintained in position as long as necessary. The Contractor shall be

responsible for the proper design of the shoring to be approved by the

Engineer to hold the sides of the excavation in position and ensure safety

of persons and properties. The shoring shall be removed as directed after

the items for which it is required are completed. Unless otherwise

mentioned in the Bill of Quantities no extra payment will be made for

shoring.

2.3.2.2 STACKING OF EXCAVATED MATERIALS

Materials suitable and useful for back filling, plinth filling or levelling of

the plot or other use shall be stacked in convenient places but not in such

a way as to obstruct free movement of men, animals and vehicles or

encroach on the area required for constructional purposes.

2.3.2.3 BACKFILLING

All shoring and form work shall be removed after their necessity ceases

and trash of any sorts shall be cleaned out from the excavation. All space

between foundation masonry or concrete and sides of excavation shall be

refilled to the original surface with approved excavated materials in layers

fifteen (15) centimeter in thickness watered and rammed. The filling shall

be done after concrete or masonry is fully set and done in such a way as

not to cause undue thrust on any part of the structure. Where suitable

excavated materials is to be used for refilling it shall be brought from the

place where it is temporarily stacked and used in refilling.

No excavation of foundations shall be filled in or covered up until all

measurements of excavations, masonry concrete and other works below

ground level are jointly recorded. Black cotton soil shall not be used for

back filling or in plinth filling.

2.3.2.4 DEWATERING

Excavation shall include bailing or pumping out water which may

accumulate in the excavation during the progress of work either from

seepage, springs, rain or any other cause and diverting surface flow if any

by bunds or other means. Pumping out of water shall be done in such

approved manner as to preclude the possibility of any damage to the

foundation trench concrete or masonry or any adjacent structure. When

water is met in foundation trenches or in tank excavations, pumping out

water shall be carried out from auxiliary pit of adequate size dug slightly

outside the excavations. The depth of auxiliary pit shall be more than the

working foundation trench levels. The auxiliary pit shall be refilled with

approved excavated materials after the dewatering is over. The excavation

shall be kept free from water:


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a. during inspection and measurement

b. When concrete / masonry works are in progress and till they come

above the natural water level and

c. Till the Engineer consider that the concrete/mortar is sufficiently set

2.3.2.5 SURPLUS EXCAVATED MATERIALS

All excavated materials certified as surplus and not useful shall be

removed by the Contractor from the site in an approved manner with the

approval of the Local Authority as required to his own dump and shall be

paid as a separate item as in the Bill of Quantities. No extra claim on any

account will be paid. The items of removal of surplus excavated materials

shall only be undertaken by the Contractor when specific instruction in

this regard has been obtained from the Engineer. The Contractor must also

secure the approval of the Engineer regarding the quantity of surplusmaterials to be removed prior to commencement of this item of work.


The volume of excavation to be paid for will be the number of cubic meter

measure in the original position of material acceptably excavated in conformity

with the plans or as directed by the Engineer.

The accepted quantities, measured as prescribed above shall be paid for the

contract unit price for each of the particular pay items listed and included in

the Bill of Quantities. The payment shall constitute full compensation for theremoval and disposal of excavated materials including all labor, equipment

tools and incidentals necessary to complete the work prescribed in this item.

ITEM 2.4 ROCK EXCAVATION

2.4.1 GENERAL

2.4.1.1 DESCRIPTION

This item shall consist of the necessary rock excavation for foundations

and other structures indicated in the Plans, in accordance to these

specifications and in conformity with the lines, grades and dimensions

shown in the plans of as indicated and established by the Engineer. The

Contractor shall be aware of obstructions such as pipes, conduits andcables in the areas to be excavated. The Contractor shall verify the

existence and location of such obstructions before the start of excavation.

All excavated materials shall be disposed properly and deposited at

locations indicated by the Engineer.

2.4.1.2 Nature of Excavation:


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Rock excavation shall consist of igneous, sedimentary and metamorphic

rock which cannot be excavated without blasting or the use of rippers, and

all boulders or other detached stones each having a volume of 1 cubic

meter or more as determined by physical measurements or visually by the

Engineer.

2.4.2 EXECUTION

Before commencement of excavation spot levels on an approved grid covering

the entire plot shall be taken by the Contractor in consultation with the

Engineer and a proper record of these levels shall be kept jointly signed by the

Contractor and the Engineer. A block level plan showing all ground levels of the

plot shall be prepared by Contractor and shall also be jointly signed by the

Contractor and the Engineer.

When there is evidence of discrepancy between the actual elevations and those

shown in the plans, a pre-construction survey shall be conducted by the

Contractor under the control of the Engineer to serve as the basis for the

computation of the actual volume of excavated materials. All excavation shall

be finished to a reasonably smooth and even surface. Excavation operation

shall be carried out with outmost care ensuring that foundations below

existing parts of structure shall not be disturbed.

If instructed by the Engineer all foundation pits, and similar excavations shall

be strongly fenced and marked with red lights at night to avoid accidents.

Adequate protective measure shall be taken to make sure that the excavation

does not affect or damage adjoining structures. All measures required for the

safety of excavations, the people working in & around the foundation trenches,

property and the people in the vicinity shall be taken by the Contractor at his

own cost. He shall be entirely responsible for any injury and damage to

property caused by his negligence or accident due to his constructional

operations, storage of materials etc. Should there be disturbance of

foundations below existing structures same shall be repaired and restored in a

manner acceptable to the Engineer at no additional cost or compensation.

2.4.2.1 BLASTING

The transportation, handling, storage, and use of dynamite and other

explosives shall be directed and supervised by a personnel of proven

experience and ability who is authorized and qualified to conduct blasting

operations.

Blasting shall be done in a manner as to prevent damage to the work or

unnecessary fracturing of the underlying rock materials and shall conform

to any special requirements specified. When specified, the contractor shall

furnish the Engineer, in writing, a blasting plan before blasting operations

begin.

2.4.2.2 USE OF EXCAVATED ROCK MATERIALS

Suitable material from the specified excavations may be used in the

construction of required rock fill. The suitability of material for specific

purposes is determined by the Engineer.


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2.4.2.3 DISPOSAL OF WASTE MATERIALS

All surplus or unsuitable excavated materials are designated as waste and

shall be disposed of by the Contractor at sites of his own choosing away

from the site of the work. The disposal shall be in an environmentally

acceptable manner that does not violate local and national rules andregulations.

2.4.2.4 EXCAVATION LIMITS

Excavations shall comply with Department Order No. 13 – 1998 otherwise

known as Guidelines Governing Occupational Safety and Health in the

Construction Industry. All excavations shall be completed and maintained

in a safe and stable condition throughout the total construction phase.

Structure and trench excavations shall be completed to the specified

elevations and to the length and width required to safely install, adjust,

and remove any forms, bracing, or supports necessary for the installation

of the work. Excavations outside the lines and limits shown on the Plans

or specified herein required to meet safety requirements shall be the

responsibility of the Contractor in constructing and maintaining a safe and

stable excavation.

2.4.3 MEASUREMENT/METHOD OF PAYMENT

The volume of excavation to be paid for will be the number of cubic meter

measure in the original position of material acceptably excavated in

conformity with the plans or as directed by the Engineer.

The accepted quantities, measured as prescribed above shall be paid for

the contract unit price for each of the particular pay items listed and

included in the Bill of Quantities. The payment shall constitute full

compensation for the removal and disposal of excavated materials

including all labor, equipment tools and incidentals necessary to complete

the work prescribed in this item.

ITEM 2.5 HAULING OF MATERIALS

2.5.1 GENERAL

2.5.1.1 DESCRIPTION

This item shall consist of hauling of materials specified in the Bill of

Materials needed for the project. These are aggregates, cement, reinforcing

bars, lumbers, formwork sand and other materials needed for the

completion of the project.

2.5.2 EXECUTION

The Contractor shall be responsible for monitoring truck weight regulations or

the maximum allowable loads for various axle configurations on roadways

outside the project limits and on roadways within the project limits open to

general traffic. All hauling units delivering equipment or materials to the

project shall be of legal weight loads and/or have appropriate hauling permits.


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The volume or amount of materials to be hauled to the project location of the

project will conform to the amount of materials required for the project as

specified on the Bill of Materials.


The Contractor will be paid as per accomplishment of the project.

ITEM 2.6 ANCHORING 20MM Ø RSB

2.6.1 GENERAL

2.6.1.1 DESCRIPTION

This work shall consist of the installation of rock dowels at the locations

and orientations designated in the Plans or by the Engineer. The

Contractor shall select and construct the dowels and supply all materials,

equipment, and labor to test and install the dowels. The Engineer will

designate the orientation and minimum length of the dowel required.

2.6.2 SUBMITTALS

Not less than two weeks prior to commencing the rock doweling, the Contractor

shall submit in writing to the Engineer for approval:

The Contractor shall provide written evidence that the foreman and drill

operator have performed satisfactory work in similar capacities elsewhere. The

drill operator assisted by the foreman shall have installed rock dowels as

indicated in the Plan.

The Contractor shall submit a detailed plan for the rock doweling to include:

a.The proposed construction sequence and schedule.

b.The proposed drilling method and equipment.

c.The proposed drill hole diameter.

d.The proposed cement grout mix design

e.The proposed construction method for upwardly inclined anchors.

f.The proposed corrosion protection for the rock dowel system.

g.The calibration data for each load cell, test jack, pressure gauge and

master pressure gauge to be used in the proof testing.

h.The proposed stressing procedures and stressing equipment to proof test

the dowels.

Work shall not begin until the Engineer has approved the appropriate

submittals in writing.

2.6.3 MATERIAL REQUIREMENTS

All rock dowels, including anchorage, bearing plates, couplers, corrosion

protection, and other appurtenances, shall be products of a manufacturer


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regularly engaged in the manufacturing of materials for the construction of

rock dowels.

Dowels shall be fabricated from deformed steel bars in general compliance with

DPWH Standard Specification. Anchor bar steel shall not be precut at the

factory to lengths shown in the Plans, but rather be delivered in bulk lengthsand field cut to the appropriate length. Anchor bar steel shall be provided with

either fusion-bonded epoxy coating or hot dip galvanizing for corrosion

protection. Epoxy coating shall be applied in accordance with ASTM A.

Extreme care shall be taken in the handling of epoxy-coated bars to prevent

coating damage and embrittlement. Field handling procedures for epoxy-

coated bars shall be in general accordance with ASTM D 3963 including

providing padding between contact points during storage and lifting and

covering coated bars to minimize ultraviolet exposure. Hot dip galvanizing

shall comply with ASTM A 15.

Each rock dowel shall be fitted with a bearing plate and nut. The plate shall

have a central hole large enough to fit easily over the dowel while maximizing

the average bearing surface for the washer and the nut. Spherical seating of

the nut is not required. Beveled washers shall be used to accommodate non-

perpendicular installations.

Cement grout shall be a proven, non-shrink material capable of permanently

developing the bond and internal strength necessary for the required dowel

capacity. The use of epoxy or polyester resin as bonding agents is not allowed.

If requested by the Engineer, a sample of the cement grout shall be provided fortesting.

2.6.4 EXECUTION

Work shall proceed according to the plan and schedule submitted by the

Contractor prior to the commencement of the work.

The Engineer shall specify the location, orientation, and minimum length of

each rock dowel. The rock dowel shall be installed within five degrees of the

specified angle. Unless otherwise specified, the angle of installation shall be

perpendicular to the rock face and inclined slightly downward. If the axis of

the rock dowel is not close to perpendicular to the rock face or within the angle

provided by the beveled washer, or the rock beneath the bearing plate is not

sound, a bearing pad approved by the Engineer shall be constructed at no

additional cost, so that the rock dowel is not bent when tensioned. In all

cases, at least three quarters of the bearing plate shall be in contact with the

rock face.

The dowels shall be handled and stored in such a manner as to avoid damage

or corrosion of the coating and the steel. Damage to the dowel steel as a result

of abrasion, cuts, nicks, welds, and weld splatter will be cause for rejection.

The dowels shall be protected from dirt, rust, and harmful substances. If

heavy corrosion or pitting is noted, the Engineer will reject the rock dowel.

The entire length of the rock dowel shall be encapsulated in cement grout for a

second level of corrosion protection. All exposed parts of the dowel, bearing

plate and nut on the surface shall be painted with approved corrosion

protection paint or epoxy patching compound.


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The use of hand drills for advancing the anchor hole is not allowed without

written permission by the Engineer and demonstrated effectiveness by the

Contractor.

The drill hole shall be sized to provide a minimum of 50 millimeter of grout

cover around the bar. The Contractor shall flush the drill hole of all drillcuttings and debris with compressed air prior to the installation of the rock

dowel. Holes drilled for rock dowels in which dowel installation is considered

by the Engineer to be impractical shall be re-drilled at the Contractor’s

expense.

The grout equipment shall produce a grout free of lumps and undispersed

cement. The pump shall be equipped with a pressure gauge near the discharge

end to monitor grout pressures. The grouting equipment shall be sized to

enable the grout to be pumped in one continuous operation. The grout shall

be injected from the lowest point of the drill hole. The quantity of the groutand the grout pressures shall be recorded.

When the cement grout has reached final set, the Contractor shall install the

bearing plate, washers and nut. The end of the completed rock dowel shall be

trimmed to within 15 centimeters of the rock face.

At the discretion of the Engineer, up to 5 percent, but not less than three rock

dowels, of the installed rock dowels shall be proof tested. The Contractor shall

conduct the proof test, and the Engineer will interpret the results. The rock

dowel shall be tensioned to 11, 500 kilograms with a calibrated hollow-ram

hydraulic jack using a bar extension and coupler attached to the rock dowel

and held for 10 minutes. If no loss of load occurs over this time period, the

rock dowel is acceptable. The Engineer may require additional proof of testing

beyond the 5 percent maximum, if rock dowels fail the proof testing. All failed

rock dowels shall be replaced with an additional rock dowel installed in a

separate hole. No payment will be made for rock dowels that fail or for

additional proof testing.


Rock dowels will be measured per linear meter of rock dowel installed and

accepted.

The accepted quantity shall be paid for at the contract unit price and payment

shall be full compensation for furnishing and placing all materials, including

all labor, equipment, tools and incidentals necessary to complete the work

prescribed in this item.

ITEM 2.7 STONE MASONRY

2.7.1 GENERAL

2.7.1.1 DESCRIPTION

This item shall consist of stone masonry in minor structures, in headwalls,

for culverts, in retaining walls at the toes of slopes, and other places called

for on the plans, constructed on the prepared foundation bed in


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accordance with this Specifications and in conformity with the lines,

grades, sections, and dimensions shown in the plans or as ordered in

writing by the Engineer. It shall include all management, labor,

transportation, materials, tools, equipment and services required to

manufacture, assemble, deliver, and install all items necessary for the

proper execution and completion of said items of work.


2.7.2.1 STONE

The stone shall be clean, hard and durable and shall be subjected to the

Engineer’s approval. Adobe stone shall not be used unless otherwise

specified.

Sizes and Shaped. Unless other sizes are shown on the plans, stones shall

have a thickness of not less than one and one half times their respectivethickness, and lengths of not less than one and one half times their

respective widths.

Dressing. The stone shall be dressed to remove any thin or weak portions.

Face stones shall be dressed to provide bed and joint lines that do not vary

more than twenty (20) millimeters from corners of the stones in excess

thirty (30) millimeters in radius. Bed surfaces of the face stones shall be

approximately normal to the face of the stones for about eighty (80)

millimeters and from this point may depart from a normal plane not to

exceed fifty (50) millimeters in three hundred (300) millimeters.

Finish for exposed Faces – Face stones shall be pitched to line along the

beds and joints. The maximum projection of rock faces beyond the pitch

lines shall not be more than fifty (50) meters.

2.7.2.2 MORTAR

Cement, fine aggregate, and water shall conform to the respective

requirements for those materials as specified under structural concrete,

except to the grading of the aggregate which shall all pass the two and

thirty six hundredths (2.36) millimeters (No. 8) sieve, not less than fifteen

(15) percent nor more than forty (40) percent shall pass the three tenths

(0.3) millimeters (No. 50) sieve, and not more than ten (10) percent shall

pass the fifteen hundredths (0.15) millimeters (No. 100) sieve.

2.7.3 EXECUTION

2.7.3.1 SELECTION AND PLACING

When the masonry is to be placed on a prepared foundation bed, the bed

shall be firm and normal to, the face of the wall, and shall have been

approved by the Engineer before any stone is placed.

All stones shall be cleaned thoroughly and wetted immediately before being

set and the bed which is to receive them shall be cleaned and moistened

before the mortar spread. They shall be laid with their longest faces

horizontal in full beds of mortar. The stones shall be handled as not jar or

displace the stones already settled.


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Suitable equipment shall be provided for setting stones larger than those

that can be handled by two men. The rolling or turning of stones on the

walls will not be permitted. If a stone is loosened after the mortar has

taken initial set, it shall be removed, the mortar cleaned off, and the stone

is loosened after the mortar has taken initial set, it shall be removed, the

mortar cleaned off, and the stone re – laid with fresh mortar.

2.7.3.2 CURING

If hot or dry weather, the masonry shall be satisfactory protected from the

sun and shall be kept wet for a period of at least three days after

completion.


The quantity to be paid for shall be the number of cubic meters of stone

masonry complete in place and accepted. Projections extending beyond thefaces of the walls shall not be included. In computing the quantity for payment,

the dimension used shall be those shown on the plans or ordered in writing by

the Engineer. No deductions shall be made for weep holes drain pipes or other

openings of less than one square meter in area.

The quantity of masonry, determined as provided, shall be paid for at the

contract unit price per cubic meter for stone masonry, which price and

payment shall be full compensation for furnishing and placing all materials,

including mortar for masonry, for all necessary excavation, and for all labor,

equipment, tools and incidentals necessary to complete the item.

ITEM 2.8 REINFORCING BARS GRADE 40

2.8.1 GENERAL

2.8.1.1 DESCRIPTION

This item shall consist of furnishing, bending, fabricating and placing of

steel reinforcement of the type, size, shape, and grade required in

accordance with this specification and in conformity with the requirementsshown on the plans or as directed by the Engineer.

2.8.2 SUBMITTALS

A copy of list of all reinforcing steel and bending diagrams shall be furnished to

the Engineer at the site of the work at least one week before the placing of

reinforcing steel is begun.

The Contractor shall be responsible for the accuracy of the lists and for

furnishing and placing all reinforcing steel in accordance with the details

shown on the plans.


Unless otherwise designated on the plans, or herein, all reinforcing steel shall

conform to the requirements of the following specifications:

Table 2.8.3: STEEL SPECIFICATION


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Deformed Billet - Steel Bars for Concrete

Reinforcement

ASTM A 615

AASHTO M 31

Deformed Steel Wire for Concrete Reinforcement ASTM A 496

AASHTO M 225

Welded Steel Wire Fabric for Concrete

Reinforcement

ASTM A 185

AASHTO M 55

Cold - Drawn Steel Wire for Concrete

Reinforcement

ASTM A 82

AASHTO M 32

Fabricated Steel Bar of Rod Mats for Concrete

Reinforcement

ASTM A 184

AASHTO M 54

Welded Deformed Steel Wire Fabric of Concrete

Reinforcement

ASTM A 497

AASHTO M 221

Plastic Coated Dowel Bars Type A

AASHTO M 254

Loy Alloy Steel Deformed Bars for Concrete

Reinforcement ASTM A 206

Bar reinforcement for concrete structures, except No. 2 bars shall be deformed

in accordance with AASHTO M 42, M31 and M53.

Dowel and tie bars shall conform to the requirements of AASHTO M31 or

AASHTO M42 except that rail steel should not be used for tie bars that are to

be bent and re-straightened during construction. Tie bars shall be free from

burring of other deformation restricting slippage in the concrete. A minimum of

one half (

1

2 ¿ the length of each dowel bar shall be painted with one coat of

approved lead of tar paint before delivery to the site of the work.

The sleeves for dowel bars shall be metal of an approved design to cover fifty

(50) millimeters (2 inches), plus or minus six and three tenths (6.3) millimeters

of the dowel, with a closed end, and with suitable stop to hold the end of the

sleeve at least twenty five (25) millimeters (1 inch) from the end of the dowel

bar. Sleeves shall be of such design that they do not collapse during

construction.

Plastic coated dowel bar conforming to AASHTO M 254 may be used.

2.8.4 EXECUTION

2.8.4.1 ORDER LIST

Before materials are ordered, all order lists and bending diagrams shall be

furnished by the Contractor, for approval of the Engineer. The approval or

order lists and bending diagrams by the Engineer shall in no way relieve

the Contractor of responsibility for the correctness of such lists and

diagrams. Any expenses incident to the revisions of materials furnished

with the plans shall be borne by the Contractor.

Bar lists and bending diagrams for structures, which are included on the

Plans, do not have to be furnished by Contractor. When bar lists and

bending diagrams are included on the Plans, they are intended for

estimating approximate quantities. Contractor shall verify the quantity,


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size, and shape of the bar reinforcement against those shown on the Plans

and make any necessary corrections before ordering.

2.8.4.2 PROTECTION OF MATERIALS

Steel reinforcement shall be stored above the surface of the ground upon

platforms, skids, or other supports and shall be protected as far as

practicable from mechanical injury and surface deterioration caused by

exposure to conditions producing rust. When placed in the work

reinforcement shall be free from dirt, detrimental rust, loose scale, paint,

grease, oil or other foreign materials. Reinforcement shall be free from

injuries effects such as cracks and laminations. Rust, surface scars,

surface irregularities of mill scale will not be caused for rejection, provided

the minimum dimensions are demonstrated.

2.8.4.3 BENDING

All reinforcing bars shall be bent cold except as shown on the Plans or as

permitted by the Engineer. Bars shall not be bent or straightened in a

manner that will cause damage to the bars. Irregularities in the bars shall

be caused for the rejection. Bars shall be bent around a circular pin having

the following diameter (d b) in relation to the diameter of the bar (d):

Nominal Diameter (d), mm Pin Diameter (d b)

10 to 20 6d

25 - 28 8d

32 and greater 10d

Bends and hooks in stirrups or ties may be bent to the diameter of the

principal bar enclosed therein.

2.8.4.4 PLACING AND FASTENING

The reinforcing bars shall be free from dirt, loose mill scale, paint, oil,

loose rust, or other foreign substance.

Steel reinforcement shall be accurately placed in the positions shown on

the plans or as required by the Engineer and firmly held at all intersectionduring the placing and setting of concrete except where spacing is less

than three hundred (300) millimeters in each direction, in which case,

alternate intersections shall be tied. Ties shall be fastened on the inside.

Distance from the forms shall be maintained by means of stays, blocks,

ties, hangers, or other approved supports, so that it does not vary from the

position indicated on the plans by more than six (6) millimeters. Blocks for

holding reinforcement from contact with the forms shall be precast mortar

blocks of approved shapes and dimensions. Layers of bars shall be

separated by precast mortar blocks or by other equally suitable devices.

The use of pebbles, pieces of broken stone or brick, metal pipe and wooden

blocks shall not be permitted. Unless otherwise shown in the plans or

required by the Engineer, the minimum distance between bars shall be

forty (40) millimeters. Reinforcement in any member shall be placed and

concrete begins. Concrete placed in violation of this provision may be

rejected and removal may be required. If fabric reinforcement is shipped in


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rolls, it shall be straightened before being placed. Bundled bars shall be

tied together at not more than one and eight tenths (1.8) meters interval.

2.8.4.5 SPLICING

All reinforcement shall be furnished in the full lengths indicated on the

plans. Splices of reinforcement shall be made only at locations shown on

the Plans and provided by the steel schedule unless accepted by the

Engineer. Splices shall be staggered as far as possible. Except otherwise

indicated, splicing of reinforcement shall be in accordance with American

Concrete Institute (ACI) – 318M, except that the minimum separation shall

not be less than forty (40) bar diameter.In cases where permission is

granted to splice bars, other than those shown on the plans, the additional

material required for the lap shall be furnished by Contractor at his’ own

expense. All splices shall be full contact splices.

Unless otherwise shown on the plans, bars shall be lapped a minimum

distance of:

Splice TypeGrade 40 Min.

Lap

Grade 60 Min.

Lap

But not less

than

Tension 24 bar diam. 36 bar diam. 300 mm

Compression 20 bar diam. 24 bar diam. 300 mm

In lapped splices, the bars shall be placed in contact and wired together.

Lapped splices will not be permitted at locations where the concrete

sections is sufficient to provide minimum clear distance of one and one –

third the maximum size of coarse aggregate between the splice and the

nearest adjacent bar. Welding of reinforcing steel shall be done only if

detailed on the plans or if authorized by the Engineer in writing. Spiral

reinforcement shall be spliced by lapping at least one and a half turns or

by butt welding unless otherwise shown on the plans.

2.8.4.6 WELDING OF SPLICES

Where shown on the plans or required by the provisions of this item,

welded bar splices shall be used. All splices whether lap, weld, mechanicalor coupler, shall develop the full strength of the bar. Information on

mechanical splicing devices and couplers shall be submitted for approval

prior to use.

2.8.4.7 LAPPING OF BAR MAT

Sheets of mesh or bar mat reinforcement shall overlap each other

sufficiently to maintain a uniform strength and shall be security fastened

at the ends and edges. The overlap shall not be less than one mesh in

width.


The quantity of reinforcing steel to be paid for will be the final quantity placed

and accepted in the completed structure.

No allowance will be made for tie-wires, separators, wire and other materials

used in fastening the reinforcing steel in place. If bars are substituted upon the


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Contractor’s request and approved by the Engineer and as a result thereof

more steel is used than specified shall be measured for payment.

No measurement or payment will be made of splices added by the Contractor

for his convenience. When there is no item for reinforcing steel in the Bill of

Quantities, costs will be considered as incidental to the other item in the Bill ofQuantities.

The accepted quantity, measured as Bill of Quantities shall be paid for at the

contract unit price for reinforcing steel which price and payment shall be full

compensation for furnishing and placing all materials, including all labor,

equipment, tools and incidentals necessary to complete the work prescribed in

this item.

ITEM 2.9 FORMS/ DEFORM WORKS

2.9.1 GENERAL

This item specifies the requirements for the design, construction and removal

of formwork required to produce the finished concrete to the shape, lines and

dimensions shown on the Plans.

2.9.1.1 DESCRIPTION

Formwork shall be meticulously checked of all recognized line and grade

references so that the final structure is within the limits of the specified

dimensional tolerances. They shall be designed to withstand the worst

combination of self-weight, live load, rate of placement, height of drop,

weight of moving equipment, together with all incidental dynamic effects

caused by placing, vibrating and compacting the concrete. The Contractor

shall verify that reinforcement is free of loose scale or rust and

contaminants and shall be fabricated in accordance with fabrication

herein specified and/or in the Plans. Reinforcement shall be checked of its

allowable tolerances and splicing requirements, and shall be kept in its

proper position during placement of concrete. The Contractor shall also

check that all samples and certificates are submitted and approved. Allitems to be embedded in concrete shall be complete and in their proper

position. Partially set concrete shall not be reworked and used. Vibrators

shall not be used excessively and to transport concrete. Concrete flatwork

shall be struck level and floated to disappearance of water sheen and shall

be finished as specified. Concrete shall be cured as indicated and shall be

protected from flowing water shock or excessive vibration during curing.


The type and condition of formwork sheeting and lining, and the ability of the

formwork and its supports to withstand distortion caused by the placementand compaction of the concrete, and the standard of workmanship used in the

formwork construction shall be such that the finished surfaces of the concrete

will conform to the requirements of the specifications and Plans.

Form lumber shall be stress graded or merchantable and shall be of non –

staining species and dressed on concrete forming side if to be used for exposed


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Formwork panels shall be supplied in the maximum practicable width and

length to minimize the number of joints.

Plywood panels shall be placed with the grain of the outer plies in the direction

of the span.

Form oil, or coating shall be non – staining, compatible with subsequent

finishing and bonding, and shall be effective in sealing wood from moisture.

2.9.3 EXECUTION

2.9.3.1 FORMWORK DESIGN

Formwork shall be rigid, watertight, braced and tied together so as to

maintain position and shape during all construction activities, and shall

be constructed in such a way that it can be removed without damage to

the concrete. Where formwork is to be re-used, the formwork design shall

allow for the deterioration of materials through use and handling. Where

formwork requires design, the Contractor shall submit to the Engineer for

review of its detailed Plans and specifications of the proposed formwork not

less than two weeks prior to the commencement of formwork construction.

The formwork design shall be verified in accordance with the Contract to

confirm that design satisfies the performance requirements of the

formwork. Any amendment to the design shall be referred to the Engineer

for review and final decision. The formwork Plans shall include all details

of formwork, formwork joints, sealing procedures, ties, size and spacing of

framing and details of any proprietary fittings or systems proposed to be

used. Where vibration is to be applied externally, the design of formwork

shall include details of external vibrators to ensure efficient compaction

and to avoid surface blemishes.

2.9.3.2 FORM CONSTRUCTION

Formwork shall be constructed and shall be of sufficient stiffness to

tolerate high frequency vibration and shall be of uniform stiffness to avoid

causing varying vibration amplitudes over the formwork surfaces during

compaction of the concrete. The constructed formwork shall maintain

correct position and shape and achieve the specified dimensions, levels

and geometry of the finished structural component. The use of wires or

bolts extended to the surface of the concrete will not be permitted except

where shown on the Plans. Any embedded ties shall remain embedded and

shall terminate not less than the minimum clear cover specified on the

Plans. All recesses shall be filled with a shrinkage compensating

cementitious mortar.

Errors in line or level of the formwork, or positioning and/or quantity of

steel reinforcement shall be corrected prior to placing concrete. The

Contractor will be responsible for any defects to the formwork,

reinforcement, embedded components, or the formed concrete surface,

which may become apparent during or after casting the concrete.

Formwork shall not be placed in locations where steel reinforcement and

other fixtures cannot be inspected, until such time that the evidence that


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the reinforcement and other fixtures conform to the requirements of the

specifications and the Plans has been obtained and recorded by the

Contractor.

Fillets and chamfers shall be provided at re-entrant angles and corners.

The interior surface of formwork shall be thoroughly cleaned out andtreated with form oil or lubricant to prevent adhesion of the exposed

concrete surface. The form oil or lubricant shall be of the non-staining type

and shall not discolor the surface of the concrete. The oil or lubricant shall

be applied uniformly in a thin film and any surplus removed prior the

concrete placement. Reinforcement and other embedment shall not be

soiled by the form oil or lubricant.

Prior to commencement of the concreting operations all tie wire ends, wood

chips and other debris shall be removed from the forms. Formwork shall

be sufficiently tight at joints to prevent loss of slurry or mortar while theconcrete is in its freshly placed state, consistent with the method of

placement and compaction. Formwork shall also be mortar tight where

holes are needed to facilitate projecting reinforcement or fixing devices.

2.9.3.3 REMOVAL OF FORMS

Formwork shall be so constructed as to allow for its undisturbed

dismantling and removal from the cast concrete without shock or damage.

Shock or damage to the cast concrete shall also be prevented when

removing formwork in the vicinity of projecting reinforcement or fixing

devices. Side forms for beams, girders and walls three feet or less may be

removed as directed by the Engineer earlier than otherwise specified.

Time of removal of forms shall be as follows:

a. Joints, beams and girder soffits.

- Clear span less than three (3) meters – seven (7) days

- Clear span three (3) meters to six (6) meters – fourteen (14)

days

- Clear span over six (6) meters – twenty one (21) days.

b. Slabs

- Clear span six (6) meters – seven (7) days

- Clear span over six (6) meters – fourteen (14) days

Formwork tolerance for cast – in – place concrete form plumb shall be as

follows:

a. Lines and surfaces of columns, piers, walls and arises one (1)

centimeter per three and five hundredths (3.05) meters but not morethan three (3) centimeters.

b. Exposed corner columns, control joints, grooves and all

conspicuous lines:

- In any bay – one half (½) centimeters


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- Distances up to six (6) meters – one half (½) centimeters

- Distances up to twelve (12) meters – one (1) centimeters

Shoring

All trenches and other excavations shall be properly sheeted and braced, to furnish working conditions acceptable to the Engineer.

Bracing shall be so arranged as not to place any strains on portions of

completed work until the general construction has proceeded far

enough to provide ample strength in the opinion of the Engineer.


The quantities measured as arranged above shall be paid for at the contract

unit price of the pay item that is contained within the Bill of Quantities.

Payment shall be the reimbursement for all materials, labor, equipment, tools,

and incidentals necessary to complete the work prescribed in this item.

ITEM 2.10 CONCRETING WORKS (3500 PSI)

2.10.1 GENERAL

Concrete shall be composed of Portland cement, fine aggregate, coarse

aggregate, water and admixtures as specified for the work except as otherwise

authorized in writing by the Engineer. Ready mix concrete shall be permitted,

provided it can be placed within the time requirements specified and complies with all of the provisions hereinafter specified.

2.10.1.1 DESCRIPTION

This item shall consist of furnishing, placing, and finishing concrete in

concrete/ reinforced concrete structures in accordance with this

specification and conforming to the lines, grades, and dimension shown on

the plans.

a. All reinforced concrete horizontal, vertical construction and expansion

joints shall be provided with rubber water stop dumbbell type.

b. Concrete for foundation, beams, columns, weir and desander shall

have the strength of at least 3500 psi.

c. Unless indicated all structures not exposed to water shall have a

comprehensive strength of at least 3000 psi.

2.10.2 SUBMITTALS

Samples of constituent materials and of concrete as placed shall be subjected

to laboratory tests. The Contractor shall submit samples of materials as

directed by the Engineer for his approval and all materials incorporated shallconform to the approved samples. The Contractor shall design the concrete

mixes for all classes of concrete as will be define in this specification and

submit his proposal together with the test results of the strength of all classes

of the concrete mix design for the approval of the Engineer. The design of the

concrete mixes and the concrete strength test shall be made in the field


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laboratory in the presence of the Engineer or his representative. The

Contractor is responsible for all expenses incurred in this process.

The use of ready-mixed concrete in any part of the work shall require the

Engineer’s written approval. The Contractor shall satisfy the Engineer’s plan as

to the sampling, trial mixing, testing and quality of concrete of various gradesshall equally applied to ready-mixed concrete, which shall be made and

delivered. Every additional facility including transport, which the Engineer or

persons authorized by him may require for the supervision and inspection of

batching, mixing and transporting to site of ready-mixed concrete shall be

provided by the Contractor at no extra cost to the client. Prior to any major

concreting as instructed by the Engineer, the Contractor shall submit a

method statement furnishing all the relevant details including the plants he

intends to use for the approval of the Engineer.


2.10.3.1 PORTLAND CEMENT

The cement used for any particular mixed shall comply with the following

cited specification for the type specified or permitted.

TYPE SPECIFICATION

Portland Cement AASHTO M 85 (ASTM C 150)

Blended Hydraulic Cements AASHTO M 240 (ASTM 595)

Masonry Cement AASHTO M 150 (ASTM C91)

When types IV and V (AASHTO M 85), P and PA (AASHTO M 150) cements

are used, proper recognition shall be given to the effects of slower strength

gain on concrete proportioning and construction practices. Types S and

SA cements will be permitted only when blended with Portland cement in

proportions approved only by the Engineer.

Unless otherwise permitted by the Engineer, the product of only one mill

of any brand and type of Portland cement shall be used on the project.

The cement shall be in bags sealed with the manufacturer’s seal. The

storage shall be maintain in a perfectly dry and well ventilated condition

above ground level or as per instructions issued by the Engineer. Any

cement which has been deteriorated or caked or which has been damageddue to any reason whatsoever shall not be used. Should the results of any

laboratory tests show that any samples does not comply with the specified

requirement, the whole consignment from which the sample was taken,

shall be rejected and replaced with cement of satisfactory quality all

shouldered by the Contractor. Any work carried out with the failed cement


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shall also be dismantled or corrective action taken by the Contractor as

per instructions of the Engineer.

2.10.3.2 CONCRETE AGGREGATE

2.10.3.2.1 FINE AGGREGATES

Sand or fine aggregate shall be comprise of natural sand, washed

and sieved to remove particles larger than five (5) millimeters. It can

be stone screenings or other inert materials with similar

characteristics, or combination thereof, having hard, strong and

durable particles approved by the Engineer. Fine aggregate from

different sources of supply shall not be mixed or stored in the same

pile nor used alternately in the same class of concrete without the

approval of the Engineer.

Fine aggregate shall not contain more than three (3) mass percent ofmaterial passing the seventy five hundredths (0.75) millimeters (No.

200) sieve by washing nor more than one (1) mass percent each of

clay lumps or shale. The use of beach sand will not be allowed

without the approval of the Engineer.

If the fine aggregate is subjected to five (5) cycles of the sodium

sulfate soundness test, the weighted loss shall not exceed ten (10)

mass percent.

The fine aggregate shall be free from damaging amounts of organic

impurities. If subjected to colorimetric test for organic impurities

and a color darker than the standard is produced, it shall be

rejected. However, when tested for the effect of organic impurities of

strength of mortar by AASHTO T71, the fine aggregate may be used

if the relative strength at seven (7) and twenty eight (28) days is not

less than ninety five (95) mass percent.

Fine aggregate shall be capable of developing eighty (80) percent of

the tensile strength of Ottawa sand. It shall be well graded from

course to fine and not contain more than one (1) percent clay, coal,

lignite and other deleterious substances such as shale, alkali, mica,coated grains, soft and flaky particles when tested according ASTM

methods. All fine aggregate shall conform to the following

requirements:

TABLE 2.10.3.2.1: PERCENT PASSING OF DIFFERENT

SIEVE SIZE

Sieve Size Percent Passing

9.5 mm (3

8 in ) 100

4.75 mm ( No. 4 ) 95 – 100

1.18 mm ( No. 16 ) 45 – 80

0.30 mm ( No. 50 ) 5 – 30

0.15 mm ( No. 100 ) 0 – 10


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2.10.3.2.2 COURSE AGGREGATES

Coarse Aggregate shall be composed of hard, strong crystalline rock

free form shale or other soft materials and free from any adherent

coating or vegetable matter. It can be crushed stones, gravel, blast

furnace slag, or other approved inert materials of similarcharacteristics, or combination thereof, having hard, strong, durable

pieces and free from any adherent coatings.

Coarse aggregates shall not contain more than one (1) mass percent

of material passing the 0.075 mm (No. 200) sieve, not more than

0.25 mass percent of clay lumps, nor more than 3.5 mass percent of

soft fragments.

If the course aggregate is subjected to five (5) cycles of the sodium

sulfate soundness test, the weighted loss shall not exceed 12 mass

percent.

It shall have a maximum mass percent of forty (40) when tested by

AASHTO T 96. If slag is used, its density shall not be less than one

thousand one hundred twenty (1120) kilograms per cubic meter or

seventy (70) pounds per cubic foot. Only one grading specification

shall be used and it shall conform to the following required grading

for coarse aggregate.

TABLE 2.10.3.2.2: GRADING FOR COARSE AGGREGATE

SIEVE DESIGNATION MASS PERCENT PASSING

STANDARD

mm

ALTERNATE

U.S. Standard

GRADING

A

GRADING

B

GRADING

C

75.0 3 in 100 - -

63.0 2 ½ in 90 – 100 100 100

50.0 2 in - 90 – 100 95 – 100

37.5 1 ½ in 25 – 60 35 – 75 -

25.0 1 in - 0 – 15 35 – 70

19.0 ¾ in 0 – 10 - -

12.5 ½ in 0 – 5 0 – 5 10 – 30

4.75 No. 4 - - 0 – 5

2.10.3.2.3 AGGREGATE TESTS

Testing of aggregates is a way by which the properties of a material

are routinely evaluated and compared with the appropriate

specification requirements. Samples of the aggregates to be usedshall be selected by the Engineer for tests at least thirty (30) days

before the start of actual concreting operations. It shall be the

responsibility of the Contractor to designate the sources of

aggregates to give the Engineer ample time to obtain the necessary

samples and submit them for testing.


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No aggregate shall be used until advice has been received that it has

satisfactory passed all tests to the satisfaction of the Engineer, at

which time written approval shall be given for its use.

In stating requirements for most materials, reference has been made

to AASHTO and ASTM Standard Specification for material. ThoseSpecifications, in turn, include reference to the respective AASHTO

and ASTM methods of sampling and testing. In such instances the

following methods of sampling and testing will govern:

TEST METHOD SPECIFICATION

Amount of Material Finer

than 0.075 mm Sieve in

Aggregate

AASHTO T 11

Unit Weight of Aggregate AASHTO T 19

Sieve Analysis of Fine and

Course Aggregates AASHTO T 27

Resistance to Abrasion of

Small Size Coarse

Aggregate by Use of the Los

Angeles Machine

AASHTO T 96

Soundness of Aggregate by

Use of Sodium Sulfate of

Magnesium Sulfate

AASHTO T 104

2.10.3.2.4 WATER

Water to be used in concrete works such as mixing, curing, or other

assigned application shall be sensibly clean and fresh. It shall be

free from oil, acids, alkali, sewage, and organic or other deleterious

matter. Water will be tested in accordance with and shall meet the

requirements of water from DPWH Standard and Specification for

Public Works and Highways. Drinking water may be used without

test. Where the source of water is shallow, the intake shall be so

enclosed as to exclude silt, mud, grass or other foreign materials.

2.10.3.2.5 METAL REINFORCEMENT

Reinforcement shall be detailed, fabricated, placed, and supported

in place in accordance with the following specifications:

Deformed and Plain Billet Steel (ASTM A 615)

Bars for Concrete Reinforcement AASHTO M 31

Deformed Bars – Steel and Plain ASTM A 616

ASTM A 617

For reinforcing bars to be welded, the following ASTM specifications

shall be accompanied by the requirements assuring satisfactory

weldability.


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Bar and Rod Mats for Concrete

Reinforcement

ASTM 187

(ASTM A 82)

Cold – Drawn Steel Wire for

Concrete Reinforcement

AASHTO M 32

(ASTM A 185)

Welded Steel Wire Fabric for

Concrete Reinforcement

(ASTM A 185)

AASHTO M 55

Except that the weld shear strength requirements of those

specification shall be extended to include a wire differential up to

and including six gauges.

Reinforcement shall be secured in place with concrete or metal

spacers. Metal spacers extending to the surface of the concrete or

wooden supports shall not be used. Reinforcement shall be free

from scale, rust, or coatings that will reduce the bond between

reinforcement and concrete.

2.10.3.2.6 RUBBER SEAL

Water stop shall be used in all vertical, horizontal, construction and

expansion joint as needed.

2.10.3.2.7 ADMIXTURES

When required by the engineer, admixtures shall be approved

quality. The Contractor shall furnish full details of the admixtures

prior to use in works. The employment of admixtures for concretemix shall be at the discretion of the Contractor and at no additional

cost to the Employer. The amounts and types of additives used shall

be as directed or approved by the Engineer and may be varied by

him according to the location of the work or for other reasons.

If air – entraining admixture is used, it shall conform to ASTM C

260.

If used, water – reducing, water proofing and water – reducing,

retarding and accelerating admixtures shall conform to the

requirements of ASTM C 494.

2.10.3.3 STORAGE OF MATERIALS

Immediately upon arrival at the site, cement and aggregates shall be

stored in storage designed for the purpose or in dry weather-tight and

properly ventilated structures with floors raised in a reasonable height

above ground level with adequate provision to prevent absorption of

moisture. Aggregates shall be stored on clean hard bases that permit free

drainage. Care must be taken so as to prevent foreign objects from mixing

and cross contamination between materials will be prevented. All storage

facilities shall be subject to approval by the Engineer and shall be such as

to permit each access for inspection and identification.

2.10.4 EXECUTION

2.10.4.1 CONCRETE QUALITY


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The quality and method and control of manufacture and transportation of

all concrete work irrespective of mix, whether reinforced or otherwise,

shall conform to the applicable portions of this specification. The

Engineer shall have the right to inspect the source(s) of materials, the

layout and operation of procurement and storage of materials, the

concrete batching and mixing equipment, the quality control system. Such

an inspection shall be arranged and Engineer’s approval obtained, prior to

starting of concrete works.

All plans submitted for approval of used for any structure in the project

shall clearly show the specified strength of concrete, F’c, of the specified

age for which it was designed.

Concrete that will be exposed to sulfate containing of other chemically

aggressive solutions shall be proportioned in accordance with

“Recommended Practice for Selecting Proportions for Concrete (ACI 613)”and “Recommended Practice for Selecting Proportions for Structural

Lightweight Concrete (ACI 613A)”.

2.10.4.2 METHODS OF DETERMINING THE PROPORTIONS OF CONCRETE

The determination of the proportions of cement, aggregates, and water to

attain the required strengths shall be made by one of the following

methods, but lower water – cement ratios may be required for

conformance with the quality of concrete.

a.Without Preliminary Test

Where preliminary test date the materials to be used in the concrete

have not been obtained the water to cement ratio for a given strength

of concrete shall not exceed the values shown on the following table.

When strengths in excess of two hundred eighty one (281) kilograms

per square centimeter or four thousand (4000) pounds per square inch

are required of when light weight aggregates of admixtures (other than

those exclusively for the purpose of entraining air) are used, the

required water to cement ratio shall be determined in accordance with

the next method to be mention.

TABLE 2.10.4.2:MAXIMUM PERMISSIBLE WATER TO CEMENT RATIO

FOR DIFFERENT CONCRETE’S COMRESSIVE

STRENGTH


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SPECIFIED

COMPRESSIVE

STRENGTH AT

28 DAYS, F’c

(PSI)

MAXIMUM PERMISSIBLE WATER – CEMENT

RATIO

Non air – entrained

concrete

Air – entrained

concrete

U.S. gallon

per 42.6

kilograms

bag of

cement

Absolute

ratio by

weight

U.S. gallon

per 42.6

kilograms

bag of

cement

Absolute

ratio by

weight

2500 7 ¼ 0.642 6 ¼ 0.554

3000 6 ½ 0.576 5 ¼ 0.465

3500 5 ¾ 0.510 4 ½ 0.399

4000 5 0.443 4 0.354

b.For combination of materials previously evaluated to be established by

trial mixtures.

Water to cement ratios for strength greater than that shown in the

above table maybe used provided that the relationship between

strength and water to cement ratio for the materials to be used has

been previously established by reliable test data and the resulting

concrete satisfies the requirements of concrete quality.

Where previous data are not available, concrete trial mixtures having

proportions and consistency suitable for the work shall be made using

at least three different water to cement ratios (or cement content in the

case of lightweight aggregates) which will produce a range of strengths

encompassing those required for the work. For each water to cement

ratio (or cement content) at least three specimens for each age to be

tested shall be made, cured and tested for strength in accordance with

ASTM C 39 and ASTM C 192.

The strength test shall be made at seventh(7th), fourteenth (14th) and

twenty eighth (28th) days at which the concrete is to receive load, as

indicated on the plans. A curve shall be established showing the

relationship between water to cement ratio (or cement content) and

compressive strength. The maximum permissible water to cement ratio

for the concrete to be used in the structure shall be that shown by the

curve to produce an average strength to satisfy the requirements of the

strength test of concrete provided that the water to cement ratio shall

be no greater than that required by concrete quality when concrete that

is to be subjected to the freezing temperatures shall have a water –cement ratio not exceeding six (6) gallons per bag and it shall contain

entrained air.

Where different materials are to be used for different portions of the

work, each combination shall be evaluated separately.


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2.10.4.3 CONCRETE PROPORTIONS AND CONSISTENCY

The Contractor shall design concrete proportion to produce concrete

required strength. Notwithstanding the acceptance by the Engineer of any

mix design and series of trial mixes, variations may be made to the

proportions when considered necessary by the Engineer.

The proportion of aggregate to cement for any concrete shall be such as to

produce a mixture which will work readily into the corners and angles of

the form and around reinforcement with the method of placing employed

on the work, but without permitting the materials to segregate or excess

free water to collect on the surface. The methods of measuring concrete

materials shall be such that the proportion can be accurately checked at

any time during the work.

2.10.4.4 SAMPLING AND TESTING OF STRUCTURAL CONCRETE

The Contractor shall provide the equipment necessary to determine the

compacting factor of freshly mixed concrete at each place where concrete

is being made and shall determine the compacting factor of the freshly

mixed concrete. At least one (1) set of sample consisting of three (3)

concrete cylinder test specimens, one hundred fifty (150) by three

hundred (300) millimeter shall be taken from each class of concrete placed

each day, and each serves to represent not more than seventy five (75)

cubic meter of concrete.

2.10.4.5 CONSISTENCY

Concrete shall have a consistency such that it will be workable in the

required position. It shall be such that it will flow around reinforcing steel

but individual particles of the coarse aggregate when isolated shall show a

coating or mortar containing its proportionate amount of sand. The

consistency of concrete shall be gauged by the ability of the equipment to

properly place it and not by the difficulty of mixing water shall be

determined by the Engineer and shall not be varied without his consent.

Concrete as dry as it is practical to place with equipment specified shall

be used.

2.10.4.6 STRENGTH TEST OF CONCRETE

Concrete shall be subjected to compressive and flexural strength test as

specified in ASTM C 31, “Making and Curing Concrete Compressive and

Flexural Strength Tests Specimens in the Field”. Each class of concrete

shall be represented by at least five (5) tests having an accumulation of

ten (10) specimens. Two (2) specimens shall be made for each test at a

given age, and not less than one (1) test shall be made for each one

hundred fifteen (115) cubic meter of structural concrete, but there shall

be at least one (1) test for each day concreting. The Engineer may requirea reasonable number of additional tests during the progress of the work.

Samples from which compression test specimens are molded shall be

secured in accordance with ASTM C 172. Specimens made to check the

adequacy of the proportions for strength of concrete or as a basis for

acceptance of concrete shall be made and laboratory – cured in

accordance with ASTM C 31. Additional test specimens cured entirely


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under field conditions may be required by the Engineer to check the

adequacy of curing and protection of the concrete.

If it appears that the laboratory cured specimen will fail to conform to the

requirements for strength, the Engineer shall have the right to order

changes in the concrete mix sufficient to increase the strength to meetthese requirements. The strengths of any specimen cured on the job are

intended to indicate the adequacy of protection and curing of the concrete

and may be used to determine as to when the forms may be stripped,

shoring removed or the structure placed in service. In the opinion of the

Engineer, the strength of the job cured specimen are excessively below

those of the laboratory cured specimen, then the Contractor may be

required to improve the procedures for protecting and curing concrete.

The age for strength tests shall be twenty eight (28) days or, where

specified, the earlier age at which the concrete is to receive its full load ofmaximum stress. Additional test may be made at earlier ages to obtain

advance information on the adequacy of strength development where age

– strength relationships have been established for the materials and

proportions used.

To conform to the requirements of this item:

a.For structures designed in accordance with working stress design

method of this chapter, the average of any five consecutive strength

tests of the laboratory – cured specimens representing each class of

concrete shall be equal to or greater than the specified strength, F’c and

not more than twenty (20) percent of the strength test shall have values

less than that specified.

b.For structures designed in accordance with the ultimate strength

design method of this chapter, and for pre – stressed structures the

average of any three consecutive strength test of the laboratory cured

specified representing each class of concrete shall be equal to or greater

than the specified strength, F’c and not more than ten (10) percent of

the strength tests shall have values less than the specified strength.

The Contractor shall provide for all costs in the making of such tests

including allowing free access to the work for the selection of samples,

providing moist storage facilities for specimen, affording protection of the

specimen against injury or loss through his operations, and furnishing

material and labor required for the purpose of taking and testing of

samples. The Contractor shall make slump tests in the field and when

instructed by the Engineer in the presence of the Engineer's

representatives.

The Engineer may request that dynamic testing or loading test to be

executed when the results of the laboratory test are not satisfactory for

completed works. The Contractor at his own cost shall carry out testing

and inspection work.

2.10.4.7 BATCHING


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When batches are hauled to the mixer, bulk cement shall be transported

either in waterproof compartments or between the fine and course

aggregates. When cement is placed in contact with moist aggregates,

batches will be rejected unless mixed within one half (½) hours of such

contact. Sacked cement may be transported on top of the aggregates.

Batches shall be delivered to the mixer separate and intact. Each batch

shall be dumped cleanly into the mixer without loss, and, when more

than one batch is carried on the truck, without spilling of material from

one batch into another.

2.10.4.8 MIXING AND DELIVERY

Mixing of concrete shall continue until there is a uniform distribution of

material and the concrete is uniform in color and consistency. Concrete

may be mixed at the site of construction, at a central point and truck

mixing or by a combination of central point mixing and truck agitating.

Mixing the delivery of concrete shall be in accordance with the

appropriate requirements of AASHTO M 157 except as modified in the

following paragraphs of this section, for truck mixing or a combination of

central point and truck mixing or truck agitating.

The mixer shall be operated at the drum speed as shown on the

manufacturer’s name plate on the mixer. Any concrete mixed less than

the specified time shall be discarded and disposed of by the Contractor at

his own expenses.

The timing device on the stationary mixers shall be equipped with a bell

or any suitable warning device adjusted to give a clearly audible signal

each time the lock is released.

Mixes and weighs batches shall be maintained in first class condition

throughout the time period and any mixer or plant which is faulty shall

not be used. A mixer of any type shall be maintained in a clean

serviceable condition and their accuracy periodically checked.

If volumetric measurement is allowed, the weight proportions shall be

converted to equivalent volumetric proportions. In such cases, suitableallowance shall be made for variations in the moisture condition of the

aggregate.

2.10.4.9 CONCRETE SURFACE FINISHES

2.10.4.9.1 CURING CONCRETE

All freshly deposited concrete shall be protected from premature

drying and excessively hot or cold temperatures, and mechanical

injury and shall be maintained with minimal moisture loss at a

relatively constant temperature for the period of time necessary forthe hydration of the cement and proper hardening of the concrete.

Curing of concrete in the field shall conform to the required standard

of ASTM C31/C31 M, “Standard Practice for Making and Curing

Concrete Test Specimens in the Field”.


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The Contractor shall protect all concrete work against injury from

outside elements and defacement of any nature during construction

operations. All concrete, particularly exposed surfaces shall be treated

immediately after concreting or cement finishing is completed, and

shall be provided with continuous moist curing for at least seven (7)

days regardless of the ambient air temperature. Walls and vertical

surfaces may be covered with continuously saturated burlap or by

other approved means. Horizontal surfaces, slabs, and other items

shall be inundated with pool of water to a depth of one and 2 tenths

(1.2) centimeter and kept continuously wet with the use of sprinklers.

Finished surfaces and slabs shall be protected from the direct rays of

the sunlight to prevent shrinking and cracking.

The curing method shall be one or more of the following:

a. Water Method – The concrete shall be kept continuously wet by theapplication of water for a minimum period of seven (7) days after

the concrete has been placed.

b.Curing Compound – Surfaces exposed to the air may be cured by

the application of an impervious membrane approved by the

Engineer.

c.Waterproof Membrane Method – The exposed finished surfaces of

concrete shall be sprayed with water, using a nozzle that so

atomizes the flow that a mist and not a spray are formed until the

concrete has set, after which a curing membrane of waterproof

paper or plastic sheeting shall be placed.

d.Forms-in-Place Method – Formed surfaces of concrete may be cured

by retaining the form in place. The forms shall remain in place for a

minimum period of seven (7) days after the concrete has been

placed, except that for members over fifty (50) centimeters in least

dimension, the forms shall remain in place for a minimum period

of five (5) days.

e.Curing Cast-in-Site Concrete – All newly placed concrete cast-in

into the structures shall be cured by the water method, the forms-

in-place method, or as permitted herein, by the curing compound

method.

f.Curing Pre-Cast Concrete Piles – All newly placed concrete for pre-

cast concrete piles, conventionally reinforced or pre-stressed shall

be cured by the “Water Method” as described in subsection “Curing

Concrete”, except that the concrete shall be kept under moisture for

at least fourteen (14) days. All the option of the Contractor, steam

curing maybe used in which case the steam curing provisions of

DPWH SS subsection 407.3.8 (6) curing pre-cast concrete shall

apply except that the concrete shall be kept wet for at least seven

(7) days including the holding and steaming period.

2.10.4.9 ACCEPTANCE OF CONCRETE

2.10.4.9.1 STRENGTH OF CONCRETE


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Concrete not meeting the requirements of this specification shall be

considered potentially deficient and may be rejected. The strength of

concrete shall be deemed acceptable if the average of three (3)

consecutive strength test results is equal to or exceeds the specified

s

Documents

Weir Specification (Especificaciones técnicas de construcción de vertedeteros)