Sand

Construction Materials

• Sand

• Lime

• Cement

Sand

• Definition: Naturally occurring granular

material composed of finely divided rock

and mineral particles

• Constituents: Varies on location and

availability of local rock sources

Silica, calcium carbonate

Sources

• Pit sand : free from salt, good for mortar, no stains, sharp

angular grains

• River sand: banks or beds of river, finely rounded grains,

almost white, clean

• Sea sand: sea shores, finely rounded grain, light brown in

colour, contains salt : causes moisture absorption from

atmosphere , filling of basements, not useful for mortar and

other work

Classification

• Fine sand: pass through

screen 1.5875mm, for

plastering

• Coarse sand: 3.175mm

screen, masonry work

• Gravelly sand: 7.62mm,

concrete work

Bulking of sand

• Presence of moisture

increase in volume of

sand

• with 5-8%, increase of

volume is 20-40%

• Finer the material , more

is the volume increase

Properties

• Chemically inert

• Clean, coarse, free from organic or vegetable

matter, 3-4% of clay is permitted

• Should contain sharp angular coarse and durable

grain

• No salts

• Well graded, to suit various sizes and proportion

Function

• Bulk: acts as adulterant, volume of mortar is increased,

reduction in cost, doesn’t increase strength of mortar

• Shrinkage: prevents excess shrinkage of mortar,

cracking of mortar during setting is prevented

• Strength: resistance of mortar against crushing

• Surface area: more surface area is offered for

spreading

• Setting: if fat lime is used in mortar, setting time is

increased

Tests

• Adding of water: layer of clay settle down

• Taste: no salts should be present

• Rubbing against fingers should leave no

stains

• Colour and sharpness of sand

• Other mechanical analysis

Substitutes

• Stone screenings:

Sharp, more strenght

for huge quantity, big

construction projects,

• Burnt clay or surkhi:

finely grinding burnt clay

Lime

• Definition: Due to calcination of limestone, the

moisture and carbon dioxide are removed from it.

The product which remains thereafter is known as

lime

• Limestone is a sedimentary rock

• It is mainly made up of calcium carbonate

• It is actually a mixture of substances

Terminology

• Calcination: heating to redness in contact with air

• Hydraulicity: property of lime to set or harden in

damp places, water or thick masonry walls where

there is no free circulation of air

• Setting: Process of hardening of lime after it has

been converted into paste form (different from

drying where water evaporates)

Quick lime

• obtained by calcination of comparatively pure

limestone, great affinity for moisture, amorphous, not

crystalline and highly caustic having no affinity for

carbon acid

Slaked (hydrated) lime

• Product obtained by slaking of quick lime, (hydrate of lime)

• White powder form

• The thin pourable suspension of slaked lime in water is known as milk

of lime.

• Should be kept in damp place

• Should be used fresh,

• Slaking of lime:

sufficient quantity of water added to quick lime

due to chemical reaction , quick lime cracks,

swells and falls into powder form,

Classification

• Fat lime

• Hydraulic lime

• Poor lime

Fat lime

• Fat lime: high calcium lime , rich lime,

pure lime or white lime

• Slakes vigorously, volume is increased to

about 2 to 2 ½ times the volume of quick

lime.

• Hardens very slowly, high degree of

plasticity, soluble in water which is

frequently changed

• Perfectly white colour, sets slowly in

presence of air

• Impurities is less than 5%

• Used in whitewashing and plastering, for

lime mortar in brick and stone masonry

• Whith surkhi, lime mortar posses good

setting and hydraulic properties, used for

foundations, thick masonry walls etc

Hydraulic lime (water lime)

• It sets under water

• Contains some amount of ferrous oxide

• Increase in %age of clay making slaking

difficult and increases hydraulic property

• Presence of 30% of clay resembles

hydraulic lime to natural cement

• Used for thick walls where there is no free

air circulation, plaster work

• Colour is not perfectly white

• Forms thin paste with water

• Does not dissolve in water though it is

frequently changed

Poor lime

• Impure lime or lean lime,

• Contains more than 30% of clay

• Slakes slowly

• Sets very slowly

• Poor binding properties , so poor mortar

• Muddy white colour

• It forms thin paste with water

• Does not dissolve in water though it is

frequently changed

Comparision

Item Fat lime Hydraulic lime

composition Obtained from pure carbonate of lime, only

5% of impurities

Obtained from limestone

containing clay of about 5 to

30% + some amount of ferrous

oxide

Slaking action Slakes vigorously, volume is increased to

about 2 to 2 ½ times the volume of quick

lime.

Accompanied by Sound and heat

slaking slowly, volume is

slightly increased, No sound

and heat

Setting action Hardens very slowly in presence of air

Sets fast under water

hydraulicity Does not possess hydraulic property Posses hydraulic property

colour Perfectly white colour, sets slowly in

presence of air

Not so white

strength Not very strong Very strong

CEMENT

• Natural cement: Obtained by burning

and crushing the stones containing clay,

carbonate of lime and some amount of

carbonate of magnesia

• Colour: brown, best variety known as

roman cement

• Not as strong as artificial cement , limited

use in practice

Properties

• Gives strenght to

masonry

• Excellent binding material

• Easily workable

• Good resistence to the

moisture

• Possesses good plasticity

• Stiffens and hardens early

Setting action of

cement

• Setting action: when water is added,

chain of chemical reactions between

ingredients and water results in a

chemical compounds, its long ,

• Sticky paste gradually thickening till it

achieves a rock like state

• Ordinary cement achievies 70% of its

final strenght in 28dsy, and 90% in a

year

Functions

• Lime: excess lime makes unsound, causes to expand and disintegrate .

Less of lime decreases the strength and causes cement to set quickly

• Silica: imparts strength ,Excess silica increases strength but prolongs

setting time

• Alumina: imparts quick setting property to cement: acts as flux and

lowers the clinkering temperature. excess alumina weakens the cement

• Calcium sulphate in the form of gypsum, increases initial setting time

• Iron Oxide: imparts colour, hardness and strength

• Magnesia: in small quantity imparts hardness and colour. High content

makes cement unsound

• Sulphur: small amount is used to make cement become sound. In

excess makes it unsound

• Alkalies: in excess causes alkali aggregate reaction, effloesecnce and

stating when used in mortar or concrete

Artificial cement

• The best variety of artificial cement is known

as portland cement or ordinary cement or

normal setting cement, finely ground material

consiting of lime, silica,iron alumina.

• When mixed with with water, it forms a paste

which hardens and binds the aggregate

togsther to form concrete

Rapid hardening

cement

• Attains high strength in early bcoz of increased lime

content in composition, burning at a higher temperature

and finger grinding.

• This type of cement is used in concrete when early high

strength area needed either to remove formwork quickly

or to carry out construction speedily or in cold weather

construction to reduce the period of protection against

temperature or to achieve economy for higher early

strengths

Quick setting

cement

• Starts setting within 5 min of water addition and becomes hard

like stone within 30 min or so.

• Produced by adding small percentage of aluminum sulphate as

an accelerator and also by reducing percentage of gypsum or

retarded along with finer grinding

• This type of cement is used where concrete work is to be

completed in very short period such as concreting in static o

running water

White cement

• Variety of ordinary cement and is prepared from

such raw materials which are practically free from

iron oxide it is more costly and s used widely only

for architectural purposes such as pre-cast curtain

wall and facing panels, terrazo surface, etc

Colour

• Cements of desired colour are produced by

intimately mineral pigments with ordinary cement,

coloured cement are widely used for decorative

works in floors, external surfaces, walls, etc

Pozzolona cement

• It is volcanic powder which when mixed with

portland cement clinkers forms pozzolanic

cement. This cement is largely used in marine

structures, sewege works, and for laying concrete

under water such as bridge piers, dams, etc

Field test for cement

• Colour : uniform, typical

grey with a light greenish

shade

• Physical properties:

smooth when touched or

rubbed in between two

fingers if rough indicates

adultration with sand,

• If ahnd is inserted

THE CEMENT MANUFACTURING PROCESS quarry

raw grinding and burning

grinding, storage, packing, dispatch

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THE CEMENT MANUFACTURING PROCESS

1. BLASTING : The raw materials that are used to manufacture cement (mainly limestone and clay) are blasted

from the quarry.

Quarry face

1. BLASTING 2. TRANSPORT

3. CRUSHING AND TRANSPORTATION : The raw materials, after crushing, are

transported to the plant by conveyor. The plant stores the materials before they are

homogenized.

quarry

3. CRUSHING & TRANSPORTATION

2. TRANSPORT : The raw materials are loaded into a dumper.

crushing

conveyor

dumper

storage at

the plant

loader


1. RAW GRINDING : The raw materials are very finely ground in order to produce the raw mix.

1. RAW GRINDING

Raw grinding and burning

2. BURNING

2. BURNING : The raw mix is preheated before it goes into the kiln, which is heated by a flame that can

be as hot as 2000 °C. The raw mix burns at 1500 °C producing clinker which, when it leaves the kiln, is

rapidly cooled with air fans. So, the raw mix is burnt to produce clinker : the basic material needed to

make cement.

conveyor Raw mix

kiln

cooling

preheating

clinker

storage at

the plant

Raw mill


1.GRINDING : The clinker and the gypsum are very finely ground giving a “pure cement”. Other secondary

additives and cementitious materials can also be added to make a blended cement.

1. GRINDING

Grinding, storage, packing, dispatch

2. STORAGE, PACKING, DISPATCH

2. STORAGE, PACKING, DISPATCH :The cement is stored in silos before being dispatched either in

bulk or in bags to its final destination.

clinker

storage

Gypsum and the secondary additives are added

to the clinker.

silos

dispatch

bags

Finish grinding

MORTAR

• Mortar is a workable paste used to bind construction blocks together and

fill the gaps between them

• Paste prepared by adding required qty of water to a mixture of binding

material like cement or lime and fine aggregate like sand

1: Matrix:

binds the particles of

adulterant

durability, quality and

strength

Cement , lime

Mortar

2: Adulterant:

Particles that gives volume to

mortar

Sand, surkhi etc

classification • Bulk density: Heavy mortar

Light mortar

• Kind of binding material

lime mortar

surkhi mortar

cement mortar

gauged mortar

gypsum mortar

• Nature of application

Brick laying mortar

finishing mortar

• Special mortars

Fire resistant

Lightweight

Packing

Sound absorbing

X ray shielding

Bulk density:

• Heavy mortar :

density of 15kN/m3 or more prepared form

heavy quartz or other sand

• Light mortar:

density is less than 15kN/m3 , prepared form

light porous sands from pumice or fine

aggregate

Kind of binding material

• lime mortar : fat lime shrinks to great extent and require 2-3 times its

volume of sand, water logged areas and damp situations

hydraulic lime consumed within 1 hr after mixing, more strength ,used in

damp situations

high plasticity, easily placed, good cohesiveness, with other surface and

shrinks very little, durable, hardens slowly,

• surkhi mortar : used instead of sand, not chemically inert, cannot used

with cement ad matrix, for ordinary work in foundation and superstructure,

not for plastering

• cement mortar: 1:2 to 1:6 or more , proportion depends on durability, and

working conditions, high strength, water resisting properties for

underground construction,

• gauged mortar : to lime mortar cement is added to achieve early strength,

lime mortar is economical, bedding, thick brick walls

• gypsum mortar : gypsum binding materials

Nature of application

• Brick laying mortar :

for brick walls, depending on working conditions,

kind of binding material

• finishing mortar :

common plastering- cement or lime mortar

Architectural and ornamental effects

Consideration of mobility, water retention, resistance

to atmospheric actions etc

Special mortars

• Fire resistant :used with fire-bricks for lining

furnaces, fire places, ovens etc

• Lightweight : saw dust, wood powder etc is added

to lime or cement mortar,

• Packing : to pack oil wells, water resistance, to

form water proof plugs in cracks and voids. San

cement, sand loam, and sand cement loam

• Sound absorbing: to reduce noise level, sound

absorbing a material like jute fibres, coir, light

weight porous material

• X ray shielding: plastering coat to walls and

ceiling, heavy mortar -22kN/m3 bulk density

Documents

Sand