CEMENTCEMENT

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BY K.R.SHANKAR M.E.,

ASSISTANT PROFESSOR DEPARTMENT OF CIVIL ENGINEERING

EBET GROUP OF INSTITUTIONS TRIPPUR DISTRICT

TAMUL NADU, INDIA – 638108 Email ID – krs.civil@ebet.edu.in

WHAT IS CEMENT???? Material with adhesive and cohesive properties

Any material that binds or unites - essentially like glue

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FUNCTION OF CEMENT

To bind the sand and coarse aggregate

together to fill voids in between sand and coarse

aggregate particle to form a compact mass

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Oxide Common Name Approx. Amount (%)

CaO Lime 60-67

SiO2 Silica 17-25

Al2O3 Alumina 3-8

Fe2O3 Iron-oxide 0.5-6

MgO Magnesia 0.1-4

Na2O Soda0.2-1.3

K2O Potassium

SO3 Sulfuric Anhydride 1-3

CONSTITUENTS OF CEMENT

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FUNCTIONS OF INGREDIENTS

Lime

Lime is the important ingredient of cement and its proportion is to be

maintained carefully.

Lime in excess makes the cement unsound and causes the cement to expand

and disintegrate.

On the other hand, if lime is in deficiency the strength of the cement is

decreased and it causes cement to set quickly

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Silica: This also an important ingredient of cement and it

gives or imparts quick setting property to imparts strength to

cement.

Alumina: This ingredient imparts quick setting properly to

cement. Excess alumina weakens the cement.

Calcium Sulphate: This ingredient is in the form of gypsum

and its function is to increase the initial setting time of

cement.

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Magnesia: The small amount of this ingredient imparts hardness and

colour to cement. Excess Magnesia affects soundness of the cement.

Sulphur: A very small amount of sulphur is useful in making sound

cement. If it is in excess, it causes the cement to become unsound.

Alkalies: Most of the alkalies present in raw material are carried away

by the flue gases during heating and only small quantity will be left. If

they are in excess in cement, efflorescence is caused.

Iron Oxides: Provides color, hardness and strength. It also assits in

fusion of raw materials in manufacturing of cement.

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Best binding material

High plastic properties

High strength

Hardens in short time

High resistance to water and other atmospheric effects

PROPERTIES OF CEMENT

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QUALITY REQUIREMENTS OF CEMENT

Homogeneous and uniform in colour

Free from lumps and should sink in water in small

quantity is placed on surface of water

Ratio of percentage of alumina to that of iron oxide

should not be less than 0.66

Weight of magnesia not exceeds 5%

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Total sulphur content not exceeds 2.75%

Specific surface should minimum 2250 mm2/gm

Expansion of cement should not exceeds 10 mm

Initial setting time should not be less than 30 mints.

Final setting time should be around 10 hours

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GRADE OF CEMENT:

The commonly used Portland Cement in India are as follows

1. 33 Grade (IS 269:1989)

2. 43 Grade (IS 8112:1989)

3. 53 Grade (IS 12269:1987)

The Grade is nothing but its 28 days mean compressive

strength of mortar cube. For

1. 33 Grade it must be exceeding 33 N/mm2

2. 43 Grade it must be exceeding 43 N/mm2

3. 53 Grade it must be exceeding 53 N/mm2

TYPES OF CEMENT Rapid Hardening Cement

Quick setting cement

Low Heat Cement

Sulphates resisting cement

Blast Furnace Slag Cement

High Alumina Cement

White Cement

Coloured cement

Pozzolanic Cement

Air Entraining Cement

Hydrographic cement

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Types of Cement Purpose

Rapid Hardening

Cement

Attains high strength in early days it is used in concrete where form work are removed at an early stage.

Quick setting cement

Used in works is to be completed in very short period and concreting in static and running water

Low Heat Cement

It is used in massive concrete construction like gravity dams

Sulphates resisting Cement

It is used in construction exposed to severe sulphate action by water and soil in places like canals linings, culverts,

retaining walls, siphons etc.,

Blast Furnace Slag Cement

It can used for works economic considerations is predominant.

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High Alumina Cement

It is used in works where concrete is subjected to high temperatures, frost, and acidic action.

White CementIt is more costly and is used for architectural purposes

such as pre-cast curtain wall and facing panels, terrazzo surface etc.,

Coloured cement They are widely used for decorative works in floors

Pozzolanic Cement

It is used in marine structures, sewage works, sewage works and for laying concrete under water such as

bridges, piers, dams etc.,

Air Entraining Cement

This type of cement is specially suited to improve the workability with smaller water cement ratio and to

improve frost resistance of concrete.

Hydrographic cement This cement has high workability and strength

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Masonry Cement They are widely used for masonry work

Oil-well Cement

It is used in high pressure and temperature in sealing water and gas pockets and setting cause during the

drilling and repair of oil well

Expanding Cement

This type of cement is used in repairing concrete surface

Acid Resisting Cement

It is used in chemical industry