Different types of Cement

Special types of cement-

1-Rapid hardening cement-

This is a type of cement which develops higher rate of gain of strength& [must not be confuse with quick setting cement which only sets quickly].cement attain the strength at the age of 3 days equivalent to that attain by OPC in 7 days.

This higher strength in initial stage is attributed to the higher fineness of the cement & increase the proportion of C₃S (Specific surface area should not be less than 3250 Cm²/gm.). & C₃S is approximately 56%.

Application of this cement-

1- Cold weather concreting

2- Emergency repair work.

3- Pavement construction.

4- Where formwork is to be reutilize for speedy construction.

2-Extra Rapid hardening cement-

Different Types of Cement

The cement is formed by intergrinding rapid hardening cement clinker with calcium chloride. Under normal conditions proportion of CaCl₂ must not be greater than 2%.(But it increases corrosion in reinforcement so it is not used now days.)

The cement must be mixed, transported, place, compacted, & finished within 20 minute of the addition of water in it. The strength of the cement is approximately 25% more than rapid hardening cement at the age of 1 or 2 days, 10 to 15% more at the age of 7 days.

This rate of gain of strength in this cement reduced with age & at the age of 90 days strength of all OPC, Rapid hardening cement& extra rapid hardening cement is approximately same.

3-Sulphate resisting cement-

Sea water contain sulphur in excess & it leads to volume change. Sulphur is also found in soil, in sewage also sulphur is available. OPC is highly susceptible to the attack of sulphates specially (MgSO₄) which reacts with both, Calcium hydroxides to form calcium sulphate& calcium aluminate to form calcium sulpho Aluminate.

Volume of which is approximately 227% more than the original volume, that leads to the development of the cracks in the structure in which it is used for construction. In order to avoid this, proportion of lime& alumina is reduced in the cement such that C₃A is not greater than 5% & (2C₃A+ C₄AF) is not greater than 25%.

The cement finds its application in-

1- Marine construction

2- Sewage treatment works.

3- Foundation works.

4- In the construction of pipes that are to be laid in the marshy areas.

4-Super sulphate cement-

The cement is prepared by intergrinding 80 to 85% granulated blast furnace slag 10 to 15% hard burnt gypsum & 5% cement clinkers. The cement offers very high resistance against the attack of chlorides& sulphates.

Note- Residue left after the extraction of metal is known as slag. Strength is less, resisting property is more, and cost is less. Applications are same as sulphate resisting cement.

5-Portland slag cement-

The cement is prepared by intergrinding granulated blast furnace slag, hard burnt gypsum& cement clinkers in definite proportion. Generate low heat of hydration so suitable for mass concreting.

The cement offers-

1- Low heat of hydration.

2- Higher resistance against the attack of chlorides & sulphates.

3- Higher water tightness.

4- Lower the permeability due to lesser size of particles.

6- Quick setting cement-

The cement is obtained by adding small % of alumina in finely grinded cement clinkers & reducing the proportion of calcium sulphate [CaSO₄]. Its initial setting time is 5 minute and final setting time is 30 minute.

Its application in-

1- Grouting operation.

2- under water concreting.

7- Low heat cement-

The cement is prepared by reducing the proportion of C₃A &C₃S & increasing the proportion of C₂S to compensate the loss of strength [C₃A is approximately 5%, C₃S is approximately 46%, C₂S is approximately 34%.]

This cement is also develops slower rate of gain of strength. Heat of hydration of the cement at the age of 7 days is not greater than 65 cal/gm & at the age of 28 days is not greater than 75 cal/gm.

Application of this cement- Example- Bridges, Hydraulic structure & Dams etc.

8-Portland pozzolana cement-

This cement is prepared by intergrinding cement clinkers with 10 to 15% pozzolanic material. Pozzolanic material are those which itself do not possess any cementous property , but when finally grinded in the presence of water , it reacts with calcium hydroxide released during the hydration of the cement& leads to the formation of cementous compound.

Property of this cement-

1- Attains compressive strength with age.

2- Offers higher water tightness.

3- Offers higher resistance against the attacks of chlorides and sulphates.

4- Offers higher resistance against expansion.

5- Offers higher plasticity.

6- Offers low heat of hydration.

The cement finds its application-

1- Marine water for construction.

2- Construction of pipes in marshy area.

9- Hydrophobic cement-

The cement is prepared by intergrinding cement clinkers with water repellant film forming substances like stearic acid & Oleic acid.

This water repellant film which is formed around the cement particles reduces the rate of deterioration of the cement due to long storage & transportation period.

10- High alumina cement-

The cement is obtained by intergrinding the clinkers obtain by the calcination of bauxite & lime stone. [Bauxite is a ore of alumina & lime stone is a ore of lime] Proportion of alumina in this cement must not be less than 32% & ratio of % of alumina to that of lime is in the range of 0.85 to 1.3.

The cement offers higher initial setting time [3.5 hour] & lower final setting time [5 hour] .Hence more time is available to work with the cement. The cement can also resist high temperature.

It can resist action of acids up to greater extent. It also offers higher rate of gain of strength as it attains 20% of its ultimate strength within a day & substantial portion of the ultimate strength in 6 to 8 hours.

👉Part-1- Constituents Present in OPC

👉Part-2- Bogues Compound in Cement and Uses

👉Part-3- Testing of Cement Consistency Test

👉Part-4- Initial and Final Setting time Test of Cement

👉Part-5- Compressive and Tensile Strength Test of Cement

👉Part-6- Different Types of Cement and their Uses

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