Types of Cement:
Following are the different types of cement used in construction works.
1. Rapid Hardening Cement:
Rapid hardening cement is very similar to ordinary portland cement (OPC). It contains higher c3s content and finer grinding. Therefore it gives greater strength development at an early stage than OPC. The strength of this cement at the age of 3 days is almost same as the 7 days strength of OPC with the same water-cement ratio.
The main advantage of using rapid hardening cement is that the formwork can be removed earlier and reused in other areas which save the cost of formwork. This cement can be used in prefabricated concrete construction, road works, etc.
2. Low Heat Cement:
Low heat cement is manufactured by increasing the proportion of C2S and by decreasing the C3S and C3A content. This cement is less reactive and its initial setting time is greater than OPC. This cement is mostly used in mass concrete construction.
3. Sulfate Resisting Cement:
Sulfate resisting cement is made by reducing C3A and C4AF content. Cement with such composition has excellent resistance to sulfate attack. This type of cement is used in the construction of foundation in soil where subsoil contains very high proportions of sulfate .
4. White Cement:
White cement is a type of ordinary Portland Cement which is pure white in color and has practically the same composition and same strength as OPC. To obtain the white color the iron oxide content is considerably reduced. The raw materials used in this cement are limestone and china clay.
This cement, due to its white color, is mainly used for interior and exterior decorative work like external renderings of buildings, facing slabs, floorings, ornamental concrete products, paths of gardens, swimming pools etc.
5. Portland Pozzolana Cement:
Portland pozzolana cement is produced either by grinding together, portland cement clinkers and pozzolana with the addition of gypsum or calcium sulfate or by intimately and uniformly blending portland cement and fine pozzolana.
It produces lower heat of hydration and has greater resistance to attack of chemical agencies than OPC. Concrete made with PPC is thus considered particularly suitable for construction in sea water, hydraulic works and for mass concrete works.
6. Hydrophobic Cement:
Hydrophobic cement is manufactured by adding water repellant chemicals to ordinary portland cement in the process of grinding. Hence the cement stored does not spoiled even during monsoon. This cement is claimed to remain unaffected when transported during rains also. Hydrophobic cement is mainly used for the construction of water structures such dams, water tanks, spillways, water retaining structures etc.
7. Colored Cement:
This Cement is produced by adding 5- 10% mineral pigments with portland cement during the time of grinding. Due to the various color combinations, this cement is mainly used for interior and exterior decorative works.
8. Waterproof Portland Cement:
Waterproof cement is prepared by mixing with ordinary or rapid hardening cement, a small percentage of some metal stearates (Ca, Al, etc) at the time of grinding. This cement is used for the construction of water-retaining structure like tanks, reservoirs, retaining walls, swimming pools, dams, bridges, piers etc.
9. Portland Blast Furnace Cement:
In this case, the normal cement clinkers are mixed with up to 65% of the blast furnace slag for the final grinding. This type of cement can be used with advantage in mass concrete work such as dams, foundations, and abutments of bridges, retaining walls , construction in sea water.
10. Air Entraining Cement:
It is produced by air entraining agents such as resins, glues, sodium salts of sulfate with ordinary portland cement.
11. High Alumina Cement:
High alumina cement (HAC) is a special cement, manufactured by mixing of bauxite ( aluminum ore) and lime at a certain temperature. This cement is also known as calcium aluminum cement (CAC). The compressive strength of this cement is very high and more workable than ordinary portland cement.
12. Expansive Cement:
The cement which does not shrink during and after the time of hardening but expands slightly with time is called expansive cement. This type of cement is mainly used for grouting anchor bolts and prestressed concrete ducts.
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