OPC (Ordinary Portland Cement) is used for almost all purposes. It has adhesive and cohesive properties in order to form a better bond with other materials. It solidifies when mixed with water. It is a good binding medium and is most important component of concrete.

Manufacture

Cement is obtained by burning a mixture of the following materials.

  •   Siliceous materials
  •  Argillaceous materials
  •  Calcareous materials

Or materials containing silica alumina and lime

The temperature of burning is 1400C. The clinker so obtained is cooled and powdered to fineness. Different properties are given to the cement by mixing the above materials in different proportions with small percentages of other chemicals.

Cement is a complicated chemical compounds of

  • Tricalcium silicate
  • Dicalcium silicate
  • Tricalcium aluminate
  • Tetracalcium alumino ferrite

Tricalcium silicate has the property of hydrating rapidly. It gives early and ultimate strength.

Rapid hardening cement (IS8041)

It is made like OPC but it differs in respect of chemical composition, degree of burning and grinding.

It must have better fineness than OPC. For the same water cement ratio it attains strength in 3 days what OPC gains in 7 days. Its used in road work.

Portland-Pozzolana cement (PPC)(IS1489)

It is made by blending Portland cement and fine pozzolana. It can also be made by intergrinding Portland cement clinker and pozzolana. Pozzolana content varies from 10% to 25%, by weight of cement. Pozzolana provides a stable lime. Free lime causes chemical attack. It can be used where sea water present. Its used in the construction of dams, because of lower heat evolution. Pozzolana is obtained from burnt clay of fly ash.

White cement

For getting white color iron oxide  content is reduced. Raw materials of this cement are lime stone and china clay.