Wednesday, 15 June 2016

What is CEMENT & its Chemical properties

Cement is a commonly used binding material in the construction. The cement is obtained by burning a mixture of calcarious and argillaceous material at a very high temperature and then grinding the clinker so produced to a fine powder.

It was first produced by a mason Joseph  Aspdin in England in 1924. He named it as portland cement.

#Chemical properties of ordinary portland cement.

(a) Tricalcium silicate (3 CaO.SiO2) is present 40%

(b) Dicalcium silicate (2CaO.SiO2) is present 30%

(c) Tricalcium aluminate (3CaO.Al2O3) is present  11%

(d) Tetracalcium aluminate (4CaO.Al2O3.Fe2O3) is present 11%

There may be small quantities of impurities present such as calcium oxide (CaO) and magnesium oxide (MgO).

When water is added to cement, C3A is the first to react and cause initial set and It generates great amount of heat.

C3S hydrates early and develops strength in the first 28 days and it also generates heat.

C2S is the next to hydrate and it hydrates slowly and is responsible for increase in ultimate strength.

C4AF is comparatively inactive compound.

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