Give a brief account of the production of cement and write its properties and uses.

(N/A) The raw materials for the manufacture of cement are limestone and clay. When clay and lime are strongly heated together,they fuse and react to form 'cement clinker'.
This clinker is mixed with $2-3 \%$ by weight of gypsum $(CaSO_{4} \cdot 2H_{2}O)$ to form cement.
Thus,the important ingredients present in Portland cement are dicalcium silicate $(Ca_{2}SiO_{4})$ $(26 \%)$,tricalcium silicate $(Ca_{3}SiO_{5})$ $(51 \%)$,and tricalcium aluminate $(Ca_{3}Al_{2}O_{6})$ $(11 \%)$.
Properties (Setting of Cement): When mixed with water,the setting of cement takes place to give a hard mass. This is due to the hydration of the molecules of the constituents and their rearrangement. The purpose of adding gypsum is to slow down the process of setting of the cement so that it gets sufficiently hardened.
Uses: Cement is a commodity of national necessity,second only to iron and steel. It is used in concrete and reinforced concrete,in plastering,and in the construction of bridges,dams,and buildings.