Gypsum is a mineral that is hydrated Calcium Sulphate(CaSO4.2H2O) in chemical form. It plays an essential role in controlling the rate of hardening of cement. During cement manufacturing, a small amount of gypsum is introduced during the final grinding process after the clinker has cooled.
If too much gypsum is included it leads to disruptive expansions of the hardened paste or concrete.
Functions of the gypsum
- Gypsum prevents cement from setting immediately after water is added, it gives more time for concrete to be placed. If it isn’t added, the cement immediately sets and there is no time left for concrete placing.
- Gypsum increases the strength and hardness of cement.
- Gypsum helps grind clinker by preventing the powder from sticking to the surface of the mill wall and balls.
