Question

How is gypsum useful in setting and hardening of cement?

Answer 1

C₃A readily combines vvith water and liberates a large amount of heat. The added gypsum retards the dissolution of C₃A by forming insoluble calcium sulpho-aluminate 3CaO.Al₂O₃.xCaS0₄.7H₂0. This reaction prevents high concentration of alumina in the cement solution which retards the early initial set of the cement