Gypsum is a mineral and is hydrated calcium sulfate in chemical form.
Gypsum plays a very important role in controlling the rate of hardening of the cement. During the cement manufacturing process, upon the cooling of clinker, a small amount of gypsum is introduced during the final grinding process.
Gypsum is added to control the "setting of cement". If not added, the cement will set immediately after mixing of water leaving no time for concrete placing.
