Gypsum (CaSO4.2H2O) is added to clinker during cement manufacturing to

Gypsum (CaSO4·2H2O) is added to cement clinker primarily to act as a retarding agent. During the hydration process, cement components like tricalcium aluminate (C3A) react rapidly with water, which can lead to 'flash setting' or immediate hardening. Gypsum reacts with C3A to form ettringite, which creates a protective layer around cement particles, thereby slowing down the initial hydration reaction. This effectively decreases the rate of setting of the cement, providing sufficient time for mixing, transporting, and placing the material in construction projects. Without gypsum, the cement would set too quickly to be workable. While it indirectly supports strength development by ensuring a gradual hydration process, its specific functional role in the clinker grinding stage is to regulate and prolong the setting time.