JEE Main · 2023 · 08 Apr 2023 · Shift 1 · s-Block Elements

What is the purpose of adding gypsum to cement?

(A)To facilitate the hydration of cement
(B)To speed up the process of setting
(C)To slow down the process of setting✓ Correct
(D)To give a hard mass

Answer: (C)

Solution

Gypsum (CaSO₄·2H₂O) is added to cement as a retarder to slow down the setting process. Without gypsum, cement would set too quickly (flash setting), making it difficult to work with. Gypsum controls the rate of hydration of tricalcium aluminate (C₃A), allowing sufficient time for mixing, transportation, and placement of concrete.

JEE Main · 2023 · 08 Apr 2023 · Shift 1 · Single correct option

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