The GATE Grind

GATE 2021 CE (CE1) – Question 15

Construction Materials · Cement: hydration, admixtures · 1 mark · Multiple choice

Gypsum is typically added in cement to

  1. prevent quick setting
  2. enhance hardening
  3. increase workability
  4. decrease heat of hydration

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Show answer and explanation

Correct answer: (A) prevent quick setting

Explanation

Without gypsum, tricalcium aluminate reacts rapidly with water and can cause flash setting. Gypsum supplies sulfate, forming an ettringite layer that regulates this early reaction. Its primary purpose is therefore to **prevent quick setting (A)**.