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GATE 2020 CE (CE1) – Question 18

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

As dicalcium silicate ($C_2S$) content in cement clinker increases, heat of hydration ______.

  1. increases
  2. decreases
  3. initially decreases then increases
  4. does not change

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Correct answer: (B) decreases

Explanation

C2S hydrates more slowly and releases less heat than the more reactive C3S phase. Increasing its proportion lowers the heat of hydration under the intended clinker comparison. **Answer:B**. This is why higher C2S content is associated with low-heat cement.