Multiple choice

Gypsum is added to Portland cement to

  1. accelerate the process of setting

  2. harden it

  3. retard the process of setting

  4. improve hydratability

Reveal answer Fill a bubble to check yourself
C Correct answer
Explanation

Gypsum (calcium sulfate dihydrate) is added to clinker during the manufacturing of Portland cement to control the setting time. Without gypsum, the cement would react with water and set almost immediately, preventing proper mixing and placement.