Sugar added to cement mortar
- Aaccelerates setting time and destroys the early strength
- Bdelays setting time and destroys the early strengthCorrect
- Caccelerates setting time and increases the early strength
- Ddelays setting time and increases the early strength
Solution
Concept
Retarding action of sugar
Step-by-step solution
1. Sugar is a strong retarder of cement hydration. 2. It delays setting and hardening. 3. Early strength is therefore lowered (in larger doses it can ruin the early strength).
Explanation
Sugar adsorbs on cement grains and slows hydration. The setting time is prolonged and early strength is reduced.
Why the other options are wrong
Sugar does not accelerate setting. Options with "increases the early strength" ignore that hydration is retarded.
Shortcut
Sugar = retarder.
Common mistake
Thinking all admixtures improve strength.
Correct answer: B) delays setting time and destroys the early strength