Cement Testing MCQ with answer and solution

Concept

Vicat's apparatus finds normal consistency, initial setting time and final setting time of cement.

Step-by-step solution

1. Setting time is found by needle penetration into cement paste. 2. Initial setting: Vicat needle (1 mm square) fails to pierce the paste 5 ± 0.5 mm from the bottom of the mould. 3. Final setting: needle with annular attachment makes a mark on the surface, but the attachment does not. 4. Both tests use Vicat's apparatus. So the answer is D.

Explanation

Vicat's apparatus has different needles for consistency, initial setting time and final setting time. For OPC, initial setting time is at least 30 minutes and final setting time is at most 600 minutes.

Why the other options are wrong

A: Air permeability (Blaine) test finds fineness of cement. B: Soundness test (Le Chatelier or autoclave) finds unsoundness, which is expansion of cement. C: Sieve test finds fineness of cement.

Shortcut

Consistency and setting time = Vicat's apparatus.

Common mistake

Mixing up the soundness test (Le Chatelier) with setting time tests.