Aggregates MCQ with answer and solution

Concept

Causes of bulking in sand

Formula

NONE

Step-by-step solution

1. Bulking of sand refers to the increase in its volume due to an increase in moisture content. 2. A thin film of surface moisture forms around the sand particles, pushing them apart due to surface tension. 3. Therefore, surface moisture is the primary cause of bulking of sand. Answer: D

Explanation

Bulking of sand occurs when surface moisture forms a thin film of water around each sand particle. This film creates surface tension that forces the sand particles apart, increasing the overall volume of the sand mass. As moisture content increases beyond a certain limit, the film breaks and the volume returns to normal.

Why the other options are wrong

A) Clay content affects workability and strength, not the volumetric expansion caused by surface moisture. B) Air voids represent empty spaces between aggregate particles rather than causing moisture-induced expansion. C) Viscosity is a fluid property describing resistance to flow and does not cause sand bulking.

Shortcut

Surface moisture forms a thin film pushing sand grains apart, causing bulking.

Common mistake

Attributing bulking of sand to air voids or clay content rather than surface moisture films.