Aggregates MCQ with answer and solution

Concept

In IS 383, Zone-IV sand is the finest grading zone. For it, 80% to 100% should pass the 600 micron sieve.

Step-by-step solution

1. IS 383 divides fine aggregate into Zone I to Zone IV, from coarse to fine. 2. The 600 micron sieve is the key sieve that decides the zone. 3. The percent passing 600 micron is: Zone I 15-34, Zone II 35-59, Zone III 60-79, Zone IV 80-100. 4. So for Zone-IV sand, 80% to 100% passes the 600 micron sieve. 5. Answer is B.

Explanation

Zone-IV is the finest sand, so most of it passes the 600 micron sieve. As per IS 383, the limit is 80% to 100%. Very fine sand like this is often used for mortar and plaster.

Why the other options are wrong

A: 40-100% is the 600 micron limit for masonry mortar sand in IS 2116, not Zone-IV. C: 0-15% is a typical limit for the 150 micron sieve. D: 70-100% is a typical limit for the 1.18 mm sieve.

Shortcut

600 micron passing: Zone I 15-34, II 35-59, III 60-79, IV 80-100.

Common mistake

Confusing the IS 2116 masonry mortar sand grading (40-100% at 600 micron) with the IS 383 Zone-IV limit.