Soil Classification MCQ with answer and solution

Concept

USCS classifies soil by the type and predominance of its constituents, considering grain size, gradation, plasticity and compressibility.

Formula

C_u = D₆₀ / D₁₀, C_c = (D₃₀)² / (D₁₀ × D₆₀)

Step-by-step solution

1. USCS looks at grain size, gradation, plasticity and compressibility. 2. Check the options: grain length, elasticity and non-compressibility are not used. 3. Gradation is one of the factors used. 4. So the answer is (B).

Explanation

The Unified Soil Classification System groups soils based on grain size, gradation, plasticity and compressibility. Gradation (well or poorly graded, checked by C_u and C_c) is one of these factors. So gradation is the correct choice.

Why the other options are wrong

A: USCS uses grain size, not grain length. C: USCS uses plasticity, not elasticity. D: USCS uses compressibility, not non-compressibility.

Shortcut

Remember the four USCS factors: size, gradation, plasticity, compressibility.

Common mistake

Mixing up plasticity with elasticity, or grain size with grain length.