Soil Classification MCQ with answer and solution

Concept

Each USCS soil group has typical compressibility, permeability and shear strength. Fine-grained CH clay is very different from clean sand and gravel.

Step-by-step solution

1. Recall the typical properties of USCS groups. 2. GP (poorly graded gravel): very low compressibility, pervious, good shear strength. 3. SW (well graded sand): negligible compressibility, pervious, excellent shear strength. 4. SC (clayey sand): compressibility is low to medium, permeability is semi-pervious to impervious, shear strength is good. 5. CH (fat clay): high compressibility, impervious, fair to poor shear strength. 6. In row IV, CH is shown as pervious with excellent shear strength. Both are wrong. 7. Row IV is the clearly false row.

Explanation

CH is a highly plastic, fine-grained clay. It is very compressible and almost impervious. Its shear strength is poor to fair, not excellent. So row IV is false.

Common mistake

Thinking high compressibility means high permeability. In clays, high compressibility goes with very low permeability.