Question

Consider the following statements:
1. Poorly graded or uniform sands compact to low dry unit weights.
2. Heavy clays with high plasticity have very low maximum dry unit weight.
3. In clay soils, the maximum dry weight tends to decrease as plasticity increases.
Which of these statements is/are correct?

• A. 1, 2 and 3
• B. 1 and 2 only
• C. 2 and 3 only
• D. 3 only

Answer 1

The correct option is A 1, 2 and 3

(a)
Poorly graded or uniform sand compact to low dry unit weights while well graded sand compact to high dry weights because in well graded soil, smaller particle can be fitted in voids of large size particle, so voids are less and this results into a dense mass.
As the plasticity increases, smaller size clay particles increases. This results in decrease in maximum dry unit weight and increase in OMC