Question 3.14: The laboratory tests on a sample of soil gave the following ...

(a) Plasticity index, $I_{p}=w_{l}-w_{p}=62-28=34 \%$

Liquidity index, $I_{l}=\frac{w_{n}-w_{p}}{I_{p}}=\frac{24-28}{34}=-0.12$.

(b) Activity, $A=\frac{I_{p}}{\% \text { of particles }<2 \mu}=\frac{34}{23}=1.48$.

(c) Comments:

(i) Since $I_{l}$ is negative, the consistency of the soil is very stiff to extremely stiff (semisolid state).

(ii) Since $I_{p}$ is greater than 17% the soil is highly plastic.

(iii) Since A is greater than 1.40, the soil is active and is subject to significant volume change (shrinkage and swelling).