Question

A lab technician finds water content of clay soil test specimen when the two parts of soil in Casagrande’s liquid limit test apparatus close at 25 drops to be 55%. The water content of the same soil when he rolls out to 1/8 inch diameter on a glass plate crumbles is 24%. Determine the following:

- Liquid Limit

- Plastic Limit

- Plasticity Index

- Classify soil in accordance with Plasticity Chart.

Answer 1

Cassagrande's Test is conducted for determining the liquid limit and 25 number of blows of cup cup indicate the liquid limit of soil. Hence, Liquid Limit = 0.55

Plastic Limit is defined by the water content of soil when it begins to crumble when rolled into threads of 1/8 inches. Hence, Plastic Limit=0.24

Plasticity Index is given by difference between two limits= LL- PL = 0.55-0.24 =0.31

In accordance with the said charts soil can be classified as CH, clayey soil with high plasticity