What is plasticity index of a soil?

The plasticity index of a soil is a measure of the range of moisture content over which the soil exhibits plastic behavior. It is calculated as the difference between the liquid limit and the plastic limit of the soil. Soils with a high plasticity index are more likely to exhibit plastic behavior and be prone to shrinking and swelling with changes in moisture content.

Plasticity Index (PI) of a soil is a measure of the range of water content over which a soil behaves plastically. It is calculated as the difference between the liquid limit (LL) and the plastic limit (PL) of the soil.

The plasticity index is used to classify soils into different groups based on their plasticity characteristics. The higher the plasticity index, the more plastic the soil. Plastic soils tend to be more cohesive and can hold their shape better than non-plastic soils. However, they can also be more difficult to work with and can be more susceptible to cracking and shrinkage.