How is the plasticity index calculated?

The calculation of the plasticity index is conducted by taking the difference between the liquid limit and the plastic limit of a soil sample. The plasticity index provides a measure of the plasticity of the soil, which indicates how it behaves under varying moisture conditions. Specifically, the plasticity index is defined as:

Plasticity Index (PI) = Liquid Limit (LL) - Plastic Limit (PL)

This index offers valuable information regarding the consistency and workability of the soil, with higher values typically indicating a wider range of moisture content over which the soil remains plastic.

Understanding this calculation is crucial for engineers and technicians when assessing the suitability of soil for construction and other applications, as it helps in characterizing soil behavior under different conditions. Other options suggest different methods of calculation or factors that are not relevant to the standard definition of the plasticity index, which is specifically focused on the differences between moisture limit measurements rather than averages or sums.