Plasticity Index
The degree of plasticity is obtained from the water content of the soil at the liquid limit wL [ASTM D4318-10], and is as per [DIN18196:1988] and [DINENISO14688:2001], divided into:
|
Low plasticity |
wL < 35 % by weight |
|
Medium plasticity |
35 < wL < 50 % by weight |
|
High plasticity |
wL > 50 % by weight |
The plasticity index, IP, is used in order to achieve a clear distinction of the cohesive soil type into silt or clay, as well as in silty or clayey behaviour of fine components in a type of soil with mixed grain sizes. The plasticity index is defined as the difference between the water content at the liquid- and plasticity limit:
