Concept: The Activity of the soil (A)1The activity of the soil is given by the ratio of the plasticity index ( Ip ) and the percentage of clay fraction (C) in the soil. It indicates water absorption capacity or indicates swelling and shrinkage characteristics. Activity AC=
PlasticityIndex
Percentofclayparticlesfinerthan2μm
So, C = Percentage of clay fraction finer than 2 μ