The liquidity index (LI) is used for scaling the natural water content of a soil sample to the limits. It can be calculated as a ratio of difference between natural water content, plastic limit, and liquid limit: LI=(W-PL)/(LL-PL) where W is the natural water content.
Activity of soil can be defined as ration of plasticity index to clay fraction as percentage.
Data given
Liquid Limit (LL)=45%
Plastic Limit (PL)=18%
Clay content=24.2%(particle <2 micro meter)
moisture content is 29%
Liquid limit and plastic limit
Plasticity Index = liquid limit – plastic limit1. Calculating Activity of Soil
Plasticity Index = 45-18 = 27
Activity = Plasticity index/(%clay content )
= 27/24.2
=1.115
2. Calculate liquidity index
Liquidy Index= (Natural water content – Plastic limit)/(liquid limit-Plastic limit)
=(29-18)/(45-18)
=11/27
=0.407
