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 
Liquid limit and plastic limit 

Plasticity Index = liquid limit – plastic limit
1. Calculating Activity of Soil

Plasticity Index = 45-18 = 27

Activity = Plasticity index/(%clay content )

= 27/24.2


2. Calculate liquidity index

Liquidy Index= (Natural water content – Plastic limit)/(liquid limit-Plastic limit)