Question

What conclusion can be drawn if a Kaolinite clay soil has a Plastic limit of 15.36, the liquid limit of 47.8, plasticity index of 32.44 and natural water content is 11.35? It is also calculated that the liquidity index is -0.1236. This is a result of a lab experiment. Since there is a contradiction between high plasticity of soil but negative liquidity index, so I am so confused about it. Thank you.

Answer 1

Liquidity index represents natural behavior of soil and it is defined as

Where wn is natural water content and wp is plastic limit

Ip is plasticity Index

IL is liquidity index

Plasticity index can tell about behavior of soil but liquidity index is represent natural behavior of soil in natural condition.

However plasticity index can high even after liquidity index is negative because plasticity index is the difference of Liquid limit and plastic limit and it can be high or low but liquidity index depend on natural water content plastic limit and plasticity index.

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