A fine-grained soil has a liquid limit of 200%, determined from the Casagrande cup method. The plastic limit was measured by rolling threads of soil to be 45%. The water content of the soil is determined to be 60% in the field by oven-drying a field sample. The clay content is 63%, determined via sieve and hydrometer testing and the plasticity chart. Determine: (a) Plasticity index, liquidity index, and the activity. (b) What state is the clay (liquid, plastic, semi-solid, etc.) and why

Since Liquidity index of soil( 0.09677) is between 0 and 0.25 and Consistency index (0.9032 ) is between 0.75 and 1; Then, The Clay is in Plastic State

Explanation:

Given that;

Liquid Limit [tex]W_{L}[/tex] = 200%

Plastic Limit [tex]W_{P}[/tex] = 45%

Natural Water Content [tex]W_N[/tex] = 60%

Clay Content [tex]C_C[/tex] = 63%;

(a) Plasticity index, liquidity index, and the activity.

Plasticity index [tex]I_P[/tex] = Liquid Limit [tex]W_{L}[/tex] - Plastic Limit [tex]W_{P}[/tex]

Plasticity index [tex]I_P[/tex] = 200% - 45%

Plasticity index [tex]I_P[/tex] = 155%

Liquidity index [tex]I_L[/tex] = [ (Natural Water Content [tex]W_N[/tex] - Plastic Limit [tex]W_{P}[/tex] = 45%) / Plasticity index [tex]I_P[/tex]]

so;

Liquidity index [tex]I_L[/tex] = ( 60 - 45)/155

Liquidity index [tex]I_L[/tex] = 15 / 155

Liquidity index [tex]I_L[/tex] = 0.09677

the activity A is;

A = Plasticity index [tex]I_P[/tex] / Clay Content [tex]C_C[/tex]

Activity A = 155 / 63

Activity A = 2.4603

b) What state is the clay;

To get the state in which is in, we use the consistency index of Soil. which is given as follows;

[tex]I_C[/tex] = [( Liquid Limit [tex]W_{L}[/tex] - Natural Water Content [tex]W_N[/tex] ) / Plasticity index [tex]I_P[/tex]]

we substitute

[tex]I_C[/tex] = ( 200 - 60) / 155

[tex]I_C[/tex] = 140 / 155

[tex]I_C[/tex] = 0.9032

Consistency index of the clay = 0.9032

Since Liquidity index of soil( 0.09677) is between 0 and 0.25 and Consistency index (0.9032 ) is between 0.75 and 1; Then, The Clay is in Plastic State