Question

A clay mineral has liquid limit of 96% and plastic limit of 16%. Sedimentation analysis reveals that the percentage of particle finer than 0.002 mm is 40%. The most probable clay mineral would be

• A. Kaolinite
• B. Illite
• C. Montmorillonite
• D. Inadequate data

Answer 1

The correct option is C Montmorillonite

$I_p=$ liquid limit - plastic limit
$=96\%-16\%=80\%$

$\%clay=40\%$

$Activity{A}_c=\frac{I_p}{\%clay}$

$=\frac{80\%}{40\%}=2>1.25$

Soil is very active
Most probable mineral would be montmorillonite