Definition of fat clays
It is fine grained soil. Fat clays are cohesive and compressible in nature with high plasticity and liquid limit of 50 or greater. It is symbolized as CH. Such type of clays contains high proportion of minerals that make it greasy to the feel.
What are problems associated with Fat Clays?
Fat clays have microscopic mineral grains that are especially attractive to water. It and absorb water and begin the swelling process. Once the swelling begins, it can lift floor due to pressure build-up.
The formation of surface cracks, moisture infiltration through these cracks into the clay resulting reduction in suction and shearing resistance of the clay. Such phenomena cause slope failures in high-plasticity clays.