Expansive Soil: Identification & Mitigating Techniques

Expansive soils are highly problematic as they have a tendency to increase in volume on absorption of water and to shrink on evaporation of water. On absorption of water the density of these soils decreases and they become slushy; they become hard on evaporation of water due to increase in density. The volumetric change in these soils is attributed to seasonal variations in the ground water profile resulting in changes in the moisture content (Rees and Thomas, 1993). The entire stratum of expansive soil in the field may not be active, as most soils do not respond quickly to climatic changes. During summer, polygonal shrinkage cracks appear near the surface, extending to a depth of about 2m, indicating a high potential for expansion and contraction (Mohan, 1977). The depth of cracking indicates the depth of active zone in which significant volume changes occur because of high moisture deficiency (Snethen, 1980).