Soil-water characteristic curve of remolded expansive soils

The state behavior of unsaturated soils is controlled in part by the soil-water characteristic curve (SWCC) and unsaturated permeability. Both these soil properties are dependent on pore geometry. The SWCC exhibits hysteresis, so the wetting and drying curves of the SWCC are different. In this paper, SWCCs of remolded Guangxi and Hefei expansive soils of varying dry densities have been measured and studied. The research shows that the shape of SWCC depends on the dry density of soil samples. The slope of soil-water characteristic curves between the air entry value point and residual water content point will be steeper when the dry density increases. The slope of the soil-water characteristic curve fluctuates for low dry density soil samples and it is stable for higher dry density soil samples. The air entry value of the soil-water characteristic curve increases with the dry density, but the variation of the residual water content is small over the dry density range considered. The SWCC characteristics are correlated to the pore structure. The authors present the volumetric water content (which is defined as the ratio of the volume of water in sample to the total volume of sample) in the sample as a parameter, normalizing a single variable for plotting the soil-water characteristic curves of expansive soil. The volumetric water content can embody the effect of water content, degree of saturation and void ratio of sample. Copyright ASCE 2006.