Variations in Soil Water Characteristic Curves of Lateritic Soil Treated with Bentonite

Soil water characteristic curve (SWCC), which defines a soil's ability to store and release water as it is subjected to various soil suctions, is an important tool to estimate and interpret unsaturated sol property functions. The purpose of this study was to estimate SWCC data for lateritic soil - bentonite mixtures proposed as a barrier material in waste containment systems. Also, the effect of various compaction states, namely dry, optimum and wet moisture conditions, using standard Proctor energy on SWCCs of the mixtures was examined. The SWCCs were measured in the laboratory by sequential desorption of saturated compacted lateritic soil — bentonite mixtures using pressure plate extractors. The experimental SWCC data were fit to the Brooks — Corey and Van Genuchten parametric equations. Variations in SWCCs due to higher bentonite contents reflected in the fitting parameters of the two equations. For example, higher air entry pressures (Ψ) were obtained for mixtures containing higher bentonite content when compacted wet of optimum water content.