Stress-Dependent Soil-Water Characteristic Curves of Lime-Treated Expansive Clay

Abstract

Proper understanding of the field performance of lime-treated expansive soils requires the evaluation of their unsaturated properties under stress conditions similar to that in the field. This paper studied the influence of net vertical stress on the soil-water characteristic curves (SWCC) of lime-treated expansive clay. The first phase of this study investigated the influence of lime content and curing period under low net vertical stress (7 kPa) using axis translation and filter paper techniques with simultaneous measurements of sample volume change. The second phase evaluated the SWCCs of untreated and lime-treated clays under vertical stresses of 100 and 600 kPa. Different representations of SWCCs were considered in the interpretation of test results. Test results indicated that lime content had a significant effect on the shape and air entry value of SWCCs because of changes in soil microstructure, whereas curing period had a far less significant effect. Furthermore, the application of net vertical stress delayed the desaturation of samples causing increase in air entry value. On the basis of plots for the variation of void ratio versus suction, the increase in air entry value was attributed to considerable reduction in volume (void ratio) associated with the application of the net vertical stress causing samples to remain saturated up to high suctions levels.