Effect of Water Quality on the Swelling Properties of an Expansive Soil During Wetting and Drying Cycles

Expansive soils swell and shrink periodically when subjected to seasonal water content changes. As a result, they are a constant source of problem in the design and construction of foundations. In this study, the behaviour of an expansive soil was studied through a number of experiments involving cycles of wetting and drying using three different water qualities. Laboratory tests were performed on statically-compacted samples of an expansive soil in a modified Oedometer under constant surcharge pressure of 10 kPa. Vertical deformation of the soil sample was recorded continuously, and during the test, void ratio and water content of the sample were determined at different stages. The results indicated that the equilibrium condition was reached after about six wetting-drying cycles. It is shown that the swelling potential changes with changes in water quality; the saline water reduced the swelling potential of the soil compared to the distilled water during wetting and drying cycles. Furthermore, the results showed that the variations of water content-void ratio paths during wetting-drying were the same (no hysteresis) when the equilibrium condition was achieved