Abstract
Numerous studies conducted on different soils had focused on evaluating the drying Soil-Water Characteristic Curve (SWCC); however, in some applications measurement of wetting soil-water characteristic curve is equally important. SWCC determination for expansive soils provides an additional challenge due to volume changes that samples undergo due to change in water content. This paper aims to present the results of an experimental program developed to investigate the SWCC of a highly expansive soil under wetting and drying cycle. SWCC determination was carried out using axis translation technique. In addition, the effects of sample saturation procedures on SWCC were investigated by considering two saturation methods: free swell and preload method under optimum and dry of optimumwater content conditions. The results revealed that saturation procedures had a significant effect on drying SWCC (mostly represented in saturated water content and air-entry value). At high suction (i.e., > 0.4MPa), the effect of saturation method and initial molding conditions tend to diminish. Significant hysteresis has been noticed between drying and wetting soil-water characteristic curves due to air entrapped inside soil pores during drying path and inelastic volume changes during drying and wetting SWCC path. Effect of saturation procedures was more pronounced in the case of drying-SWCC, whereas in the wetting path the difference was less markable.