Effect of Pore Water Quality on the Mechanical Behavior of an Expansive Soil during Wetting and Drying Cycles

Expansive soils are considered a worldwide problem as they cause extensive damage to civil engineering structures. An important characteristic of expansive soils is their susceptibility to volume change due to wetting and drying. This paper presets the effect of pore water quality on the swelling and shrinkage behavior of an expansive soil during wetting and drying cycles. 33 soil samples were prepared by static compaction with various pore water qualities consisting of distilled water، sodium chloride (50g/lit) and calcium chloride (250gr/lit). Wetting and drying cycles were conducted on samples in a modified odometer apparatus under the surcharge pressure of 10 kPa using distilled water as the reservoir fluid during wetting. Results indicated that samples prepared with calcium chloride show more swelling potential compared to distilled water and sodium chloride. Furthermore swelling and shrinkage potential، specific volume and dry unit weight for soil samples reach equilibrium after 5 cycles for distilled water and sodium chloride and 3 cycles for calcium chloride.