Treatment of expansive soils with quality saline pore water by cyclic drying and wetting

Expansive soils can be found in many parts of the world particularly in arid and semi-arid regions. These soils pose a significant hazard to civil engineering structures due to its high swelling and shrinkage potential. This paper presents the results of an experimental program developed to investigate the effect of cyclic drying and wetting on the swelling potential of expansive soils with various pore water qualities. Soil samples were prepared by static compaction with distilled and saline pore water solutions consisting of sodium chloride (NaCl) with 50 and 250 g/L concentrations. Soil samples were subjected to drying and wetting cycles using a modified oedometer apparatus, under a surcharge pressure of 10 kPa. Axial deformations caused by drying and wetting during various cycles were measured until shrink-swell equilibrium condition was attained. The results indicated that conducting consecutive drying and wetting causes a considerable reduction in the swelling potential of soil samples prepared with different qualities of pore water. Shrink-swell equilibrium in soil samples prepared with distilled water and 50 g/L NaCl solution was achieved after 5 consecutive cycles while soil samples with 250 g/L NaCl solution as pore water, reached equilibrium condition after approximately 3 or 4 cycles. Furthermore, the overall swelling potential for soil samples prepared with 250 g/L NaCl solution was seen to be greater compared to distilled water and 50 g/L NaCl solution respectively.