Amin Soltani - MSc Student, Faculty of Soil and Water Engineering, University of Tehran
Ali Raeesi Estabragh - Associate Professor, Faculty of Soil and Water Engineering, University of Tehran
Gholamali Vakili - Geotechnical Lab Instructor, Faculty of Soil and Water Engineering, University of Tehran

This paper presents the results of an experimental program developed to investigate the effect of pore water with high salinity on the mechanical behavior of an expansive soil during consecutive drying and wetting cycles. Soil specimens were prepared by static compaction with distilled and saline (250 g/L of NaCl) pore water quality. Specimens were subjected to drying and wetting cycles using a modified oedometer apparatus under a surcharge pressure of 10 kPa using distilled water for flooding of wetting cycles. Results indicated that axial and radial deformation in soil specimens reach equilibrium after 5 and 4 consecutive cycles for distilled and saline pore water respectively. Furthermore swell-shrink paths (void ratio versus moisture content) were determined; theses paths were proven to be nearly S shaped curves which show that the majority of deformations are located between the 60% and 80% saturation lines. In addition at equilibrium condition the swell-shrink paths for saline pore water quality shows reduction in swelling potential compared to distilled water.

Expansive soil, pore water, drying and wetting cycles, swell-shrink paths