Abstract: The Atterberg Limits and consolidated drained direct shear tests were performed on soil samples prepared from Ningming expansive soil slurries. This paper presents the effect of NaCl solutions on the strength parameters of Ningming expansive soils. The results indicate that, with the increase of Nacl concentrations, both the internal friction and the cohesion in the sample decrease. The liquid as well as the plastic index also decrease with the increase of NaCl concentrations. The reason for these changes might be explained from the point of NaCl solutions change the interactions among the clay particles and double electronic layer properties.

Key words: NaCl Solutions, Sample Preparation from Slurry, Shear Strength, Atterberg Limits