Effect of Wetting-Drying on a Stabilized Expansive Soil

Abstract

In this paper, the hydro-mechanical behavior and shear strength parameters of an expansive sand-bentonite mixture under wetting and drying cycles were investigated. Sand-bentonite mixture with different percentages of bentonite prepared at different water contents (ωc) from the compaction curve was considered to examine the effects of expansive minerals and initial water content on the swelling potential, the swelling pressure, and the hydro-mechanical behavior of expansive soils in the one-dimensional consolidation test. Furthermore, potassium silicate (PS) was introduced as a stabilizing agent to remediate the expansive soil. Various PS percentages were added to improve the mixture. The response of the treated soil was studied under free-swelling test, wetting and drying cycles, one-dimensional consolidation test, and direct shear test. The results showed that adding PS to the expansive soil significantly reduced swelling and shrinkage behavior of the soil under wetting and drying cycles, especially for drying induced shrinkage. Besides, increasing the percentage of stabilizer up to 12% reduced the swelling and shrinkage potential of the expansive soil. More importantly, the agent improved the shear strength parameters of the mixture. The results showed that adding 6% (by weight) of PS increased the internal friction angle of the mixture by 11° from 34° to 45° after 48 h curing time. However, PS had no significant effect on the mechanical behavior of the expansive soil under the one-dimensional consolidation test.