Effect of cement modification on expansive soil slope

The swelling characteristic is most important for expansive soil, and it is one of the main factors that cause the disaster of expansive soil slope. After mixing with cement, the engineering behaviours of the expansive soil get improved and, in particular, the swelling characteristic basically disappears. In this paper, Nanyang middle expansive soil, which is encountered in the Middle Route of South-North Water Transfer Project, was studied on the long-term effects. The optimum amount of cement content is determined according to the free swelling ratio. The long-term improvement of swelling potential, strength and modulus are studied by laboratory tests. Based on test results, numerical modelling was used to evaluate the plastic zone development and safety of the expansive soil slope. In addition, a method to determine the thickness of cement treatment was proposed.