Solidification of Nansha soft clay using cement-based composite curing agents

Solidifying Nansha soft clay using environmentally friendly curing agents can reduce the disturbance to and destruction of the ecological environment. Cement is a key factor for curing Nansha clay and an effective mass fraction of 20% is used in a single application. This study explored environmentally friendly curing agents that can be used to improve the strength of Nansha soft clay on site. Mixing 15% cement with lime, gypsum or bentonite decreased the apparent pore content and average pore diameter of the soil and increased the values of the mechanical properties. Mass fractions of lime, gypsum and bentonite of 3%, 1·5% and 3%, respectively, were found to be effective in engineering applications. Gypsum had a greater impact on shear strength than lime and bentonite, whereas lime affected the compressive strength to a greater extent. The mechanical strength and curing efficiency of soil treated with 18% cement, 3·0% lime, 4·0% gypsum, 2·0% bentonite and 1·0% caustic soda were twice those of soil cured with 25% cement, while the apparent pore content and average pore diameter were 70% lower. Another multi-component curing agent (18% cement, 3·0% lime, 4% gypsum, 3% bentonite and 0·8% caustic soda) was found to produce the highest strength and curing efficiency and thus can be considered the optimal cement-based composite curing agent for the solidification of Nansha soft clay.