Experimental Study on Strength Characteristics of Expansive Soil Improved by Steel Slag Powder and Cement Under Dry-Wet Cycles

Expansive soil, as an unsaturated cohesive soil, is considered a harmful geological soil due to its tendency to expand with water and shrink with loss of water. Especially in the alternating environment between dry and wet (D-W) cycles, it can cause engineering accidents because of its deformation. Steel slag powder (SSP) was used as a new curing agent to improve the expansive soil by combining cement. The variation rules of strength characteristics of improved expansive soil were studied under the condition of the D-W cycles. Through the laboratory test, the unconfined compressive strength (UCS) characteristics of the expansive soil (ES) and improved expansive soil (improved by cement (Es-C) and by steel slag powder and cement (Es-SSP-C) and by steel slag powder and cement and NaOH (Es-SSP-C-N)) were studied under different curing age and different D-W cycles. The testing results show that the strength of improved expansive soils increases with the curing time. The strength degradation of Es-SSP-C-N samples was the least when they have performed the D-W cycles, which indicates that Es-SSP-C-N is a good method to improve expansive soil in the D-W circulation environment.