Utilization of Waste-Based Expansive Agents for Soft Clay Stabilization

Ordinary Portland Cement (OPC) has been extensively employed to stabilize soft clay. However, OPC exhibits inefficiency in treating high water content soft clay, necessitating a high dosage of OPC and resulting in significant CO₂ emissions. Expansive agent (EA) is a cement additive that, during the hydration process, expands and fills some of the pores in the matrix. It has the potential to enhance the strength performance of OPC-treated soft clay. However, commercially available EA is currently costly and challenging to apply in cement-stabilized soft soil. In this study, EA derived from waste, including freshwater sludge (FS) and carbide slag (CS), was developed, and the feasibility of utilizing this waste-based EA in soft clay stabilization was examined. The EAs (both FS-CS based EA and commercial EA) were mixed with OPC and ground granulated blast-furnace slag (GGBS) for the stabilization of soft clay. The findings revealed that both FS-CS-based EA and commercial EA enhanced the unconfined compressive strength (UCS) of stabilized clay. FS-CS-based EA exhibited significantly better performance than the commercial EA in both OPC-stabilized clay and GGBS-stabilized clay. The strength enhancement effect of the FS-CS-based EA on GGBS-stabilized clay was significantly more pronounced than its effect on OPC-stabilized clay.