Road Performance and Durability of Dredged Soil Stabilized Using a Calcium Carbide Slag–GGBS–Fly Ash Binder

Dredged soil treatment and reuse remain major economic and environmental challenges in geotechnical and highway engineering. Cement-based stabilization can effectively improve the engineering properties of dredged soil, but its large-scale use is associated with high material costs, energy consumption, and carbon emissions. In this study, a solid-waste-based binder composed of calcium carbide slag (CS), ground granulated blast-furnace slag (GGBS), and fly ash (FA) was developed as a potential cement alternative for stabilizing organic-rich dredged soil in road applications. Based on mortar-performance screening, a CS:GGBS:FA mass ratio of 0.25:0.50:0.25 was selected, and the road performance and durability of the resulting CS-GGBS-FA (CGF)-stabilized soil were systematically evaluated. Laboratory tests, including California bearing ratio (CBR), dynamic resilient modulus (MR), wet–dry (W–D) cycling, and freeze–thaw (F−T) cycling, were conducted, with cement-stabilized soil used as a reference. The results showed that the CBR and MR of the CGF-stabilized soil increased significantly with binder content and curing time, meeting the requirements for subgrade and subbase applications under different highway classes. Compared with cement-stabilized soil, the CGF-stabilized soil showed slightly lower CBR and MR values at the same binder content but exhibited favorable strength retention and mass stability during W–D and F–T cycling. Overall, a CGF content of at least 8% provided sufficient strength, stiffness, and durability for road use.