Mechanical Properties and Accumulated Plastic Strain of Calcium Carbide Residue–Silica Fume–Improved Silty Clay Under Freeze–Thaw Cycles

In order to explore the feasibility of using calcium carbide residue (CCR) and silica fume (SF) materials to reinforce silty clay roadbeds in seasonal frozen regions and seek reasonable approaches for CCR and SF treatment, this study proposes a CCR-SF cementing agent to stabilize silty clay in seasonally frozen regions. Based on the compressive and flexural strength of CCR-SF mortars, the soil is stabilized with a CCR/SF dosage ratio of 50∶50. The effects of CCR-SF dosage and curing time on the compressive strength and deformation characteristics of stabilized soil were studied through unconfined compressive strength tests. The influence of freeze–thaw cycles and dynamic load loading cycles on the accumulated plastic deformation of CCR–SF–stabilized soil was investigated through dynamic triaxial tests. The results show that the mechanical and deformation performance of silty clay is significantly improved, with the strength of CCR–SF–stabilized soil increased by about 3.9 times compared to untreated soil. There exists a critical mass fraction of CCR-SF (20%) in the stabilized soil, and when the mass fraction of CCR-SF exceeds 20%, the mechanical performance decreases instead of increasing. The accumulated plastic deformation of CCR–SF–stabilized soil increases with the number of freeze–thaw cycles and loading cycles. Within the first 1,000 loading cycles and 9 freeze–thaw cycles, the accumulated plastic deformation of stabilized soil increases rapidly. Finally, a predictive model for accumulated plastic deformation of CCR–SF–stabilized soil considering freeze–thaw cycles is established, which can provide a reference for settlement prediction of CCR–SF–stabilized soil roadbed under cyclic dynamic loads and for roadbed design and dynamic stability assessment based on strain control principles.