Silty Soil Stabilization Using Solid Waste-Based Cementitious Materials: Durability Improvement and Performance Investigation

Solid-waste-based cementitious materials have been widely applied in soil stabilization. However, their durability in practical engineering applications remains inadequate, which may lead to performance degradation and challenges for long-term serviceability. In this study, the durability of solid waste-based cementitious materials (CSD)-solidified soil was improved by adding RL and polypropylene fibers (PP). The research results indicate that the addition of RL hinders the ingress of water into the sample, which is beneficial for improving the water stability and resistance to dry–wet cycles of CSD solidified soil. The addition of PP can suppress crack propagation and effectively enhance the freeze–thaw cycle resistance of solidified soil. When the dosage of RL and PP is both 0.2%, CSD-RP solidified soil exhibits excellent durability performance. After 28 days, the water stability coefficient reached 82.8%, representing a 9.5% increase compared to the control group. After undergoing dry–wet and freeze–thaw cycles, the strength loss of the samples was 36.7% and 47.3%, which was 8.6% and 10.5% lower than that of the control group. Microscopic test results show that cyclic failure promotes the formation of pores and cracks in the sample, while the hydration products generated by the reaction of cementitious materials densify the soil. Compared with the control group, the total porosity of CSD-RP samples decreased by 2.45% and 2.19% after wet–dry and freeze–thaw cycles, further indicating that co doping of RL and PP is beneficial for reducing the degree of structural degradation of the samples.