Mechanical Properties of Silty Clay Stabilized with Sisal Fibers and Municipal Solid Waste Incinerator Bottom Ash Subjected to Freeze–Thaw–Dry–Wet Cycles

Abstract In cold and arid regions, climate change has exerted significant impacts on the mechanical properties of soils. Specifically, the interplay between freeze–thaw (F-T) and dry–wet (D-W) cycles profoundly influences the long-term stability of geotechnical engineering. Therefore, this study focused on mitigating the adverse effects of freeze–thaw–dry–wet (F-T-D-W) cycles on soils. Sisal fibers (SFs) and municipal solid waste incinerator bottom ash (MSWIBA) were utilized to stabilize silty clay subjected to F-T-D-W cycles. A range of multiscale experiments, including direct shear, unconfined compressive strength (UCS), and scanning electron microscopy, were performed. The influence of MSWIBA content on the mechanical properties of the SF-MSWIBA-stabilized silty clay was examined, as well as deterioration mechanisms of the soils exposed to these cycles. The results revealed that both the MSWIBA content and the number of F-T-D-W cycles had substantial influences on soil strength. After F-T-D-W cycles, the shear strength of soil samples increased with the addition of MSWIBA. Notably, soil samples containing 20% and 40% MSWIBA demonstrated excellent resistance to damage induced by F-T-D-W cycles. Furthermore, as MSWIBA content increased, both the cohesion and UCS of soil specimens first rose and subsequently declined, with peak values observed in soil stabilized with 30% MSWIBA. In contrast, the internal friction angle of soil samples displayed a trend opposite to that of the cohesion and UCS. Additionally, the optimal content of MSWIBA ranged between 26.4% and 35.9%. This study provides valuable insights into the long-term stability of silty clay in cold and arid regions, as well as the potential for using MSWIBA in such applications.