Microstructural evolution and direct shear strength of cement-stabilized soil under freeze-thaw cycles

Extensive research has demonstrated that cement is one of the most effective materials for improving soil properties. Researchers have investigated cement-stabilized soil techniques from various perspectives, including microstructural evolution and mechanical performance. However, studies on cement-stabilized soils in seasonal frozen regions remain limited. This study thus explored the application of cement-stabilized soil in these regions, specifically examining the effects of freeze-thaw cycles on its microstructure and shear strength through scanning electron microscopy (SEM) and direct shear tests. The findings indicate that freeze-thaw cycles induce noticeable microcracks and pores, significantly increasing particle breakage and decomposition, which leads to a loose structure and severely compromises the soil's mechanical properties. Incorporating cement generates hydration products that form cementitious bonds between soil particles, significantly enhancing structural density and overall stability. This cement stabilization effectively mitigates the damage caused by freeze-thaw cycles, enabling the soil to maintain good shear strength even after such cycles. These findings underscore the importance of cement stabilization in improving soil performance under freeze-thaw conditions, providing a theoretical basis and technical support for foundation improvement in cold regions.