Durability of Microbial-Induced Calcite Precipitation–Treated Aeolian Sand under Freeze–Thaw Cycles

Frequent aeolian sand activities on the Qinghai–Tibet Plateau accelerate permafrost degradation, leading to vegetation loss and infrastructure damage. Microbial-induced calcium carbonate precipitation (MICP) provides a sustainable alternative to traditional sand stabilization methods. However, its resilience to freeze–thaw (F-T) cycles is not fully understood. This study examines the performance of MICP-treated aeolian sand after being subjected to 1, 3, 5, 7, and 10 F-T cycles, simulating plateau summer conditions (20°C). Postcycling assessments included surface penetration tests, simulated rainfall erosion, wind erosion resistance, and microstructural analysis. The results indicate that surface strength diminished as the number of F-T cycles increased but stabilized after the 5th cycle, retaining 2,466 kPa after 10 cycles. Samples treated with MICP displayed notably better erosion resistance than the untreated controls. After 10 F-T cycles, the cumulative mass loss under rainfall erosion was reduced by 88.8%, and under wind erosion conditions, it was reduced by 60.4%. Microstructural observations revealed that although F-T cycling induced microcracks at sand–calcite interfaces, the precipitated calcium carbonate effectively mitigated frost heave damage, thereby confirming the frost resistance of MICP-treated sand. These results indicate that MICP technology can be widely applied for sand stabilization and serve as a valuable reference for stabilizing aeolian sand. Moreover, it provides new insights into erosion mitigation in cold regions, presenting a sustainable and eco-friendly approach to combating desertification.