Effect of Glutinous Rice Slurry on the Unconfined Compressive Strength of Lime-Treated Seasonal Permafrost Subjected to Freeze-Thaw Cycles

Abstract

It is important to account for the poor ecological environment of weak seasonal permafrost regions while developing a suitable ground improvement technique. As an organic non-polluting material, glutinous rice slurry improves the unconfined compressive strength of the soil through induction and synergy with lime. The Qinghai-Tibet Plateau has cold weather, large temperature differences between day and night, and a fragile ecological environment. Once damaged, it is extremely difficult to recover. This study investigates the effects of glutinous rice slurry on the unconfined compressive strength (UCS), failure mode, and microstructure of lime-treated seasonally frozen soil subjected to freeze-thaw cycles. Organic glutinous rice slurry with concentrations of 0, 2, 4, 6, and 8% was added to soil specimens that were treated with 10% lime and subjected to 0, 1, 3, 6, and 10 freeze-thaw cycles. In tests, the addition of glutinous rice pulp could increase the UCS of the soil by up to 40%. The first freeze-thaw cycle has the greatest impact on the UCS of the soil sample, with a decrease of 6–15%. Glutinous rice slurry can reduce the degradation effects of freeze-thaw cycles by increasing the contact area between soil particles. In a comprehensive evaluation under test conditions, a glutinous rice slurry concentration of 4% led to optimal results. It revealed the change characteristics of the microstructure under the action of freeze-thaw cycles, which has a good corresponding relationship with the macroscopic mechanical properties. The results can provide reference value for the application of glutinous rice slurry in the modification of subgrade soil in seasonal permafrost areas.