Enhancing surface cracking and erosion resistances in lateritic soil with eco-friendly surface spraying agents

Lateritic soil slopes are prone to desiccation cracking and surface erosion, particularly in the early stages of vegetation establishment, which compromises their long-term stability and resilience. This study aims to address these issues by applying an optimized environmentally friendly agent using the surface spraying method. A series of laboratory tests were conducted to examine the effects of various potential agents on the tensile strength, desiccation cracking, surface erosion, and plant growth in lateritic soil. Finally, the protective mechanism of the optimal agent was analyzed. The results show that untreated lateritic soil at its natural dry density has a low tensile strength of 15.1 kPa after drying, resulting in a high crack intensity factor of 8.30% after wet-dry cycles and a large erosion ratio of 2.92 g/cm² under heavy rainfall. Soil stabilizer, sodium silicate, and alkaline lignin are effective in enhancing strength, mitigating cracks, and controlling erosion at appropriate concentrations, but they inhibit plant growth in lateritic soil. Polyaluminum chloride improves tensile strength and crack resistance without inhibiting plant growth, but it cannot prevent surface erosion. Polyacrylamide exhibits the best overall performance as it can increase the tensile strength to 57.7 kPa, reduce the crack intensity factor to 3.44% and the erosion ratio to within 0.10 g/cm2, without affecting plant growth. Given its accessibility, cost-effectiveness and rapid action, polyacrylamide stands out as the superior surface spraying agent for protecting lateritic soil slopes.