Investigation into Xanthan Gum Biopolymer on Mitigating Cracking and Erosion Behavior of Soil

The soil on the slope may experience more severe erosion as a result of the surface cracks caused by desiccation. Xanthan gum (XG) was introduced to reduce the soil's tendency to erode and crack in order to increase the stability of slope soil. In this study, the microstructure and behaviors of sand-admixed soil (0%–70% sand content) with various XG contents (0.05%–0.25% by the mass of dry soil) were investigated using the desiccation cracking tests, erosion tests, and scanning electron microscope (SEM) technique. The findings showed that soil water evaporation, crack resistance, and erosion resistance are significantly influenced by sand and XG content. The initial evaporation rate increased by 15.6%, the drying time decreased by 11 h, and the surface crack ratio dropped by 11.9% as the sand content rose from 0% to 70%. The initial evaporation rate of the clay decreased by 11.1% with a 0.25% XG content, while the residual water content increased by nearly six times and there were no soil cracks. Additionally, the sand-admixed soil would not crack and the erosion significantly decreased with 0.15% XG content, demonstrating that this level of XG is the most efficient and cost-effective for controlling both cracking and erosion. Because soil contains macropores, it was discovered that higher sand content accelerates water evaporation, lowers matric suction, increases friction and fracture toughness, which prevents crack formation. Because of its potent water adsorption and pore clogging properties, the addition of XG reduced water evaporation and improved the soil's ability to hold water. Besides, due to the inter-particle bonds and formed network structure, biopolymer treatment effectively improved soil cohesion and conferred cracking resistance. The generation of preferential flow and the occurrence of infiltration, which promote the soil's antierosion ability, were also prevented by the presence of XG.