Performance test and effect evaluation of guar gum-stabilized loess as a sustainable slope protection material

During the rainy season, many slopes are eroded by precipitation on the China Loess Plateau (CLP). Hence, Guar gum (GG) is used to stabilize the topsoil of loess slopes to control rainwater erosion. To test the engineering performance of GG-stabilized loess and its feasibility in slope protection practice, the mechanical and hydraulic properties of specimens with different GG contents were measured in the laboratory. The results show that GG can effectively improve loess mechanical behavior during shear and disintegration and endow loess with good impermeability and water retention ability. With increasing GG content, the cohesion initially increased and subsequently decreased, the disintegration rate and permeability coefficient decreased, and the height of soil–water characteristic curve increased. When the GG content was 1.0%, the comprehensive engineering performance of the treated specimens was optimized. The cohesion, residual water content, and Van Genuchten (VG) model empirical fitting parameter increased by 125.7%, 148.9%, and 34.5%, while the disintegration rate, permeability coefficient, and VG model scale parameter decreased by 84.3%, 84.1%, and 80%, respectively. According to the scanning electron microscopy images, the stabilization mechanism of GG on loess relied on the hydrogel adhesion of soil particles and pore filling. Finally, field model test was used to verify that the GG-stabilized loess had excellent vegetation growth status and erosion control effect. After 120d of natural rainfall, the vegetation coverage increased by 67.6%, and the cumulative erosion decreased by 47.5%. Thus, utilizing GG-stabilized loess as a slope protection material shows great potential and is expected to promote the green construction of engineering and the sustainable development of soil and water conservation in the CLP.