Soil stabilization and erosion resistance capabilities of vegetative biomaterials based on biopolymer

Conventional ecological slope protection methods predominantly rely on cement-based materials, whose strong alkalinity leads to soil compaction and poor ecological compatibility. To address these limitations, this study innovatively integrates biopolymer-based soil stabilization, plant growth promotion, and slope erosion resistance into a comprehensive research framework, evaluating xanthan gum (XG) and gellan gum (GG) as eco-friendly alternatives. Macroscopic mechanical properties were assessed through unconfined compression, direct shear, and permeability tests, while microscopic mechanisms were elucidated using scanning electron microscopy (SEM) and low-field nuclear magnetic resonance (NMR). Plant growth experiments and simulated erosion tests were conducted to quantify the synergistic effects of biopolymers and vegetation on slope protection. The results show that the addition of 2% XG and 2% GG increases unconfined compressive strength by 135% and 130%, respectively, and reduces the permeability coefficient by four orders of magnitude. Mechanistically, XG enhances soil strength via viscous particle bridging, whereas GG forms a robust gel matrix, both reducing soil porosity and refining pore structure. Both biopolymers significantly promote ryegrass growth—increasing average root length by 36.40% (XG) and 31.04% (GG)—by improving soil water retention and structure. Notably, the XG-vegetation and GG-vegetation composite systems achieve erosion rates as low as 6.50% and 4.97%, respectively, outperforming both bare slopes and slopes treated with biopolymers alone. This study pioneers a multi-performance integrated ecological slope protection technology that simultaneously optimizes mechanical stability, ecological compatibility, and erosion resistance. Unlike existing studies that focus on single functional improvements of individual biopolymers, this work emphasizes the synergistic enhancement of XG and GG with vegetation, achieving more comprehensive and practical engineering outcomes. In contrast to cement-based materials that cause soil alkalization and ecological damage, the proposed biopolymer-vegetation composite system offers a low-carbon, sustainable solution, demonstrating high potential for application in ecological restoration projects.