Multiscale Mechanisms of Hydrogel‐Induced Structural Stabilization and Erosion Resistance in Slag‐Amended Soils

ABSTRACT Mine slag soils exhibit poor structural stability due to their lack of clay and organic matter. This study evaluated an eco‐friendly binder (SJP)—a polyvinyl alcohol/sodium alginate‐modified glutinous rice‐derived hydrogel—for improving aggregate stability in slag‐amended soils. Surface electrochemical characterization, including surface potential, specific surface area (SSA), and cation exchange capacity (CEC), combined with extended DLVO‐based net interparticle force calculations, revealed a critical threshold at 50% slag content, beyond which surface activity collapsed and particle interactions became predominantly repulsive. SJP overcame this limitation through an organic–inorganic cementation network, as confirmed by scanning electron microscopy (SEM): apparent porosity was reduced by 41.7%, and loose point‐to‐point contacts were replaced by stable surface‐to‐surface cementation. At an optimal dosage of 0.8%, SJP stabilized the mean weight diameter (MWD) at approximately 2.7 mm across variable ionic concentrations and slag contents, and reduced rainfall‐induced splash erosion by up to 60.9% under high kinetic energy conditions (rainfall height of 1.5 m). Multi‐scale correlation analysis further confirmed that MWD was significantly and negatively correlated with splash erosion rate across all treatment conditions ( p < 0.01), demonstrating a coherent process chain from micro‐scale cementation to macro‐scale erosion resistance. These results demonstrate that SJP provides a rapid, robust, and environmentally compatible strategy for restoring the structural integrity and erosion resistance of mine‐impacted soils.