Experimental Study on Engineering Properties of Guilin Red Clay Improved by PASS Composite LBG

To improve the engineering properties of red clay, sodium polyacrylate (PAAS) and locust bean gum (LBG) were used as modifiers, either singly or in combination. The modified soils were subjected to variable head permeability tests, triaxial compression tests, and scanning electron microscopy (SEM) tests to analyze the effects of different modifiers on the permeability and shear strength of the red clay and systematically explore the modification mechanism. The results showed that both PAAS and LBG significantly reduced the permeability of the red clay, with PAAS having a more pronounced effect. This mechanism is attributed to PAAS swelling upon water absorption, forming a hydrogel network that fills micropores and forms ionic bonds with clay particles. LBG, on the other hand, encapsulates the particles in a highly viscous colloid, enhancing their aggregation. Regarding shear strength, both PAAS and LBG improved soil cohesion, with PAAS exhibiting a superior combined improvement in cohesion and internal friction angle compared to LBG. The PAAS-LBG composite modification exhibits a significant synergistic effect: PAAS forms a continuous hydrogel network as the primary skeletal structure of the soil, while LBG supplements the pores and increases bonding, resulting in a denser soil structure. Microscopic analysis further confirms that the PAAS-LBG composite modification significantly reduces porosity and enhances interparticle interlocking, thereby simultaneously improving both the impermeability and shear strength of the red clay. This research can provide a reference for sustainable development and red clay modification in red clay regions.