Experimental and numerical analysis on the utilization of combined chemical and soil binder in sandy soil stabilization for mechanical and microstructural enhancement

Abstract Sandy soils are widely distributed worldwide but are often constrained in geotechnical applications due to their high permeability, low cohesion, and poor load-bearing capacity. This study evaluates the combined stabilization effect of a chemical additive (TX-95) and a soil binder (SB-95) on improving the mechanical and microstructural performance of sandy soils. Laboratory investigations, including unconfined compressive strength (UCS) and California bearing ratio (CBR) tests, were conducted with varying SB-95 contents under a constant TX-95 dosage and multiple curing periods. The results demonstrated substantial enhancement in strength, with UCS values increasing up to 893 kPa and CBR values rising from 21% to 278%. Through iterative testing, an optimal mixing and curing method was identified that maximized homogeneity and strength gain while minimizing material waste. Scanning electron microscopy revealed that the optimized process produced dense interparticle bonding through binder films and silane-based bridges, leading to a compact and cohesive soil matrix. Finite element analysis (PLAXIS 3D) further validated the experimental outcomes, showing improved stress distribution and deformation resistance of the treated subgrade. The findings confirm that the combined use of TX-95 and SB-95, coupled with the optimized preparation technique, offers an efficient stabilization strategy for sandy soils, making them suitable for durable road subgrades, embankments, and structural foundations.