Optimization of Industrial Solid Waste Composite Solidification for Yellow River Silt: A Response Surface Approach

This study developed a composite solidification system for silt from the Yellow River Basin, utilizing calcium carbide slag, ground granulated blast-furnace slag, and desulfurized gypsum, in conjunction with the xanthan gum biopolymer. A Box–Behnken Design and Response Surface Methodology were employed, and the 14-day unconfined compressive strength was set as the focus of this investigation, with four variables examined: the content of the soil stabilizer, the xanthan gum-to-soil stabilizer ratio, the calcium carbide slag-to-soil stabilizer ratio, and the ratio of desulfurized gypsum to the soil stabilizer. The regression model demonstrated high significance (R2 = 0.9798), with the xanthan gum ratio exerting the most substantial influence on the soil strength. The optimal proportions were determined to be 4.01% soil stabilizer content, 0.080 xanthan gum ratio, 0.143 calcium carbide slag ratio, and 0.110 desulfurized gypsum ratio. Microstructural analysis revealed that xanthan gum maintained hydration humidity through hydrogen bonding, facilitating the formation of C-(A)-S-H gels and ettringite crystals. This organic–inorganic structure effectively reduces porosity, although excess xanthan gum can impede hydration. This approach advances the sustainable utilization of industrial waste and environmentally friendly stabilization of the Yellow River silt.