Synergistic Performance and Reaction Mechanisms of a Carbide Lime-Powdered Glass Composite for Soil Stabilization

Carbide lime (CL) and powdered glass (PG), as industrial by-products, possess significant potential as eco-friendly soil amendment materials. This paper presents a systematic investigation into the effectiveness and reaction mechanisms of a composite material comprising CL and PG for stabilizing dispersive soils. A systematic experimental program was designed with varying CL (0.5-6.5%) and PG (4-16%) contents, along with curing ages of 1, 7 and 14 days. Macroscopic properties, including dispersibility and permeability, were evaluated through pinhole, mud ball, and permeability tests, while phase composition and microstructural evolution were analyzed using X-ray diffraction (XRD) and scanning electron microscopy (SEM). Results demonstrate a pronounced synergistic effect between CL and PG at optimal ratios: soil dispersibility is markedly improved when CL ≥ 2.5% and PG ≥ 8%, non-dispersive behavior is achieved at all curing ages with CL between 4.5 and 6.5% and PG between 4 and 16 permeability coefficient decreases significantly with increasing material content; for instance, increasing CL from 2.5% to 6.5% (at 16% PG) reduces the permeability coefficient by over 50%. Microstructural analysis reveals that CL supplies Ca²⁺ and an alkaline environment, whereas PG provides reactive SiO₂ and Al₂O₃. Their interaction facilitates ion exchange and pozzolanic reactions, leading to the formation of C-S-H and C-A-S-H gels. These cementitious products effectively fill pores and bond soil particles, thereby enhancing structural stability. This study confirms that the CL-PG composite is an efficient and sustainable soil stabilization material. It provides novel insights into the synergistic mechanisms and optimal dosage range, offering valuable theoretical and practical guidance for the resource utilization of industrial by-products in geotechnical engineering.