To address the dual challenges of solid waste disposal and low-carbon construction, this study developed an innovative controlled low-strength material (CLSM) composed entirely of industrial by-products. By utilizing calcium carbide residue (CCR) as an alkali activator for ground granulated blast furnace slag (GGBS) and fly ash (FA), the research investigated the impacts of varying the binder (GGBS-FA) content (10%, 15%, 20%, 25%) and the ratio of iron tailings sand to construction waste soil (0:10, 1:9, 3:7, 4:6, 5:5). Unconfined compressive strength (UCS) testing, X-ray diffraction (XRD), and scanning electron microscopy with energy dispersive spectroscopy (SEM-EDS) were employed for evaluation. The results indicated that across various sand-to-soil ratios, the UCS generally increased with higher binder content. Specifically, under a high mix proportion of 25% GGBS-FA content and a 4:6 sand-to-soil ratio, the 28-day UCS reached a peak of 5061.13 kPa. At a fixed GGBS-FA content, the UCS exhibited a trend of initially decreasing and subsequently increasing as the sand-to-soil ratio rose, reaching a minimum at a ratio of 3:7. For instance, within the 25% GGBS-FA group, the 3-day UCS decreased from 2031.26 kPa at a 0:10 ratio to a minimum of 940.30 kPa at 3:7, before rebounding to 1525.30 kPa at 5:5. Microstructural analyses confirmed that CCR supplied Ca 2+ and a highly alkaline environment, which facilitated the dissolution and polymerization of the GGBS-FA system. This process promoted the "bridging" effect of hydration products such as calcium alumina silica hydrates (C-(A)-S-H) and AFm across the pores, densifying the matrix and thereby enhancing both macroscopic and early-stage strength. Ultimately, this study demonstrates that this 100% waste-derived CLSM eliminates reliance on traditional cement while achieving superior mechanical performance. It offers a sustainable, high-value pathway for solid waste utilization and significantly advances the engineering application of green, low-carbon geotechnical materials.
Teng et al. (Mon,) studied this question.