Clinker-free binders derived from industrial solid wastes are promising for low-carbon construction, but many binder designs still rely on reagent-grade activators. This study investigates carbide slag (CS) as a substitute for a conventional alkali activator route in a waste-derived clinker-free binder composed of fly ash, coal gasification slag, and blast furnace slag. The CS-based binder is benchmarked against unactivated, mechanically processed, and Ca(OH)2-activated reference binders. The CS-based route shows sustained strength development from 3 to 28 d and achieves 20.04 MPa compressive strength at 28 d, slightly higher than the Ca(OH)2-activated reference (18.78 MPa). Mercury intrusion porosimetry reveals clear pore refinement: the fraction of pore throats ≤ 50 nm increased to 40.96% in the CS-based binder, compared with 1.50% in the unactivated milled-CGS reference, and the median pore throat decreased to 70.01 nm. Calorimetric kinetic fitting showed that the CS-based binder had a higher fitted cumulative heat release, 58.75 J·g−1, than the Ca(OH)2-activated reference, 23.36 J·g−1, indicating a more sustained reaction process. FTIR, TG-DTG, XRD, and SEM-EDS further supported differences in gel development and Ca-bearing phase evolution. In particular, the CS-based binder showed a high-temperature mass loss above 600 °C of 14.11%, compared with 5.83% for the Ca(OH)2-activated reference, and a stronger relative calcite signal. These results show that CS substitution is not equivalent to simple Ca(OH)2 addition and provides binder-scale evidence for designing waste-derived clinker-free binders with reduced reliance on reagent-grade activation.
Li et al. (2026) studied this question.