Carbide Slag-Driven Activation of Granulated Blast Furnace Slag/Electric Arc Furnace Slag Hybrid System: A Cost-Effective and Low-Alkalinity Cementitious Material Design

To address the resource utilization bottleneck caused by the low activity of steel slag (SS), this study investigated the influence of electric arc furnace slag (EAFS) and carbide slag (CS) on the strength of self-activated cementitious materials composed of high-calcium solid waste. A preparation method for sustainable cementitious materials was proposed, integrating low-cost materials with an environmentally friendly reaction pathway. The cementitious materials were prepared using granulated blast furnace slag from Wuhan (GBFS-W), EAFS, and CS. The hydration reaction mechanism of the cementitious materials was explored using X-ray diffraction (XRD), Fourier-Transform infrared spectroscopy (FTIR), Thermogravimetry-derivative thermogravimetry-differential scanning calorimetry (TG-DTG-DSC), and scanning electron microscopy (SEM). The results indicate that when the dosage of carbide slag (DC) was 12% and the replacement ratio of electric arc furnace slag (RS) was 20%, the optimal uniaxial compressive strengths after 3 days and 28 days of curing were 13.64 and 22.56 MPa, respectively. The early-stage hydration reaction was primarily driven by GBFS-W, and EAFS gradually participated actively as the reaction progressed. The main hydration products were Ca(OH)2, C─ (A)─ S─ H gel, and CaCO3, which formed a skeletal structure to endow the cementitious material with enhanced strength. These findings provide a process optimization pathway for developing environmentally friendly cementitious materials based on all-solid-waste self-activation. Their low-cost characteristics and strength performance can meet the requirements for large-scale applications in scenarios such as mine backfilling, dredged sludge solidification, and low-strength building components.