Hydration characteristics and sustainability of calcium carbide slag-activated full solid waste cementitious...

Using calcium carbide slag (CCS) to replace ordinary portland cement (OPC) as an alkali activator for the preparation of full solid waste cementitious material is a green and low carbon method. This study investigates the influence of 80 °C high-temperature curing on ground granulated blast furnace slag - steel slag based supersulfated cement (GS-SSC) incorporating 0 to 20 wt% CCS. The hydration products and microstructure of GS-SSC were analysed using various microscopic techniques, assess the compressive strength and pH value development, exploring the hydration mechanism of CCS activated GS-SSC. The results indicated that the CCS could increase the alkalinity of GS-SSC, activate the pozzolanic activity of ground granulated blast furnace slag-steel slag (GGBS-SS). Compared with the control group, the CCS promote the generation of more AFt and C-(A)-S-H gels, fill the pores and microcracks of the samples, making the microstructures denser. CCS significantly increased the compressive strength of the samples under curing at high temperatures. When 10 % CCS was incorporated, the compressive strength reached 31.2 MPa at 3 d and further increased to 33.5 MPa at 7 d. Moreover, sustainability assessment results indicate that the material exhibits favorable environmental and performance sustainability under this dosage condition. It is remarkable that a higher CCS content (>10 %) has a negative effect on the compressive strength of the samples. These results provide a new approach to promote the resourceful efficient utilization of industrial solid waste and serve as a valuable reference for designing low carbon cementitious materials based on GGBS-SS.