A novel low-carbon binder: Utilization of municipal solid waste incineration fly ash and flue gas desulfurization gypsum to co-activate granulated blast furnace slag

Utilization of solid wastes to prepare binder would provide great economic and environmental benefits. In the present research, granulated blast furnace slag (GBFS) is activated by municipal solid waste incineration fly ash (MSWIFA) and flue gas desulfurization gypsum (FGDG). The effect of FGDG on the properties of the ternary binder is researched, including setting time, compressive strength, and drying shrinkage. The activation process is analyzed by hydration heat, XRD, TGA, and FT-IR; the microstructure is characterized by MIP and SEM. In addition, the ecological benefit is evaluated. Results show that the compressive strength of GMF15 (70 % GBFS/ 15 % MSWIFA/15 % FGDG) is 57.2 MPa at 28 d. The presence of FGDG prolongs the induction period, resulting in the increase in setting time. The generation of ettringite is accelerated by using FGDG, leading to the decrease in porosity significantly. However, the excess FGDG is harmful to the accumulation of hydrates and the densification of microstructure. Furthermore, the leaching concentration of heavy metals, such as Cu, Zn, Cd, and Pb, is far lower than the limitation required by the related national standard; the CO2 emissions of GMF15 are reduced by 95 % compared to OPC. This research develops a low-carbon binder composed of entire solid wastes.