Utilization of coal gangue and waste incineration fly ash under high temperature sintering in cementitious materials: Physico-Mechanical properties and hydration products

Coal gangue (CG) and Waste incineration fly ash (WIFA) are the main solid waste in China. In order to value-added utilization of both solid waste types, while achieving effective consolidation of harmful substances in WIFA. In this study, CG and WIFA were calcined at different temperatures and blending to obtain CG-WIFA, which will be used as a substitute for cement to prepare cement-based materials. Firstly, the phase composition and microstructure of CG-WIFA were analyzed. Then, the flowability, mechanical properties, and pozzolanic activity of the mortar prepared by CG-WIFA were analyzed. Finally, X-ray diffraction (XRD), thermogravimetric analysis (TG-DTG), and mercury intrusion porosimetry (MIP) were employed to investigate the hydration degree and pore structure evolution of cement incorporated with CG-WIFA. The results showed that the roundness of CG-WIFA increased at calcination temperatures above 1000 °C, and the slump of 1200CG-20WIFA reached 225 mm, an increase of 10.8 % compared to C. The pozzolanic activities of 700CG-0WIFA and 800CG-0WIFA were measured as 70.9 % and 74.6 %, respectively. Upon compounding with 20 % WIFA, these values increased to 88.3 % and 80.2 %. The addition of WIFA accelerated the hydration reaction of C 3 S and C 2 S in the cement, and refined the pore size of the cement. • CG and WIFA are sintered under high temperature to prepare CG-WIFA as cementitious materials. • CG-WIFA can promote the massive use of CG and WIFA in sustainable cement-based materials. • The physico-mechanical properties of mortar containing CG can be significantly enhanced by the composite sintering method.