Synchronous recycling of multi-source solid wastes for low-carbon geopolymer preparation: Primary factors identification and feasibility assessment

Exploring efficient utilization technology for solid wastes is important for the sustainable development, and the geopolymer preparation is a potential strategy for the utilization of multi-source solid wastes. However, the complex components in wastes disturbed the actual compositions in raw materials, which limited the strengthening of geopolymer and simultaneous utilizing of multi-source solid wastes. This study aims to determine the primary factors and preparation feasibility of multi-source solid waste-based geopolymer (MSWG). In this study, the geopolymer with multi-source wastes showed significant advantages in mechanical property and emission/cost reduction than that of geopolymer with unitary waste. The mechanical strength of MSWG can reach 115.77 MPa, which increased by 481.76% and 20.88% than that of unitary fly ash-based geopolymer (19.90 MPa) and blast furnace slag-based geopolymer (95.77 MPa), respectively. Meanwhile, the silicon species, aluminum species, and their connectivity forms in different MSWG were characterized and quantitatively calculated by deconvolution, which provided a feasible method for identifying the primary factors (Si-O-Al bond, Q4(3Al), Q4(4Al), and [AlO4]-Q4(4Si)) for mechanical strength. Furthermore, the composite of wastes provided more significant advantage for geopolymer preparation in emission/cost reduction, and the carbon emissions (0.261-0.315 t-CO2/t) of MSWG were reduced by 62.55%-68.90% than that of ordinary Portland cement. These results demonstrated the potential of MSWG in preparation feasibility, strength enhancement, and emission/cost reduction, and provided a feasible and cost-effective method for the simultaneously resourceful treatment of different solid wastes.