All-solid-waste-based non-sintered ceramsite prepared from coal fly ash and dechlorinated municipal solid waste...

Dechlorinated municipal solid waste incineration fly ash (DFA) necessitates harmless treatment due to its heavy metal leaching toxicity. In this work, an all-solid-waste-based non-sintered ceramsite (NSC) was synthesized using coal fly ash (CFA), ground granulated blast furnace slag (GGBFS), and flue gas desulfurization gypsum (FGDG) and DFA. The optimal NSC formulation (CFA:GGBFS:FGDG:DFA = 4:9:2:1) exhibited a 7-day compressive strength of 5.94 MPa, apparent density of 1911 kg/m³, 1-h water absorption of 3.12 %, and softening coefficient of 68.47 %. Its carbon emission intensity is 67.1 kg CO₂/ton, demonstrating significant environmental advantages. The hydration mechanism of NSC was investigated via XRD, FTIR, TG-DSC and SEM-EDS. Results indicated that active CaO in FGDG reacted with SiO₂ and Al₂O₃ in CFA, forming C-A-H and C-(A)-S-H gels. Broken Si-O-Al bonds generated C-S-H gels, ettringite (AFt) and monosulfoaluminate (AFm). Simultaneously, active aluminosilicates in DFA reacted with CFA components to produce AH₃. The leaching concentrations of Zn, Cr, Pb, Cu and Cd in NSC were below the limits of the Integrated Wastewater Discharge Standard (GB8978-1996). This innovative NSC preparation method not only shows promise for practical applications but also provides a novel approach for the collaborative resource utilization of solid waste.