Durability of calcium-rich municipal solid waste incineration fly ash-based geopolymer to sulfate and sulfuric acid

To evaluate the feasibility and safety of municipal solid waste incineration fly ash (MSWIFA)-based geopolymer, its durability against water, 3% Na 2 SO 4 , 1% H 2 SO 4 and 3% H 2 SO 4 for 112 days was investigated. Results showed that H 2 SO 4 resistance of MSWIFA-based geopolymers was weaker than that of Na 2 SO 4 and deteriorated with increasing MSWIFA incorporation and H 2 SO 4 concentration. Under H 2 SO 4 erosion, CaCO 3 or C-A-S-H gels formed CaSO 4 ·2H 2 O, and this decalcification process caused cracks formation. Dealumination disrupted the electrostatic interaction of [AlO 4 ] - and Al-O coordination, reducing the solidification efficiency of Zn and Pb significantly. Conversely, Cu and Cr with Si-O coordination exhibited greater than 70% solidification efficiency.