Effect of Municipal Solid Waste Incineration Ash on Microstructure and Hydration Mechanism of Geopolymer Composites

The geopolymerization process is an appropriate way of disposing municipal solid waste incineration fly ash (MSWIFA), and possesses the advantages immobilizing heavy metals making full use its pozzolanic properties in manufacturing green, cementitious materials. In this study, coal (FA) metakaolin (MK) were used to prepare a geopolymer composite, with MK partially replaced by different proportions MSWIFA through alkali-activation method. microstructure hydration mechanism composites containing investigated mercury intrusion porosimetry (MIP), scanning electron microscopy (SEM), Fourier transform-infrared spectroscopy (FT-IR) tests; immobilization effect paste on metal ions was explored inductively coupled plasma-atomic emission spectrometry (ICP-AES). MIP analysis showed that addition MFARR had overall degrading pore structure matrix. When content reached maximum 35%, porosity average diameter increased 25% 16%, respectively, corresponding case without MSWIFA. However, size distribution exhibited improving trend when from 15% 25%. SEM images revealed integrity micromorphology mortar became weaker after adding microstructural compactness decreased more pores microcracks appeared FT-IR pattern study suggested all similar internal structure, consisting O-H, C-O, Si-O-Si, Si-O-Al. main component hydrated at 28 d remained dominated calcium silica-aluminate (C-A-S-H), ranged 0% 35%. Finally, ICP-AES results leaching concentrations J-40 for Cd, Cr, Cu, Pb, Zn met requirements Chinese standards.