Utilization of municipal solid waste incineration bottom ash in autoclaved aerated concrete

Abstract

The objective of this study was to assess the feasibility of application of municipal solid waste incineration (MSWI) bottom ash as a substitute of quartz sand for the preparation of autoclaved aerated concrete (AAC). Influence of substitution mass ratio and fineness of MSWI bottom ash on the physical-mechanical properties and microstructure of AAC was investigated. Leaching toxicity was also determined to ensure the environmental safety of AAC with MSWI bottom ash. The results demonstrated that the incorporation of MSWI bottom ash can reduce the gas-foaming time, compressive strength, density and thermal conductivity. Moreover, compressive strength and density of AAC increase with the increasing of fineness of MSWI bottom ash. The reactive silica in the bottom ash strongly affected the formation of tobermorite. The needle-like tobermorite in the control sample was transformed into plate-like tobermorite with the increase of bottom ash up to 40% and the crumbled foiled tobermorite and grass-like C-S-H structure formed in ACC with 100% bottom ash. It is also evident that heavy metal concentrations in the leachates of AAC and autoclaved water are far lower than recommended in the GB5085.3-2007.