Incinerator bottom ash (IBA) aerated geopolymer

With extremely low density and thermal conductivity, aerated concrete is an ideal material for thermal insulation and sound-proofing. The introduction of gas in aerated concrete is achieved usually by the use of finely divided aluminum powder. The aluminum reacts with the soluble alkalis in the cement slurry to generate small bubbles of hydrogen. In this paper, municipal solid waste incinerator bottom ash (IBA) is used as the aerating agent and geopolymer precursor to create aerated geopolymer. Effects of liquid-to-solid ratio, concentration of alkaline solution, and mixing duration on the physical and the mechanical properties, microstructure, and heavy metal leaching of the resulting IBA aerated geopolymer are investigated. The results showed that the utilization of IBA to synthesize aerated geopolymer with low density is feasible. Microstructure analysis indicated successful geopolymerization through alkali activation of IBA and new crystal phase consisted of sodium, aluminum, and silica was identified. The leaching test showed geopolymerization can effectively immobilize the majority of trace heavy metal elements in IBA.