Co-disposal of municipal solid waste incineration bottom ash (MSWIBA) and steel slag (SS) to improve the geopolymer materials properties

Abstract

In previous studies, municipal solid waste incineration bottom ash (MSWIBA) exhibited low compressive strength when made into geopolymer materials due to the lack of active Ca. The introduction of steel slag (SS) not only supplements MSWIBA with active Ca, but also enables further treatment of SS, an underutilized solid waste. In this study, mechanical properties, XRD, TGA, FTIR and MIP are the means to evaluate this binary geopolymer. The heavy metal leaching concentration of this geopolymer was used as a basis for assessing its environmental impact. The results show that the introduction of SS helps to improve the compressive strength of geopolymers. The introduction of SS supplements the active Ca and promotes the production of C-(A)-S-H gels. Increasing the alkali doping on this basis contributes to the dissolution of active substances in MSWIBA and SS and promotes the generation of silica-aluminate gels, which likewise contributes to the development of compressive strength of geopolymers. The activation of MSWIBA by alkali can be used as an aluminum removal process, which can reduce the volume of harmful pores in the geopolymer. The solidification efficiency of heavy metals after the introduction of SS can be>90%.

Keywords: Geopolymer; Heavy metals; Municipal solid waste incineration bottom ash; Pretreatment; Steel slag.