Reactivity of MSWI-fly ash in Mg-K-phosphate cement

0577640 - ÚTAM 2024 RIV NL eng J - Journal Article
Bernasconi, D. - Viani, A. - Zárybnická, Lucie - Mácová, Petra - Bordignon, S. - Das, G. - Borfecchia, E. - Štefančič, M. - Caviglia, C. - Destefanis, E. - Bernasconi, A. - Gobetto, R. - Pavese, A.
Reactivity of MSWI-fly ash in Mg-K-phosphate cement.
Construction and Building Materials. Roč. 409, December (2023), č. článku 134082. ISSN 0950-0618. E-ISSN 1879-0526
Institutional support: RVO:68378297
Keywords : municipal solid waste fly ash * magnesium phosphate cement * waste reactivity * stabilization/solidification
OECD category: Materials engineering
Impact factor: 7.4, year: 2022
Method of publishing: Limited access
https://doi.org/10.1016/j.conbuildmat.2023.134082

In this study, the behaviour and reactivity of Municipal Solid Waste Incineration Fly Ash (MSWI-FA), introduced in the formulation of magnesium potassium phosphate cement (MKPC), was investigated by considering the waste either as fully inert or reactive. MSWI-FA induced structural and compositional modifications in MKPC as a consequence of dissolution/precipitation processes which involved many MSWI-FA elements (e.g., Ca, Mg, Al, Si, Zn) and led to the formation of mostly amorphous phosphate secondary products. The reaction path has been described in terms of the early fast dissolution of MSWI-FA, with precipitation of very low solubility phases, and subsequent late precipitation due to pH changes and water subtraction during MKPC gelification. The increase in amorphous content peaked to 50 wt.% and it has been related to the improved behaviour with respect to the leaching of heavy metals (reduced by 70-99%), pointing to this cement as an excellent matrix for their chemical stabilization. The obtained MKPC microstructure exhibited better mechanical performance, with an improvement of up to 60% in compressive strength. All in all, the results indicated that the incorporation in MKPC is a viable recycling opportunity for MSWI-FA, although, for an effective cement formulation, its reactivity must be taken into account.
Permanent Link: https://hdl.handle.net/11104/0346770