Accelerated carbonation of MSWI fly ash as a supplementary precursor in alkali-activated materials

The supply of blast furnace slag (BFS) for alkali-activated materials (AAMs) has declined due to increased scrap recycling and BFS usage in cement industry. Sustainable supplementary precursors are urgently needed to ensure the progress of AAMs. This study treated municipal solid waste incineration (MSWI) fly ash (MFA) with accelerated carbonation (AC) to convert the waste material into suitable precursors. MFA exhibited strong CO2 capture due to the presence of slaked lime, with calcite content rising by 67 % after 6-h of AC. Heavy metal leaching was significantly reduced, with Cu and Pb leachate decreasing by 53.1 % and 73.5 %, respectively. AAM mixtures with 0-50 wt% carbonated MFA (CMFA) were tested. While CMFA slowed early structuration and altered fresh mixture properties, 10 wt% CMFA achieved comparable 28-day strength to the reference, and heavy metal leachate from hardened mortars met environmental standards. Results have confirmed CMFA is a viable supplementary precursor for AAMs.