Use of Municipal Solid Waste Incinerator (MSWI) Fly Ash in Alkali Activated Slag Cement

This paper investigates the utilization of municipal solid waste incinerator fly ash (MFA) as a replacement of alkali-activated slag (AAS) cement. The mechanical performance of pastes with different dosages of MFA were studied and optimized. Compared with the AAS no MFA added, the compressive strength of the AAS pastes prepared at 3 d(days) with a 10% replacement of MFA fell sharply from 71.11 to 48.25 MPa, which remained stable with more MFA added. When the replacement proportion increased to 30%, the AAS pastes still reached a high compressive strength of 64.37 MPa at 28 d. XRD and SEM analysis were conducted to investigate the hydration products and micro structure of pastes. Main hydration products of the AAS paste with 30% MFA addition were calcium silicate hydrate (C-S-H) gel and C-A-S-H (C-CaO; A-Al₂O₃; S-SiO₂; H-H₂O) gel. Some unreacted MFA particles could be also observed from SEM analysis. This study provides a new resource utilization way of MFA.