Alkali-activated ground granulated blast-furnace slag incorporating incinerator fly ash as a potential binder

Incinerator fly ash (IFA) is the ash residual after incineration of municipal solid waste. Due to the presence of more leachable trace elements, utilization of IFA is rare. Alkali-activated GGBS has been report to possess superior heavy metal immobilization capability. This study investigated the influence of IFA addition on the mechanical strength, chemical structure, and heavy metal leaching of alkali-activated GGBS-IFA binders. It revealed that the IFA used in this study is less reactive than GGBS and has a low efficiency factor of 0.13 due to high crystallinity and low Si and Al content. Incorporation of IFA hinders the formation of gel and reduces the compressive strength of the resulting alkali-activated GGBS-IFA binder. However, even at high IFA content where 60% of GGBS was replaced by IFA, a moderate compressive strength of around 17 MPa of the resulting binder can still be obtained. Alkali-activated GGBS-IFA binders provided effective means to immobilize heavy metals. The incorporation of IFA into alkali-activated GGBS binders provides a possible measure to utilize IFA as construction materials for civil engineering applications.