Utilizing residues of CFB co-combustion of coal, sludge and TDF as an alkali activator in eco-binder

Residues of co-combustion are not addressed in Taiwan standards for fly ash use in concrete. This paper presents feasibility of re-utilizing CFB co-fired fly ash (CFFA) as an alkali activator for the eco-binder of CFFA and GGBS. The optimal mixture of the binder is specimen F3S7, which reaches 31.43 MPa that is 72.4% compressive strength of OPM at 56 days. XRD and SEM showed that CFFA activated the GGBS to generate CaO, which reacted with H2O, SiO2, and Al2O3 to form C-S-H and C-A-S-H pastes. Compressive strength reduction trend for F4S6 to F7S3 started after 28 days because high SO3 content.