Abstract

This paper proposes an alternative use for waste such as the ash generated by coal-fired power plants and municipal incineration facilities, specifically as a raw material in alkali-activated hybrid cements. The proposal was tested by preparing a series of hybrid cements with blends of fly ash (FA) and clinker (CK) or municipal solid waste incinerator ash (MSWI) and clinker (CK) in varying proportions. Two and 28 day mechanical performance was assessed in these systems and the reaction products generated by alkaline activation were characterised using XRD and SEM/EDX. The FA hybrid cements exhibited excellent 28 day strength at very high replacement ratios (80 % FA and 20 % Portland clinker). While MSWI performance was somewhat more limited, the 28 day material containing 40 % waste reached a strength of 33 MPa, sufficient to qualify for cement category 32.5 as defined in the existing codes and standards.