Effects of fly ash characteristics on the mix proportion of the fly ash based geopolymer concrete

Geopolymers are an eco-friendly alternative to the Portland cement. The use of geopolymer as a binder in producing concrete contributes in reducing the emissions of the greenhouse gases due to manufacturing of the Portland cement. The geopolymer binder is produced by alkali activation of by-product aluminosilicate materials such as fly ash and blast furnace slag. The use of fly ash in producing geopolymer has gained more attraction owing to the favourable chemical composition and wide availability. However, fly ashes from different sources have different extents of chemical reactivity with the alkaline activator in the geopolymer. Hence, the use of fly ashes from different sources may lead to geopolymer binder with different performance. One of the major challenges resulted from the use of fly ash in geopolymer binder is specifying the mix proportion of geopolymer mixes using fly ashes from different sources. Therefore, it is important to understand the effect of fly ash characteristics on the selection of the mix proportion of fly ash based geopolymer mixes. This study investigates the effect of different fly ash characteristics on selecting the dosage of the alkaline activator, the optimum curing temperature and fly ash content in the geopolymer mixes. For this aim, fly ashes from five different sources; Eraring (ER), Mt-Piper (MP), Bayswater (BW), Gladstone (GL) and Collie (CL); with broadly different characteristics were used in this study...