Room temperature alkali activation of fly ash: The effect of Na2O/SiO2 ratio

Alkali activation of fly ash can be considered as one of the more promising alternative systems to traditional hydraulic binders, particularly if the process can be carried out at room temperature. With the aim to find the best solution chemistry for room temperature activation, two types of fly ash have been activated using varying amounts of activators ranging Na2O/SiO2 molar ratio from 0.12 to 0.20. It was found that the behaviour of the resultant geopolymer and mortars at the fresh and hardened state is more influenced by the types of fly ash, and in particular by their fineness and mineralogical composition, then by the increasing of sodium silicate solution in the mix