Effect of Admixtures on Selected Properties of Fly Ash-Based Geopolymer Composites

Featured Application The aim of this work is to increase knowledge of the use of admixtures in geopolymer composites. This research was carried out to expand our knowledge of the effects of different admixtures on the properties of fly ash-based geopolymer composites. Three admixtures were used: a liquifying admixture based on stabilized polycarboxylates, a plasticizing admixture, and a liquifying admixture based on modified polynaphthalenes. The effect of variable activator content relative to the binder was also tested. The most favorable flexural and compressive strengths as well as water absorption were obtained in the series with a liquifying admixture based on stabilized polycarboxylates and an activator to fly ash ratio of 0.5 or 0.6. An increase in flexural and compressive strengths of 11% and 32%, respectively, was obtained compared to the series without admixtures. No positive effect was found for plasticizing admixtures or those based on modified polynaphthalenes.