Performance of fly ash-based geopolymer mortar

Abstract

This study has investigated the joint effect of several mix parameters on the properties of foam geopolymers. The mix parameters analysed through a laboratory experiment of 54 different mortar mixes were, sodium silicate/sodium hydroxide mass ratio (2.5, 3.5, 4.5), activator/binder mass ratio (0.6, 0.8, 1.0), chemical foaming agent type (hydrogen peroxide (H2O2) and sodium perborate (NaBO3)) and foaming agent mass ratio content (1%, 2%, 3%). Properties, SEM and FTIR analysis and cost analysis are included. The results show that the sodium perborate over performs hydrogen peroxide leading to a lower overall thermal conductibility of foam geopolymers. The use of an activator/binder ratio of 0.8 a sodium silicate/sodium hydroxide of 2.5 led to the lowest thermal conductivity. Mixtures with a low thermal conductivity of around 0.1 W/(m.ºK) and a compressive strength of around 6 MPa were achieved. The cost analysis show that the foaming agents are responsible for a small percentage of foam geopolymers total cost (less than 10%) being that the alkaline activators are responsible for more than 80%