A comparative study on effects of fly ash and fly ash based geopolymer on the fire and mechanical properties of glass fibre reinforced epoxy composite

The effect of the incorporation of fly ash (FA) and fly ash based geopolymer (FAG) on the fire, thermal and mechanical properties of glass fibre reinforced epoxy composite were investigated. Composites containing different weight percentages of fillers (5, 10, 15, 20 and 25 wt%) were fabricated using hand lay-up and vacuum bagging techniques. The experimental results showed that both additives proved to be beneficial to the fire retardancy of the composite with the FAG system exhibiting better fire retardancy than that of the FA system. It was evidenced that both additives acted through a condensed-phase flame retardance mechanism where char formation increased when using these additives. Both additives mostly provided detrimental effects on the mechanical properties of the composite with the FA system having a lower impact on the decrement. It was also evidenced that both additives reduced the interfacial adhesion between the fibre reinforcement and the matrix indicated by the increase of fibre pull-out.