Microstructural and strength evolutions of geopolymer composite reinforced by resin exposed to elevated temperature

The microstructural and strength developments of alkali-activated metakaolin (MK)/granulated blast furnace slag (GBFS) based geopolymer reinforced by resin were studied after exposure to elevated temperatures. The XRD and SEM results indicated that the geopolymer and composite maintained original structure characteristics and did not have any new crystalline phase generated at elevated temperatures from 150 to 600 °C, while new crystalline phases and morphology deterioration occurred at 850 °C. The incorporation of a little amount of resin was able to improve effectively the compressive and flexural strengths of geopolymer. The geopolymer composite was via a thermal reaction mechanism of free water evaporation, dehydration in matrix, resin pyrolysis and new phase generation after exposure to elevated temperatures from 150 to 850 °C. A small amount of volume shrinkage demonstrated that the geopolymer and composites showed remarkable heat resistance.