FLY ASH GEOPOLYMER AFTER EXPOSURE TO ELEVATED TEMPERATURE: MECHANICAL PROPERTIES AND MICROSTRUCTURE

Materials based on alkali activated alumnosilicates generally exhibit a very good resistance against exposure to high temperatures. The aim of the presented study was to determine properties of geopolymer prepared via alkali activation of type F fly ash after exposure to high temperatures. Fly ash geopolymer was subjected to temperatures in the range of 200-1200 degrees C for the period of 1 h. Post-thermal treatment test were used to determine the residual compressive and flexural strengths of thermally treated geopolymer material. The microstructural changes caused by the heat were investigated by means of mercury intrusion porosimetry, SEM, HT-XRD and FTIR analysis and the results were correlated to the mechanical behaviour.