Enhancing the thermal performance of Class F fly ash-based geopolymer by sodalite

Class F Fly ash-based geopolymers are prone to various high-temperature phenomena, such as cracking, spalling, and thermal shrinkage. Here we study the effect of enriching fly ash with synthetic sodalite phase in order enhance properties formed geopolymer. The morphological changes, compositional alterations porosity, gel behaviour, on deformation material after exposure up 1000 °C investigated by a multiple-analytical approach. Results indicate that adding 5 wt% enhances considerably performance inducing formation, including anorthoclase, wollastonite, leucite. Besides, sodium-bearing phases lowered glass transition temperature, thanks formation mixed K-Na phase. Moreover, shrinkage at high temperature is substantially reduced addition sodalite, suggesting its function skeletal reinforcement.