Study of Fly Ash-slag-based Geopolymer Mortar Exposed to High Temperature

Abstract Purpose: To investigate the effectof the admixtures of graphene oxide (GO) and red mud (RM) on the properties of fly ash-slag-based geopolymer mortar respectively and explore the causes of changes in the strength of geopolymers after exposure to high temperature. Methods: The orthogonal method was utilized to derive the optimum mix ratios of geopolymer mortar without the addition of GO or RM. GO at 0.05% or RM at 40% was added to the mixing ratios to study their effects on the mechanical properties of the geopolymer mortar at temperatures ranging from 25 to 900 ℃, respectively. Results: The addition of GO or RM can reduce the strength loss of geopolymer after exposure to high temperature. Conclusion: (1) The addition of GO or RM can reduce the degree of cracking of geopolymer mortar after exposure to high temperature to some extent. (1) The final strength of the geopolymer is a combination of the degree of reaction and high temperature damage. (3) The degree of sintering reaction inside the mortar specimens was more fully developed and a higher concentration of feldspar-like material was produced compared to that at the edges, which caused the interior to be grayish-black.