Behaviour of Fly ash Geopolymer at High Temperature

Geopolymer is an inorganic mineral binder in several applications an alternative to Portland cement. The driving force for the utilisation of geopolymers is their ability to consume industrial residues and by-products with the great potential to reduce mine tailings and industrial by-product piles. The study presents test results concerning the impact of high temperature on physical and the mechanical properties on fly ash geopolymers with different partial replacement of fly ash (FA) by ground granulated blast furnace slag (GGBFS). The objective of this study is to clarify the influence of high temperature up to 1000°C on the course of physical and mechanical properties changes in the further perspective to their application as passive fire protection material. Although the GGBFS addition has a very beneficial effect on the strength of geopolymer giving compressive strength over 100 MPa, at high temperature, unblended FA behaves much better. An increase in compressive strength was observed after heating at 200°C and 400°C. Moreover, at 1000°C a stage of strength recovery was observed.