Effect of silica fume and waste rubber on the performance of slag based geopolymer mortars under high temperatures

In this study, the high temperature resistance of slag based geopolymer mortars was investigated and the effect of silica fume (SF) and waste rubber (WR) on this resistance was determined. In slag based geopolymer mortars activated using 12M NaOH solution, 0, 5 and 10% by weight SF was substituted for slag. 0, 5, 10 and 15% WR by volume was substituted for fine aggregate. After the samples that completed their curing period were exposed to temperatures of 250, 500 and 750 ºC for 1 hour, the mechanical (compressive, flexural and splitting tensile strengths and impact resistance), physical (weight change and sorptivity) and microstructure (scanning electron microscopy (SEM)) properties of the samples were examined. As the SF substitution increased, the mechanical and physical properties of the samples increased, while the mechanical and physical properties of the samples decreased with the WR substitution. While the SF substitution had a positive effect on the high temperature resistance of the samples, the WR substitution had negative effect. It is thought that the choice of geopolymer binder as a binder in mortars and the use of waste tires as aggregate contribute to the literature in terms of both preventing environmental pollution and ensuring the recycling of these materials. Keywords: Slag, geopolymer mortar, high temperature resistance, silica fume, waste rubber