Performance of glass powder substituted slag based geopolymer concretes under high temperature

Geopolymer concretes provide advantages in terms of recycling waste materials. Geopolymer concretes are advantageous in terms of both limiting the use of Portland cement and recycling waste materials. In this study, 5 different geopolymer concrete mixture groups were prepared by replacing slag with 0.5%, 10, 15 and 20% by weight glass powder (GP). Geopolymer concrete samples prepared by using 12 M sodium hydroxide solution as an alkali activator were cured in the laboratory environment. The samples, which completed their curing pe-riods, were kept at 150, 300, 450, 600 and 750 C temperatures for 1 h. Compressive strength, weight change and sorptivity values of these samples were determined. These results were interpreted together with the visual inspections and microstructure analyzes (SEM and EDS) of the samples. As the GP substitution rate increased, the mechanical properties of geopolymer concretes decreased. However, GP improved the performance of geo-polymer concretes exposed to high temperatures. Cooling in air affected the samples less negatively than cooling in water. While the Ca/Si ratios of the samples decreased at 450 C and above, the Si/Al ratio increased.

Automated summary

Geopolymer concretes offer advantages in terms of recycling waste materials. The addition of glass powder improves the performance of geopolymer concretes exposed to high temperatures. However, as the substitution rate of glass powder increases, the mechanical properties of geopolymer concretes decrease.