Investigation of the effect of curing and high temperature on the strength of copolymer added geopolymer mortars

Cracks that occur in geopolymer mortars under the influence of high temperature cause a decrease in strength. In this study, ethylene and methyl-acrylate copolymer-based phase change material added (5%, 10% and 15% by mass) Geopolymer mortar samples (GMS) were produced by alkali activation of slag. Samples cured at 23 °C, 50 °C and 95 °C. Flexural strength and compressive strength and Ultrasonic pulse velocity measurements were made after exposed two different high temperatures (250 °C, 500 °C) and while the samples were hot and cooled state. Due to the fact that the phase change material melts, fills the cracks and cools, it has a bridge effect, thus providing superior strength properties. The flexural strength was increased approximately 4 times by adding 15% PCM. Compressive strength of copolymer-based phase change material added GMS cured at 23 °C increased up to 169% compared to the compressive strength at ambient conditions after exposure to 500 °C. While the curing temperature of 50 °C or 95 °C does not cause a significant change on compressive strength in laboratory conditions, the compressive strength of these samples is 5 times higher than that of samples cured at 23 °C. After exposure to 500 °C, there was a 48% increase in compressive strength between cooled and hot state.