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

Abstract

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.