Investigation of physical and mechanical properties of zeolite-based geopolymer mortars under the effect of high temperature

In this study, mortar samples were produced by activating natural zeolite with different amounts of Sodium Hydroxide (NaOH). Standard sand was used as aggregate in the study. Mortar samples were obtained using zeolite, NaOH, water and standard sand. The zeolite used in the study was activated with NaOH containing 10%, 12%, 14%, 16%, 18% and 20% sodium (Na) by weight. After the produced mortar samples were placed in standard molds of 40×40×160 mm3 dimensions, they were cured at 90°C for 24 hours. Then, unit weight, compressive and flexural strength and ultrasound pulse velocity of the samples were measured. Samples were prepared for high temperature (300°C, 600°C and 900°C) tests from zeolite samples with the same weight ratios, and the unit weight, compressive, flexural strength and ultrasound pulse velocity rates of the samples were measured. The data obtained showed that all geopolymer mortars lost strength under the influence of high temperatures. It was observed that this loss rate was maximum at 900°C, while the least strength loss was observed at 300°C.