Investigation of thermal and mechanical properties of analsim natural stone depending on high temperature and time variations

Since the beginning of civilization, natural stones have been widely used by humans for various purposes and in various engineering structures. These stones, which are divided into different categories, are generally called igneous, sedimentary and metamorphic. Due to its favorable workability and high thermal resistance, analcime stone is widely recognized as a suitable material for use in masonry structures and kiln construction. In this study, the effects of firing analcime stone, a natural zeolite in the magmatic stone category, obtained from Perşembe District of Ordu Province, at different temperatures (300°C, 400°C, 500°C, 600°C, 700°C, 800°C, 900°C, 1000°C) and for different time intervals (1, 2 and 3 hours) on the mechanical and thermal properties of the cited stone were investigated. Considering the relevant standards, pressure and bending tests were carried out to examine the mechanical properties of analcime stone, and specific heat and thermal conductivity tests were carried out to examine its thermal properties, and conclusions were drawn on the results. With the increase in test temperature, the specific heat values of both natural and fired samples increased. While the specific heat value of natural analcime stone at 30°C was 0.616, the specific heat values of the samples fired at 300°C, 400°C, 500°C, 600°C, 700°C, 800°C, 900°C, and 1000°C were 0.754, 0.679, 0.605, 0.541, 0.693, 0.499, 0.660, and 0.472, respectively. While the thermal conductivity of natural analcime was 1 W/m·K, a decrease of approximately 40% was observed after a 3-hour firing process at 300°C. In the case of firing at 1000°C for 3 hours, the thermal conductivity decreased by approximately 55.8%. In this study, the optimum compressive strength of the analcime stone evaluated was determined to be at 600°C for samples fired for 1, 2, and 3 hours. Regarding the optimum flexural strength, 600°C was identified as the peak temperature for samples fired for 1 hour. Although a slight increase in flexural strength was observed at 600°C for the samples fired for 2 and 3 hours, the overall trend indicates a decline.