Combined effects of cooling rate and salt on physical properties of yellow sandstone collected from Eastern China

摘要

Yellow sandstone is a widely used natural building stone that undergoes a number of changes when subjected to high heat sources. Therefore, this study considers the effect of high temperatures on some properties of yellow sandstone. For this purpose, yellow sandstone samples were exposed to temperatures of 25, 300, 400, 500, 550, 600, 700, and 800 degrees C and then rapidly cooled in water with various saline concentrations at 0 degrees C. The major findings are as follows: as temperature increased, the brightness L* and b* of color decreased, and the value of a* increased. Additionally, with increasing temperature, the surface roughness of sandstone increased approximately linearly, while the thermal conductivity decreased gradually with temperature and then decreased rapidly at 500 degrees C due to thermal damage. Moreover, thermal cracks appeared on the sandstone surface due to thermal damage. The thermal cracks in the sandstone first increased at temperatures of 400-600 degrees C and then decreased above 600 degrees C. At 600 degrees C, the cracks connected and formed a trap network. In addition, from analyzing the surface mesoscopic changes of the sandstone, it was found that the crystallization of salt solution on the sandstone surface also diminished the increase in roughness and the decrease in thermal conductivity to a certain extent.