Influence of Temperature Changes Caused by Firing and Cooling on the Physical and Mechanical Properties of Travertine

In the case of explosions and fires, the rocks undergo cycles of heating and cooling, that is, they are exposed to considerable heat first and then cooled after extinguishing the fire. The purpose of this paper is to study how the temperature in a heating-cooling cycle can affect the physical and mechanical properties of travertine. In Iran, travertine stone is widely used for building facades, so travertine was chosen as the material of study. In this study, three types of travertine (Travertine B, Travertine D and Travertine R) were studied. The effective porosity and permeability at 25 °C for Travertine B is greater than Travertine D and Travertine D is greater than Travertine R. Also, the longitudinal wave velocity, tensile strength and uniaxial compressive strength at 25 °C for Travertine B are lower than Travertine D and Travertine D is lower than Travertine R. During the heating phase in a heating-cooling cycle, experiments were performed on specimens that were initially exposed to temperatures of 150, 300, 500 and 800 °C and then cooled gradually to ambient temperature. A series of experiments were performed on specimens that were not exposed to a heating-cooling cycle. This paper investigates the effect of the heating-cooling process on its physical properties including effective porosity, longitudinal wave velocity and permeability, and its mechanical properties including tensile strength and uniaxial compressive strength. The results showed that as the temperature increases, the effective porosity and permeability increased and the longitudinal wave velocity, tensile strength and uniaxial compressive strength decreased. The highest increase in effective porosity and permeability due to increasing temperature was related to travertine B and the lowest increase was related to travertine R. The highest decrease in longitudinal wave velocity, tensile strength, and uniaxial compressive strength due to increasing temperature was related to travertine B and the lowest decrease was related to travertine R.