The properties of concrete are greatly influenced by tunnel fire.Therefore, based on ISO834 fire curve, compressive experiments were conducted to study the compressive strength variations with increasing temperatures up to 700 ℃, and the formula which shows the coupling correlation between compressive strength and temperature variation based on standing time was established.Then microstructural observations of the concrete specimens by means of scanning electron microscopy (SEM) were obtained. Results showed that the compressive strength gradually decreased with increasing temperatures. These test results can be used for accurately analyzing and investigating the behavior of concrete with different temperatures, cooling modes and standing time.
