An experimental study on the thermal property of concrete under the load ratio condition in tunnel fire

Under the fire, the strength of concrete decreases due to the rapid temperature increase. The ratio of the axial force under the temperature increase is a major factor in deformations of concrete structures. This study has been conducted to evaluate fire performance of the concrete lining by various fire conditions under the constant loading. The specimens are prepared according to the small scale test method in EFNARC (Specification and Guidelines for Testing of Passive Fire Protection for Concrete Tunnels Linings). To analyze the thermal properties by the strength, the adopted strengths of the specimens are 24MPa, 40MPa and 50MPa. The loading ratios are 20% and 40% of the each concrete compressive strength. MHC fire is used to study the thermal impact of the concrete by rapid temperature increase. Under the same loading ratio, the 50MPa specimen shows more cracks and spalling as time goes on as compared with the specimens of 24MPa and 40MPa.