Abstract
The purpose of this study was to evaluate the mechanical performance and fire resistance of a high strength polymer-modified cementitious composite, to test its ability to repair concrete tunnel structures that are in danger of collapse due to cracks or deterioration. In particular, because existing repair materials are not fire-resistant and commercial fire-resistant materials have low strength, this study was aimed at increasing the water tightness and strength of a repair material and also making it resistant to fire. In addition, this study evaluated changes in internal temperature depending on the cover thickness of repair materials to determine the optimal cover thickness at which a high strength polymer-modified cementitious composite could protect existing concrete tunnel structures from fire. Results indicated that the high strength polymer-modified cementitious composite had superior strength and water tightness than commercial fire-resistant materials and it also provided good fire resistance. The high strength polymer-modified cementitious composite required to be applied in an optimal layer thickness of at least 40 mm to protect existing structures from fire.