Fire Resistance of Strengthened RC Members Using NSM CFRP Bars with a Cladding Layer

Adhesives are fundamental materials in reinforced concrete (RC) members. Depending on the type of adhesive, the fire resistance of these members will vary. However, previous studies have focused on organic adhesives, although inorganic adhesive and hybrid organic-inorganic configurations may provide certain advantages. In the research presented in this paper, the mechanical properties of carbon fiber-reinforced polymer (CFRP) bars with an inorganic mortar cladding layer were studied experimentally. Then, fire tests were conducted on near-surface-mounted (NSM) CFRP-strengthened RC beams. The results indicated that the bars still exhibited satisfactory mechanical properties after high-temperature exposure due to the protection of the inorganic mortar cladding layer. The fire resistance of RC beams filled with fiber polymer mortar was better than that of RC beams filled with modified acrylic emulsion mortar. The hybrid organic-inorganic configurations in the NSM FRP-strengthened RC structures were feasible. Considerable fire resistance may be achieved without applying fire protection along the entire length of the beam.