Effect of Elevated Temperatures on Bond Strength of Steel Reinforcement and Concrete Enhanced with Discrete Carbon Fibers

In the case of exposing a reinforced concrete structure to accidental fire, if this structure remain standing, an assessment of its residual capacity is needed, which requires accurate information regarding the residual capacity of concrete, steel and bond between them. In the peasant work, the effect of exposing carbon- fibered reinforced concrete to elevated temperatures on its bond strength with reinforcing steel bars was investigated. An experimental program consisted of fabricating and testing of 54 pull-out cubic specimens was prepared to serve this purpose. The specimens were divided into three groups to study the effect of addition of various amounts of discrete carbon fiber on its residual bond strength and the bond strength- slip response after exposure to temperature levels of 150°C, 250°C, 350°C,450°C and 550°C in addition to the room temperature. The carbon fiber content considered was 0.0%, 0.75% and 1.0% by weight of cement. In addition to the pull- out specimens, 9 cubes having the same pull-out specimens size (3 from each concrete group mix) were tested in compression.