EFFECT OF HIGH TEMPERATURE ON BOND BETWEEN STEEL REINFORCEMENT: The effect of elevated temperature on the bond strength between steel reinforcement and Fiber reinforced high strength concrete

Bond behavior between steel reinforcement and fibre reinforced concrete under elevated temperature of up to 700 ºC is evaluated using prismatic double pullout (DP) specimens. Five different high strength concrete (HSC) mixtures (with and without fibers) were prepared using basalt aggregate at a w/c ratio of 0.35. All specimens were cured for 28 days in a controlled temperature-water bath at a degree of 40 ºC. Then specimens were subjected to heating by an electrical furnace. Pullout specimens were tested under pullout to evaluate the bond behavior between steel reinforcement bars and surrounding concrete mixtures before and after heating. Cubes (100mm) cast from same mixture, cured, and heat-treated under similar conditions were also tested to evaluate compressive and splitting strength. The results showed marked reductions in residual compressive, splitting and bond strengths of HSC under exposure temperatures. DP concrete specimens with fibers showed better bond behavior than that of HSC. This was represented by higher residual bond strength, and steel-bond ductility. Mixture incorporated H-steel fibers imparted the highest concrete-steel bond resistance against high temperatures