Bond Performance between Slightly Corroded Steel Bar and Concrete after Exposure to High Temperature

Bond-slip characteristics of slightly corroded (less than 2% mass loss) reinforcing steel bars embedded in concrete were investigated with pull-out tests conducted after exposure to high temperature and subsequent cooling. Twenty-five scenarios consisting of five corrosion levels (0.0%, 0.5%, 1.0%, 1.5%, and 2.0% corrosion loss) and five exposed temperatures (20°C, 200°C, 400°C, 600°C, and 800°C) were tested. The results indicate that the slight corrosion of the reinforcement not only affects the bond performance of concrete and steel bars but also influences their reaction to elevated temperature before the exposure temperature exceeds 400°C. The effect of slight corrosion on bond-mechanics behavior was eliminated by the dramatic decrease in concrete strength and significantly different thermal expansion between concrete and steel as the exposure temperature reached 600°C.