Bond strength of corroded reinforcements in concrete after high-temperature exposure

Abstract

Reinforcement corrosion is common in concrete structures subjected to chloride exposure. The bond behaviours between corroded reinforcements and concrete after high-temperature exposure are important in the fire damage assessment of aging concrete structures. The effects of reinforcement corrosion on the bond behaviour between concrete and reinforcements after high-temperature exposure is investigated in this paper. Corroded pull-out specimens were prepared using accelerated corrosion tests. These corroded specimens were heated in an electric resistance furnace and then subjected to pull-out tests. The test results showed that the failure mode of the pull-out specimen was affected by the degree of steel corrosion, the temperature experienced, concrete cover depth and stirrup usage. The bond behaviour was less influenced when the degree of corrosion was less than 0.05 or when the exposure temperature was less than 200 °C. The bond strength reduced significantly when the temperature was between 400 and 600 °C or when the corrosion degree was greater than 0.05. The concrete cover depth and stirrup usage also had an obvious effect on the bond strength after exposure to different temperatures, whereas these parameters had little influence on the bond strength when the experienced temperatures exceeded 600 °C. Finally, a calculation method for bond strength was proposed considering the corrosion degree and temperature.