Bond performance assessment of uncorroded and corroded reinforced recycled aggregate concrete

The structural performance of reinforced concrete elements is significantly influenced by the bond between steel and concrete. This study aims to shed light on the bond-slip behavior of recycled aggregate concrete with uncorroded and corroded reinforcing steel bars. The goal is to understand the potential applications of recycled coarse aggregates (RCA) from construction and demolition waste in structural concrete for real-world construction settings. For this purpose, 41 pull-out specimens were tested, incorporating different percentages of RCA (0 %, 25 %, and 50 %) along with increasing levels of corrosion (up to 10 % mass loss) in order to obtain the local bond-slip curve between steel and concrete. Bond-slip responses were analyzed to assess the impact of RCA replacement and rebar corrosion levels on bond behavior, and the results were then compared to existing models in the literature. The test results indicate that, although the compressive strength of concrete with 50 % RCA was lower than that of concrete containing only natural coarse aggregates (NCA), the use of RCA does not worsen the bond performance for uncorroded specimens, due to the enhanced tensile behavior and toughness of RCA concrete. In case of corroded specimens, a splitting failure was observed for all the mixes, so providing a lower bound for bond strength, which significantly decreased as the level of rebar corrosion increased, except at minor levels of corrosion. Tests results showed that NCA and RCA concrete exhibited similar bond capacity, with the primary difference being a slightly higher susceptibility to corrosion as RCA content increased.