Flexural bond behavior of reinforced recycled aggregate concrete

Replacing natural aggregate concrete with recycled aggregate concrete (RAC) can effectively solve aggregate shortage problems. However, application of recycled aggregate in engineering structures requires analysis of the interaction between steel bars and RAC. The bond behavior under flexure is similar to the actual state of stress in structural members. 15 beam specimens were designed and tested to investigate the RAC-reinforcement bond behavior and the constitutive relationship at the interface between them. Test parameters include water-binder ratio, recycled coarse aggregate (RCA) replacement percentage, recycled fine aggregate (RFA) replacement percentage, bar surface shape, and anchorage length of reinforcements. The influence of the above variables on the load to slip curves, bond strength, and the bond efficiency coefficient is discussed. Bond strength between reinforcements and concrete decreases with increasing RCA replacement percentage, however, the rate of decrease is reduced for specimens with low water-binder ratio. The addition of RFA significantly degrades bond behavior. The bond strength between deformed reinforcements and RAC is approximately 2 times of that of plain reinforcements. With increasing anchorage length, the interface bond behavior between the reinforcements and RAC decreases. (C) 2019 Published by Elsevier Ltd.