Bond behavior between recycled aggregate concrete and deformed bars under uniaxial lateral pressure

This paper investigates the bond behavior of deformed bars embedded in recycled aggregate concrete (RAC) subjected to uniaxial lateral pressure. Sixty pull-out specimens with different levels of recycled coarse aggregate (RA; i.e. 0%, 30%, 50%, 70% and 100%) were manufactured, and then these specimens were submitted to test the bond-slip curves under different levels of uniaxial lateral pressure (i. e. 0, 0.1fcu, 0.2fcu, and 0.3fcu). The effects of lateral pressure and RA content on bond strength, peak slip, residual bond strength and bond energy density were analyzed; the bond-slip relationship between RAC and deformed bars was also established. The results demonstrated that the bond strength of reinforced RAC is comparable with that of reinforced natural aggregate concrete (NAC). It is feasible to adopt RA in structural application but the bond ductility should be improved before it can be reliable reused. With the incremental of lateral pressure, the peak slip, relative bond strength and the bond energy density gradually increased, while the relationship between these parameters and RA content could not be clearly observed. In addition, the parameter value for descending bond-slip curve was abruptly decreased after lateral pressure was applied, demonstrating that the lateral pressure increased the bond ductility of RAC specimens.