Monotonic and Cyclic Behaviors of Reinforced Recycled Aggregate Concrete Beams

This study experimentally investigated the behavior of reinforced recycled aggregate concrete (RAC) beams under monotonic and cyclic loadings to identify the advantages and shortcomings of RAC in reinforced concrete beams. Five RAC specimens and one normal aggregate concrete (NAC) specimen were tested to failure. The concrete compositions of RAC and NAC were similar; however, the coarse aggregate of RAC was recycled coarse aggregate, while that of NAC was normal stone coarse aggregate. Results indicated similarities in the failure modes of RAC and NAC beams. Compared with NAC beams, the yield and ultimate load-carrying capacities of RAC beams were only 2.6% and 8.9% lower, respectively. The cyclic loading effect negligibly induced strength degradation but decreased ductility by 9.1%. However, the yield deflection and yield stiffness of RAC beams were 22.9% higher and 30% lower than those of NAC beams, revealing their shortcomings. The above results emphasized the potential use of RAC in structural members by addressing the high deformation characteristic of RAC (e.g., modifying the concrete composition to increase the compressive strength of RAC). The nonlinear analytical method of NAC beams, in which the fiber model and the finite element method were finally combined, can be used for RAC beam analysis with acceptable accuracy.