Flexural behavior of recycled aggregates concrete beams reinforced with GFRP bars

Concrete made with recycled concrete aggregate has reduced durability, increasing the risk of corrosion in embedded steel reinforcement. Replacing steel bars with glass fiber-reinforced polymer (GFRP) bars eliminates this corrosion risk but significantly affects the structural behavior of flexural members. This study investigates the flexural behavior of beams reinforced with GFRP bars and made with recycled aggregate concrete. Eight beams were tested using a four-point loading setup. The variables in the beams were the type of coarse aggregates (natural and recycled), compressive strength of concrete (32 and 55 MPa) and ratio of longitudinal reinforcement (0.5% to 1.44%). Results indicated a slight reduction in flexural strength and a considerable increase in vertical deflections due to the use of recycled concrete aggregates. However, the overall flexural behavior was not significantly affected. Comparisons between the observed results with analytical predictions showed that the ACI 440.11-22 code, the CSA S806 standard and the general flexure theory provided conservative estimates of strength for both natural aggregate concrete and recycled aggregate concrete beams. In addition, the ACI 440.11-22 code and CSA S806-12 standard provided unconservative estimates of the deflections at service load, with the CSA S806-12 standard yielding more favorable results.