Comparison of shear behavior of normal and recycled aggregates beams strengthened with CFRP U-Wraps

Abstract

In recent years recycled aggregates, from construction demolition waste, has been used as a replacement to normal (natural) aggregates in concrete. This is to preserve the depletion of natural resources and to further reduce carbon footprints in terms of energy depletion and waste disposition. Mechanical properties, such as compressive and tensile strengths, of recycled aggregates concrete (RAC) have been investigated by several researchers and were compared with that of normal aggregate concrete (NAC). In this investigation, the shear strengths and modes of failure of RAC and NAC beams have been investigated. In addition, the behavior of RAC and NAC beams strengthened with carbon-fiber-reinforced-polymer (CFRP) U-wrapped laminates have been examined. Four RAC and NAC shear-deficient rectangular beams were cast, two of which were strengthened in shear with CFRP U-wraps. The beams were tested to failure under four-point bending. The test results indicate that the shear capacity of all specimens strengthened with CFRP composites increased significantly compared to the control beam specimens. The performance of the RAC and NAC beams before and after strengthening were compared. It was observed that the RAC specimens provided similar shear strength as that of the NAC beams. The percentage increase in the shear capacity of RAC beams reached almost 60% of the control beam for the beams with U-wraps. The ACI 318-19 and ACI440.2R-17 codes are also used to predict the shear strength of the tested RAC and NAC beams and it was observed that the predicted capacities were close to the experimentally measured ones.