Flexural and bond-slip responses of reinforced concrete beams containing recycled coarse aggregate and polypropylene plastic

Abstract

Reusing non-biodegradable plastic waste and recycled concrete as a substitute for natural aggregates can help alleviate the pressure on natural resources. Therefore, this study aims to incorporate polypropylene plastic aggregate (PPA) and recycled coarse aggregate (RCA) in concrete mixtures. The PPA is used as a partial replacement of RCA in reinforced concrete (RC) beams. The flexural responses and bond behaviors of RCA based PPA concrete (RPC) beams are investigated. The main variables are PPA percentages (0, 5, and 10%) and shear span to effective depth ratios (a/d = 2.13, 1.52, 1.07). Nine 1100 mm long RC beams are fabricated for bending tests, and nine 350 mm long RC beams are cast for pull-out tests. Results indicate that the ultimate moment capacity is increased by up to 28.6% for 5% PPA content depending on the beam depths, and for 10% PPA content, it is decreased by up to 15%. Ductility and toughness are increased by up to 11.7% and 113.6%, depending on the PPA contents and beam depths. Bond strength is increased by up to 16.6% for 5% PPA content and then decreased for 10% PPA by up to 37.5% depending on different beam depths. It is recommended that 5% PPA be used in concrete to improve the overall performance of the RPC beams.