Experimental study on load-bearing behavior of reinforced concrete beams incorporating plastic waste

Abstract

Plastic waste is one of the serious global issues, posing significant economic and, most importantly, environmental challenges. In particular, polyethylene terephthalate (PET) is an abundant type of plastic waste, as it has been extensively used in food and beverage packaging. PET can persist in ecosystems for centuries due to its durable and hard-to-degrade structure. Therefore, various methods have been developed for the disposal of PET waste. Among them, the utilization of PET waste in concrete is recognized as one of the effective approaches to address this problem. This study examined the effect of incorporating flake-shaped PET at 1 %, 3 %, 5 %, 10 %, and 20 % by volume on the performance of the reinforced concrete beams (RCBs) produced with CEM IV 32.5 cement. The RCBs were reinforced with Ø8, Ø10, and Ø12 steel rebars, while the impact of stirrup spacing was also studied at 16 cm, 20 cm and 27 cm. The results revealed that the RCBs with larger tension bar diameters provided a higher load-bearing capacity of 52.71 kN at a PET content of 5 %. However, at PET levels exceeding 5 %, the Ø8 diameter rebars significantly improved the toughness, ductility factors, and deformation capacity of the beams, reaching maximum values of 1,644 kN mm toughness and 11.59 ductility. Furthermore, narrower stirrup spacing, especially 16 cm, resulted in higher bearing capacity and ductility at every PET ratio. Regardless of the tension bar diameter and stirrup spacing, PET contents of 10 % and 20 % led to a reduction in load-but an increase in the deformation capacity of the beams.