Effect of waste PET strips as reinforcement in concrete under cyclic loading

Reuse of waste PET bottles in construction industry is emerging as a potential option for improving the properties of unreinforced concrete. Although earlier studies have explored the effect of PET reinforced concrete under monotonic loading, limited studies have explored its behaviour under cyclic loading. In this context, the present study quantifies the impact of PET strips on characteristics of concrete under low frequency cyclic loading at different stress levels. A comparative assessment of stress–strain response, deformation characteristics, loading/unloading modulus, Poisson’s ratio and strain energy density for PET macro-reinforced concrete has been performed with conventional concrete (CC). PET concrete exhibits higher loading capacity, lower variability, delay in damage propagation and better damage tolerance under cyclic loading. The study also proposes a simple equation for quantification of confinement effect developed due to the presence of PET strips in concrete. Overall, the utilization of waste PET in concrete presents a sustainable approach for improving the properties of unreinforced concrete (viz., pavement application, flowable fill application, brick manufacturing), while reducing the negative environmental impact of waste PET.