A systematic review exploring the feasibility of waste plastic as different constituents towards sustainable concrete

Plastics have become an irreplaceable part of our daily lives due to their usefulness, low weight, and durability. Population growth and urbanization result in excessive usage of plastic products and produce huge quantities of plastic waste. However, only a small amount of plastic is properly recycled, which results in detrimental effects on ecology and the environment by the unrecycled plastic wastes. To address the larger infrastructure needs of the growing population, a huge amount of concrete is required.The basic raw materials of concrete are coarse aggregate and river sand, which have been obtained from natural resources. This constant exploitation of natural resources causes its reduction. For the past few decades, researchers have been focusing on the effective utilization of plastic waste in construction projects, which not only minimizes the raw material depletion issue but also addresses the waste plastic disposal problem to some extent. Considering an adequate PRISMA (Preferred Reporting Items Systematic Reviews and Meta-Analyses) framework for a systematic review on this topic, 174 records have been collected from databases like Scopus, Science Direct, and Web of Science and thoroughly analyzed for this investigation. The efficacy of plastic waste to be used as alternate aggregates or fibers in conventional concrete mixes has been reviewed in terms of the properties of fresh and hardened concrete. Moreover, as per the applicability, the properties of hardened plastic concrete have been assessed in terms of the mechanical and durability characteristics. The performance of plastic concrete as structural members in terms of shear and flexural strength and deflection characteristics has also been discussed in this article. Furthermore, this review article also summarizes the effect of the addition of waste plastic to conventional concrete mixes at the microstructural level. As plastic concrete exhibits low strength and certain durability issues, a number of unknown aspects regarding its applicability in infrastructure projects still exist. In line with this, this study not only summarizes the critical findings in this area but also identifies research gaps presenting future research possibilities.