The Effects of Domestic Plastic Waste on Concrete Properties: Sustainable Replacement of Aggregates

Abstract

Plastic waste poses a major environmental challenge in Southeast Asia, with Malaysia as the largest contributor. Recycling offers a solution by incorporating plastic waste as a substitute material in concrete production. This approach addresses environmental concerns while promoting sustainable construction practices. This study investigates the optimal ratios of cement, water, plastic replacement, and aggregate in concrete compositions. Furthermore, it examines the influence of domestically sourced waste plastic on concrete properties. A comparative analysis is conducted between concretes with and without plastic replacement, focusing on fine and coarse aggregates. Polyethylene terephthalate (PET) plastic is utilized at replacement levels of 10% and 20% in both fine and coarse aggregates. The appropriate concrete aggregate ratio is determined based on recommendations by the Department of Environment. Various tests, including slump, density for hardened concrete, water absorption, and compressive strength, are performed to assess concrete workability. The results indicate that the density of coarse aggregate plastic concretes (DP10C, DP20C) exceeds that of fine aggregate plastic concretes (DP10F, DP20F). Additionally, coarse aggregate plastic concretes (DP10C) exhibit lower water absorption rates compared to fine aggregate concretes (DP10F) at both 7-day and 28-day curing periods. Compressive strength testing reveals that concrete replacement with coarse aggregate (DP20C) yields higher strength compared to fine aggregate (DP20F). However, the replacement of fine aggregate is limited to 10%, as exceeding this percentage drastically reduces concrete strength. In conclusion, the incorporation of plastic waste in concrete production demonstrates positive environmental effects and aligns with the concept of sustainable concrete, thereby contributing to environmental conservation efforts.