Mechanical Properties of Concrete Mixture Mix Types C30 & C45 With Recycled HDPE Replacement as Coarse Aggregate

The utilization of recycled plastic in concrete production is an innovative approach that addresses both the environmental issues associated with plastic waste and enhances the properties of concrete. An experimental mixture of standard concrete (C30&C45) was made, with coarse aggregate replaced by (0,10,20,30%) for each mixture. In this study, cubes (150 mm x 150 mm x 150 mm) at 7 days and 28 days old were examined. This study assesses C30 and C45 concrete containing 10–30% recycled HDPE as a coarse aggregate substitute. The slump and unit weight diminished (slump decreased by 6.5–16%, density correspondingly), and the compressive strength declined by 8–27% at 28 days. Conversely, splitting tensile and flexural strengths were enhanced, with tensile strength rising by up to 26%, attributable to HDPE's fiber-like characteristics. The results demonstrate that HDPE improves crack resistance while reducing compressive strength, making it more suitable for non-structural or lightweight applications.