Statistical and Mechanical Performance Analysis of Conventional Concrete and Shredded Plastic – Modified Concrete

Abstract

In an effort to combat the global plastic waste crisis and advance sustainable building practices, this study explores the use of shredded polyethylene terephthalate (PET) as a partial substitute for granite aggregates in concrete. The mechanical and statistical performance of conventional and PET-modified concrete (0%, 2.5%, 5%, and 10% replacement) was assessed.

According to ASTM C128 material characterization, sharp sand (specific gravity 2.58, Cu = 6.0, Cc = 0.67) was suitable. ANOVA and regression analysis of the compressive and flexural strength tests revealed that low PET dosages (≤5%) produced 28-day compressive strengths of 28.13 MPa and 27.47 MPa, surpassing ASTM C39 structural thresholds, with negligible flexural strength reductions (≈2%). However, 10% PET decreased compressive strength by 71.3% to 9.16 MPa, making it unsuitable for structural use because of increased porosity and poor bonding.

ANOVA revealed that PET and granite had a significant impact (p < 0.001), and regression modelling showed that the strength decreased by 2.26 MPa for every 1% increase in PET (R² = 89.6%). Higher PET dosages are appropriate for non-structural applications, while lower dosages (≤5%) promote sustainable structural concrete. To improve environmentally friendly concrete applications, future studies should examine PET surface treatments and durability