Effect of polyethylene terephthalate granules on nano-CaCO3-blended concrete

This study explores the effects of partially replacing fine aggregate with 10% polyethylene terephthalate granules (PET) and cement with varying amounts (0–5%) of nano calcium carbonate (CaCO3) in M40 grade concrete. Concrete mixes were tested for workability, density, compressive strength, tensile strength, and flexural strength. Microstructural characteristics were examined using Scanning Electron Microscopy (SEM) and X-Ray Diffraction (XRD), while ANSYS simulations were used to validate compressive strength results. The results indicated that the optimal performance was achieved at 2% nano-CaCO3 replacement along with 10% PET. Although workability and density slightly declined with increasing CaCO3 content, compressive and tensile strengths showed only minor reductions, reflecting the limited reactivity of CaCO3. On the other hand, the addition of PET improved flexural strength and toughness, though these benefits reduced gradually at higher CaCO3 levels. SEM and XRD analyses confirmed uniform dispersion and the presence of crystalline phases, while ANSYS simulations closely matched experimental results, reinforcing the validity of the findings. The study is limited to M40 grade concrete and specific replacement levels. However, the findings suggest that combining PET waste and nano-CaCO3 can enhance mechanical performance while contributing to environmental benefits by reducing plastic waste and CO₂ emissions. Further research is needed for broader application and lifecycle assessment.