A novel foaming additive derived from waste polyethylene terephthalate (PET) for low-carbon warm mix asphalt

Plastic pollution is growing relentlessly due to the careless disposal of waste plastic products. This study focuses on converting waste plastic bottles into a foaming additive for the production of eco-friendly warm mix asphalt (WMA) for paving purposes. The additive, namely PET-TETA, was synthesized from waste polyethylene terephthalate (PET) via an aminolysis process. Its chemical and physical properties were characterized by the scanning electron microscope (SEM), X-ray diffractometer (XRD), and thermogravimetry-differential thermal analyzer (TG-DTA) tests. The WMA mixtures were prepared using PET-TETA and a commercial foaming additive, and their properties were studied and compared to a conventional hot mix asphalt mixture. The performances of the asphalt mixtures were characterized through the indirect tensile stiffness modulus, moisture susceptibility, and immersion Hamburg wheel-tracking tests. The findings revealed that PET-TETA was a semicrystalline material containing approximately 26 % hydration water, which could be released gradually during the preparation of asphalt pavements. The performance of the WMA mixture utilizing PET-TETA was comparable to the other two asphalt mixtures, and it exhibited higher strengths and better resistance to stripping. Therefore, it is promising to apply PET-TETA as a sustainable and effective WMA additive for paving purposes, providing a solution to the issue of waste plastic disposal.