Comparative investigation on the chemical structure and rheological properties of asphalt modified with different recycled plastics

The value-added recycling of waste plastics as modifiers in asphalt could efficiently dispose of the solid waste and achieve economic modification. However, there remains a research gap in the comparison of the modification effect of various recycled plastics on asphalt. Therefore, this study illustrated the potential application of seven different recycled plastics (RPs) pellets in improving asphalt performance. The chemical structure and rheological performance of recycled plastics modified asphalt (RPMA) were investigated through the Fourier transform infrared (FTIR) test, gel permeation chromatography (GPC) test, X-ray diffraction (XRD) test and dynamic rheological test. The results showed that the recycled polyvinyl chloride, recycled ethylene-vinyl acetate, recycled polystyrene and recycled acrylonitrile butadiene styrene introduced new functional groups in RPMA, derived initially from the plastics. However, the modification of RPMA is mainly the physical process. Due to the macromolecular from RPs, it showed a significant increase in large molecules of RPMA. The crystalline structure of the binders was observably enhanced by recycled polyethylene, leading to the restriction of molecular chain movement and improvement in deformation resistance. As indicated, the incorporation of RPs increased the elastic component and stiffness, which significantly improved the deformation resistance, especially in recycled polyethylene. This study would support the selection of plastic recycling and promote the application of RPs in asphalt modifiers for sustainable materials in road infrastructure.