High-Temperature Performance of Recycled Low-Density Polyethylene-Modified Asphalt Binder Reinforced with Thermally Treated Polyacrylonitrile Fiber

Global shift toward green construction has resulted in an increased focus on the use of recycled plastic waste for asphalt binder modification. However, there are some performance issues still associated with the recycled plastic-modified binder. In this study, the viscoelastic behavior of recycled low-density polyethylene (LDPE)-modified asphalt binder reinforced with thermally treated polyacrylonitrile (PAN) fiber was investigated. The duration of the fiber thermal treatment was optimized at 220 °C, based on asphalt viscoelastic performance, SEM image analysis of fiber surface morphology, and fiber molecular structural change via X-ray diffraction technique. Two sets of PAN fiber-reinforced LDPE asphalts were studied: the thermally treated fiber-reinforced LDPE-modified asphalt and untreated fiber-reinforced LDPE-modified binders. Enhanced and exposed fiber surface, in addition to a molecular structural shift toward aromatic form, improves compatibility between the thermally treated PAN fiber and the base asphalt binder. This results in an improved high- and intermediate-temperature performance of the LDPE-modified asphalt binder reinforced with thermally treated fiber, relative to the LDPE-modified asphalt reinforced with untreated fiber.