Effects of short-term aging on the physical and rheological properties of plastic waste-modified bitumen

The current study aimed at examining the potential use of recycled low-density polyethylene (LDPE) plastic waste as a modifier for bituminous binders. Plastic bags were collected, cleaned, shredded and were characterized by using Fourier transform infrared spectroscopy analysis, thermogravimetry, and differential scanning calorimetry (TGA-DSC) test. The LDPE plastic waste was blended with 35/50 penetration grade bitumen at three concentrations (1%, 3%, and 5% by weight of bitumen). The physical properties of the modified bitumen were determined using softening point and penetration test, while the rheological properties were evaluated using a dynamic shear rheometer test. The tests were conducted on the unaged binders and on the rolling thin film oven test residue. The test results showed that when plastic waste had been added into bitumen, the penetration values decreased, whereas the softening point increased. Furthermore, the rheological properties were improved at high in-service temperatures leading to a decrease in thermal and kinetic sensitivities and an increase in the rutting resistance of bitumen. The modified bitumen with 3% of plastic waste was the most consistent and least sensitive to aging. In addition to improving the properties of bitumen binders, industrial waste use practices will also protect the environment.