Polyethylene based on molecular weight design for eco-friendly asphalt

Polyethylene (PE) is widely used as a modifier for asphalt due to its low cost. However, PE increases the high-temperature viscosity of asphalt, leading to higher construction temperatures and harmful emissions. In this study, PE-modified asphalt with good road performance, energy saving and emission reduction was synthesized by adjusting the molecular weight (M-w) of PE. By studying the effect of PE with different M-w on the viscosity of asphalt, the M-w of PE that can reduce the high-temperature viscosity of asphalt was concluded and the target product PE-4 was synthesized. PE reduces the high-temperature viscosity of asphalt when its M-w is less than the critical molecular weight (M-c) for molecular chain entanglement in the molten state. PE-4 successfully reduced the high-temperature viscosity of matrix asphalt. The pavement performance of PE-4 modified asphalt was characterized. The results showed that PE-4 reduced the penetration of asphalt, and improved its softening point, ductility, and rutting resistance. PE-4 modified asphalt is an eco-friendly asphalt with good road performance. The above data proved that PE with M-w less than M-c makes PE a promising asphalt modifier, which is beneficial to the green utilization of PE.