Evaluation on the chemical cross-linking network and performance of polyurethane-modified asphalt

Polyurethane(PU)-modified asphalt has excellent strength and toughness, while the influenceof PU composition and distribution on asphalt performance remains unclear. Thisresearch incorporates different compositions and dosages PU with asphalt toinvestigate the formation process of the PU cross-linked network. The PU wasextracted from asphalt and compared with synthesized PU to analyze theinteraction between PU and asphalt. The results reveal that the PU cross-link networkstructure enhances the temperature performance of asphalt. The enhancementmechanism primarily hinges on the establishment of a chemically cross-linkednetwork. With higher PU dosage, a more continuous network structure emerged.The PU dispersion transitions from a uniform distribution at the nanoscalelevel to a structure characterized by micron-scale particle aggregates. Theoptimal dosage of PU is 20%. Considering the low-temperature flexibility, thecontent of hard segment should be less than 40%. This research offers avaluable theoretical foundation for improving asphalt performance.