Investigating influence of hard segment content on rheological behavior of thermosetting PU modified asphalt

• Published in: Construction & building materials Vol. 420; p. 135129
• Main Authors: Ding, Heyang, Gong, Hongren, Cong, Lin, Hou, Yudong, E, Guangxun
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 22.03.2024
• Subjects: Hard segment; Modified asphalt; Rheological behavior; Thermosetting PU; Thermosetting PU; Rheological behavior; Hard segment; Modified asphalt
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2024.135129

Thermosetting polyurethane (PU) modified asphalt (TPUMA) possesses enhanced elasticity, flexibility, and mechanical strength, making it a promising solution for challenges like rutting and cracking. The hard segment content (Ch) is a crucial factor influencing the rheological behavior of TPUMA. The specific impact of Ch has not been investigated in previous literature. The key to predicting rheological behavior lies in establishing the constitutive relationship, which has not received sufficient attention. To address these issues, this study aims to comprehensively investigate the influence of Ch on the rheological behavior, thereby establishing a constitutive relationship for TPUMA. Additionally, it seeks to gain a microscopic understanding of viscoelastic properties. Specifically, rheological tests were employed to assess the impact of Ch on linear viscoelastic range, viscoelastic parameters, master curves, fatigue resistance, and creep mechanics. A 5-element viscoelastic model was used to formulate the constitutive relationship of TPUMA. Microstructural tests were conducted to reveal the mechanism behind the rheological behavior. Results indicated that increasing Ch effectively improved the recoverability, flexibility, and fatigue resistance; especially, higher Ch decreased loss tangent and increased the rutting factor. Moreover, compared with the majority of polymer modified asphalt, it was observed that damping phenomenon in the creep-recovery curve while no peak stress in the fatigue damage curve. Thermosetting PU simultaneously increased the high-temperature complex modulus and decreased the low-temperature complex modulus, this effect was particularly pronounced when increasing Ch. The heavier molecular structure and wider molecular-weight distribution of TPUMA were found closely tied to its improved rheological properties. •Increasing hard segment content enhances the rutting resistance, flexibility, and fatigue durability of modified asphalt.•The correlation between model elements and microstructure is established through a 5-element viscoelastic model (2S2P1D).•Thermosetting PU elevates static modulus and high-temperature viscosity while reducing the glass transition modulus.•Increased hard segment content leads to a heavier molecular structure and a wider molecular-weight distribution in TPUMA.