Toward the long-term aging influence and novel reaction kinetics models of bitumen

• Published in: The international journal of pavement engineering Vol. 24; no. 2
• Main Authors: Ren, Shisong, Liu, Xueyan, Lin, Peng, Jing, Ruxin, Erkens, Sandra
• Format: Journal Article
• Language: English
• Published: Abingdon Taylor & Francis 28.01.2023; Taylor & Francis LLC
• Subjects: Aging; Asphaltenes; Bitumens; chemo-rheological characterization; consecutive kinetics model; Functional groups; Long-term aging; quantitative conversion relationship; Rate constants; Reaction kinetics; Resins; Rheological properties; SARA fractions
• ISSN: 1029-8436; 1477-268X
• DOI: 10.1080/10298436.2021.2024188

This study aimed to explore the long-term aging influence on chemo-rheological properties and develop novel consecutive models for the long-term aging reaction kinetics of bitumen. The results revealed that the aging index was significantly dependent on the types of selected parameters. The Zero-order model was suitable to describe the long-term aging reaction kinetics of bitumen based on the oxygen-containing functional groups with the reaction rate constants in 0.7-3.3*10 −4 (mol  L −1 ·h −1 ). In the SARA-based consecutive reaction model, the most optimum kinetics model for aromatic fraction was the Third-order reaction model and the corresponding reaction kinetics constant (k 1 ) was 0.02 (mol·L −1 ) −2 (h) −1 . The Zero-order model could well fit the generation kinetics of asphaltene molecules with the reaction rate constant k 2 of 3.85*10 −4 mol·(L·h) −1 . Further, the transformation reaction from the resin to asphaltene molecules was the control step of the whole consecutive reaction model. In this study, when one-unit resin fraction was generated, the consumption amount of aromatic fraction was about 2.82 units. Meanwhile, when one-unit resin fraction was consumed, only 0.58-unit asphaltene could be generated. The developed reaction kinetics models could be beneficial to predict the functional groups distribution and SARA fractions in aged bitumen with different aging degrees.