Toward the long-term aging influence and novel reaction kinetics models of bitumen
Shisong Ren, Xueyan Liu, Peng Lin, Ruxin Jing, Sandra Erkens
Abstract
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 oxygencontaining functional groups with the reaction rate constants in 0.7-3.3*10 - (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 (molL -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(Lh) -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.