| AVS 66th International Symposium & Exhibition | |
| Nanometer-scale Science and Technology Division | Wednesday Sessions |
| Session NS+2D+AS-WeA |
| Session: | Probing and Modifying Surface and Interfacial Chemistry at the Nanoscale |
| Presenter: | Nancy Burnham, Worcester Polytechnic Institute |
| Authors: | x. Yu, Worcester Polytechnic Institute S. Granados-Focil, Clark University M. Tao, Worcester Polytechnic Institute N.A. Burnham, Worcester Polytechnic Institute |
| Correspondent: | Click to Email |
Understanding of how the chemistry of asphalt binders (i.e., bitumens) affects their bulk properties is critical for development of structure-related mechanical models and performance-based specifications for asphalt binders, including mitigation of potholes and improved recycling of this non-renewable material. However, establishing the chemical-mechanical relationships that govern asphalt binders’ properties remains a challenge due to binders’ complex chemical makeup [1] and the intriguing dynamic molecular interactions among binders’ various chemical constituents. [2] Here, we investigate the effect of chemical composition on binders’ microstructure and thermal and rheological behavior. Two virgin binders from different crude oil origins were chosen and a series of derivative binders was made by remixing different weight ratios of the asphaltenes and the maltenes obtained from the two source binders. Thermal and rheological properties of all binders were measured using modulated differential scanning calorimetry and dynamic shear rheometry, respectively. Binders’ microscopic characteristics (e.g., nano- and micro-structures and their contrast in phase images) were evaluated using atomic force microscopy. In bitumens with more miscibility between the asphaltenes and maltenes, the samples appear to undergo a sol-gel transition as the asphaltene concentration increases above 25%. In less miscible bitumens, micro-scale phase segregation is readily apparent at the surface. Our results show that bitumens’ characteristic microstructures, as a result of the complex molecular interactions among their various chemical components, are correlated with their bulk thermal and mechanical properties. Notably, the asphaltene/maltene ratio alone cannot predict a bitumen’s bulk properties. Instead, a bitumen’s distinctive microstructures and its colloidal miscibility index provide meaningful insights into the effect of chemical composition on glass transition, phase stability, and rheological properties of the bitumen, which may in turn help improve the sustainability and design of roads. [3]
1. X. Yu et al., Adv. Colloid Interface Sci. 218, 17-33 (2015).
2. X. Yu et al., Energy & Fuels 32, 67-80 (2018).
3. X. Yu et al., submitted