| AVS 65th International Symposium & Exhibition | |
| Nanometer-scale Science and Technology Division | Monday Sessions |
| Session NS+2D+AS+PC-MoA |
| Session: | SPM - New Imaging and Spectroscopy Methodologies |
| 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 |
The diverse microstructures observed by atomic force microscopy (AFM) in asphalt binder – a complex polymer – suggest complicated intermolecular associations. These microstructures contribute to binders’ bulk mechanical properties; therefore, it is essential to understand chemical-microstructural-mechanical relationships for optimal design of binder-related applications, which range from roads to roofs. The US market for asphalt binders in 2019 is predicted to reach 148 million barrels. [1]
Binders annealed at room temperature for over two months showed time-dependent microstructures, which correlate well with room-temperature steric hardening behavior as verified by other researchers using modulated differential scanning calorimetry. Microstructures of the binder films stabilized after different annealing durations, depending on the dimensions of the molecular structures and the complexity of the molecular interactions among the multiple phases in each bitumen. Distinctive microstructures were observed for remixed binders with increasing asphaltene concentrations. Consistency between our observations [2] and other literature suggests that microstructures observed by AFM are probably not just a surface phenomenon.
Furthermore, the complex nature of binder and the various influencing factors often lead to practical challenges in investigation of its microstructures and their chemical origins. Some of the main concerns related to AFM characterization of binders’ microstructures, namely the dependence of the microstructures on such factors as sample preparation methods, annealing conditions and durations, and chemical composition, were also addressed in this study.
The above findings provide practical knowledge and deeper insights into the establishment of the complicated chemical-mechanical relationships for asphalt binders that pave the way toward tuned binder performance.
[1] https://www.reportlinker.com/p0158665/US-Asphalt-Industry.html
[2] “Time- and composition-dependent evolution of distinctive microstructures in bitumen.” X. Yu, S. Granados-Focil, M. Tao, and N.A. Burnham, Energy Fuels 32, 67-80 (2018).