Changes in the nanoscale asphaltene particles and relaxation spectra of asphalt binders during aging and rejuvenation

Asphalt binder is a widely used engineering material. It is essentially a nanomaterial with colloidal particles suspended in an oily medium. As asphalt binder ages, the colloidal particles are subject to fundamental physicochemical changes such as agglomeration, which is translated into dramatic engineering property changes of the asphalt binder. In engineering practices, organic rejuvenators are often added to the aged asphalt binder, with the hope of breaking down the nanoparticles and restoring its original engineering properties. However, how the nanoparticles evolve during the aging and rejuvenation of asphalt binder remains hypothetical. This study revealed the fundamental changes of the colloidal particles in asphalt binder during aging and rejuvenation. Moreover, changes in the morphology of colloidal particles are connected to the relaxation spectrum of the asphalt binder. As a result, practitioners do not have to rely on complicated methods and equipment to observe asphalt binders at the microscopic level. Instead, they can employ commonly used engineering tests with a dynamic shear rheometer (DSR) to decipher what occurs at the nanoscale during asphalt binder aging and rejuvenation. This would greatly assist practitioners in material selection and design.