Effect of Oxidative Aging on Dynamic Modulus of Hot-Mix Asphalt Mixtures

The dynamic modulus ($|E^{*}|$) of asphalt mixtures is an important parameter in pavement design and analysis. Although the $|E^{*}|$ values of freshly prepared hot-mix asphalt (HMA) mixtures can be conveniently determined through laboratory tests, the $|E^{*}|$ values of field pavements continuously evolve as asphalt binder ages, and hence are difficult to determine. To examine the effects of asphalt binder aging on the $|E^{*}|$ of asphalt mixtures, a new piece of equipment is developed for the accelerated aging treatment of compacted asphalt mixture specimens. A set of small-size sampling, binder extraction, and recovery methods are used to determine the aging state of asphalt binder in asphalt mixtures. Three types of asphalt mixtures with different aging states are used to study the effects of aging on the $|E^{*}|$ changes. In addition, based on the $|E^{*}|$ test results, mixtures’ volumetric properties, and binders’ rheological properties at different aging states, the accuracy and robustness of six commonly used $|E^{*}|$ prediction models are compared. The developed equipment and method are anticipated to assist with the characterization of aged asphalt mixtures and the further improvement of $|E^{*}|$ prediction models.