Effect of Thermal and Oxidative Aging on Asphalt Binders Rheology and Chemical Composition

Aging of asphalt binders is one of the main causes of its hardening, which negatively affects the cracking and fatigue resistance of asphalt binders. Understanding asphalt aging is crucial to improve the durability of asphalt pavements. In this regard, this study aims at understanding and differentiating the effect of temperature and oxygen uptake on the aging mechanisms of unmodified asphalt binders. For that, four laboratory aging procedures were employed. The two standardized procedures, rolling thin-film oven test (RTFOT) and pressure aging vessel (PAV), were considered to simulate the short-term and long-term aging of the asphalt binders, respectively. In addition, two thin-film aging test procedures, the nitrogen atmosphere oven aging test (NAAT) and ambient atmosphere oven aging test (OAAT) were employed to assess the effect of thermal and oxidative aging on unmodified asphalt binder properties. The NAAT procedure is based on the principle that the inert gas minimizes the oxidative aging. The rheological and chemical characterization showed that the high temperatures considered during the NAAT procedure did not change the properties of the unmodified asphalt binders. Therefore, it can be hypothesized that no significant thermal and oxidative aging was observed during NAAT aging procedure for the considered binders and that oxidative aging is the main cause for the hardening.