Analysis of Asphalt Oxidation by Means of Accelerated Testing and Environmental Conditions

Abstract

The chemical changes that occur to asphalt with oxidation include an increase in oxygen content, as well as the unsaturation of the molecules. This change raises the polarity and stiffness of the material. As a consequence, the elastic response increases, altering its rheology. These transformations are essential to determine pavement performance during its service life. However, the characterization of these chemical and rheological processes cannot be completed because of the inefficiency of current procedures that simulate asphalt oxidation. For this reason, the objective of this study is to characterize asphalt oxidation fundamentally and to relate the observed changes in the materials’ mechanical response. To achieve this goal, a representative group of asphalt samples has been exposed to environmental oxidation, and alternatively to thermal and ultraviolet aging in the laboratory. The samples were characterized chemically and rheologically before the start of the experiment. It was possible to find a correlation between the content of specific chemical species in the material and their mechanical behavior at low and intermediate temperatures. In addition, the present study helps to understand the oxidation phenomena, and helps verify the ineffectiveness of traditional aging techniques, so that they can be modified to simulate the environmental process better.