Review of Lab-Accelerated Aging Techniques of Asphalt Mixes

Bitumen aging contributes to main pavement distress due to the changes in rheological, chemical, and physical characteristics of bitumen. Mainly, aging process can be divided into two categories, the first category namely short-term aging takes place during the heating up of bitumen and aggregate, mixing, transportation, laying down, and compaction. While the second category of aging takes place during the service life of pavement which is denoted as long-term aging. Consequently, researchers’ focus is to simulate bitumen aging in the lab by developing lab-accelerated methods to simulate the process of bitumen aging and studying the rate of change before and after aging. This article reviews these methods and compares the extent of the impact on lab-aged bitumen with old bitumen. The main outcome is, that the duration of exposure to high temperatures, which is the dominant method to accelerate aging process, resulted in inadequate changes in the structure of the bitumen molecule, hence, making it different from old bitumen. For that reason, using oxidants such as hydrogen peroxide showed more reliable results but requires more attention by researchers to achieve a standardized aging process of bitumen.