Viennese Aging Procedure (VAPro): Adaption for Low-Temperature Testing

As for all organic materials, bitumen ages due to anthropogenic and natural influences. The aging process changes the properties of the material. It becomes stiffer and more brittle. This leads to a deterioration of low-temperature and fatigue performance and limits the life span of road pavements. A distinction is made between short-term aging (STA) during production and long-term aging (LTA) during service-life. For simulating aging in the laboratory on bitumen scale, RTFOT for STA and PAV for LTA are used. On asphalt mix scale, various methods have been developed in the past for either loose material or compacted specimens. Many of these methods use unrealistic boundary conditions concerning temperature and pressure, which do not occur in the field. A lately developed method, Viennese Aging Procedure (VAPro), conditions specimens at close-to-field conditions, i.e. a temperature of + 60 C and a pressure of about 0.5 bar. To accelerate aging, VAPro perfuses specimens with a gas mixture consisting of compressed air and traces of reactive oxygen species (ROS). These ROS, such as ozone (O₃) or nitrogen oxides (NO_X) can be found in the atmosphere as well, just in lower concentration. Due to the current layout of VAPro, only cylindrical specimens could be conditioned up until now. However, for investigating the effects of LTA on the low-temperature performance of asphalt mixtures, prismatic specimens are needed for TSRST and UTST. This paper presents the development of a new VAPro version to obtain prismatic specimens and it shows a first comparison of unaged and long-term VAPro aged specimens tested in TSRST with respective DSR results of the extracted binder. With the VAPro method at hand, asphalt mixture can be optimized regarding not only their short-term performance but also their long-term performance including relevant impacts of aging on the performance.