Viennese Aging Procedure – Behavior of Various Bitumen Provenances
Bitumen changes its properties in the course of time under natural and anthropogenic influences due to its organic origin. These processes are commonly called “aging”. The material becomes stiffer and more brittle, resulting in less favorable low temperature and fatigue behavior. For this reason, it is important to simulate the aging of the material in the laboratory in an accelerated way to study the change in material behavior and minimize damage on the road. On the bitumen level, the standardized methods RTFOT (Rolling Thin Film Oven Test) and PAV (Pressure Aging Vessel) are used. Various methods have been developed in the past to simulate aging of asphalt mixes or compacted specimens. The study presented in this paper evaluated the aging method “Viennese Aging Procedure” (VAPro) for applicability with the aid of a parameter study with bitumen of different origin. VAPro uses realistic boundary conditions (temperature: +60 °C, pressure: ~0.3 bar) and increases the rate of aging of the compacted asphalt mix specimen by perfusing (1.0 l/min) with ozone and nitric oxides enriched air for three days. The state of aging of the extracted bitumen is assessed using the Dynamic Shear Rheometer (DSR). Significant differences between the employed bitumen are determined, which is probably caused by their different initial stiffness and their origin. The stiffness after VAPro of the extracted bitumen is between 1.2 and 2.6 times the RTFOT+PAV-aged state.
KeywordsVAPro Ozone NOx Long term aging Hot mix asphalt Stiffness DSR
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