Investigation on the Effect of Cooling Medium and Aging Condition on Low- Temperature Properties of Asphalt Binder based on BBR Di Wang 1 , Augusto Cannone Falchetto 2* , Chiara Riccardi 3 , Michael P. Wistuba 4 , Lily Poulikakos 5 and Bernhard Hofko 6 ( 1,2,3,4 Department of Civil Engineering – ISBS, Technische Universität Braunschweig, Braunschweig, 38106, Germany, 1. di.wang@tu-bs.de; 2. a.cannone-falchetto@tu-bs.de*; 3. chiara.riccardi@tu-bs.de; 4. m.wistuba@tu-bs.de) ( 5 Empa, Dübendorf, 8600, Switzerland, lily.poulikakos@empa.ch) ( 6 Institute of Transportation, Vienna University of Technology, Vienna, 1040, Austria, bernhard.hofko@tuwien.ac.at) ABSTRACT The low-temperature properties of asphalt binder are fundamental for designing asphalt mixture in the cold regions. This is especially true for new technologies such as Warm Mix Asphalt (WMA), for which a reduction in the production temperature may potentially lead to substantial benefits in terms long-term aging. Currently, the specification addressing the low-temperature property of asphalt binder is based on creep tests performed with the Bending Beam Rheometer (BBR) in ethanol. Recently, an alternative experimental method was proposed to conduct the tests in air. In this paper, the effect of cooling medium and aging temperatures on the rheological properties obtained from BBR tests is experimentally investigated and modeled. First, BBR tests are performed in both ethanol and air on four PAV long-term aged asphalt binders, which were previously RTFOT short-term aged at three different temperatures (123 ºC, 143 ºC, and 163 ºC). Then, the creep stiffness, S(t), and m-value are computed. Finally, the Huet model is used to compare the effect of cooling medium and aging temperatures on the rheological model parameters. Results indicate that the reduced production temperature of 40ºC significantly affects the material properties at low temperatures, while air leads to higher creep stiffness and poorer relaxation capabilities compared to ethanol. Keywords: Asphalt Binder, Aging Temperatures, Bending Beam Rheometer (BBR), Cooling Medium, Huet Model 1. INTRODUCTION Thermal cracking is one of the dominant distresses for asphalt pavement built in regions experiencing a cold climate such as northern America and northern Europe [1,2]. Hence, the low temperature properties of asphalt binder are fundamental for selecting and designing asphalt mixtures. The Performance Grade (PG) specifications were developed by Strategic Highway Research Program (SHRP) during the in 1990’s, in order to characterize asphalt binder over the entire service temperature range [3,4]. The Dynamic Shear Rheometer (DSR) [5,6] is used to obtain the high PG at high and intermediate temperatures, while Bending Beam Rheometer (BBR) [7] is selected to determine the low PG at low temperatures [1]. The current BBR procedure consists of simple low temperature creep tests on small asphalt binder beams immersed in an ethanol bath. However, there is still some ongoing scientific debates on this method with respect to the cooling medium used for conditioning. Ethanol can