Using the DSR to determine cold temperature properties and thermal cracking as an alternative to BBR

Abstract: The Superpave specifications currently rely on the Bending Beam Rheometer (BBR) to determine the low-temperature performance grade of asphalt binders. Originally adapted from the plastics industry during the Strategic Highway Research Program (SHRP), BBR testing requires additional aging in the pressure aging vessel (PAV) beyond what is necessary for dynamic shear rheometer (DSR) testing. Advances in DSR technology, however, now allow for effective characterization of low-temperature properties in asphalt binders, suggesting a potential alternative to BBR for cold-temperature grading and assessment.
This study analyzed over 100 asphalt binders to explore correlations between BBR and DSR data through master curve analysis, ultimately developing a simplified DSR-based procedure. This paper presents data comparisons to evaluate the DSR method as a viable surrogate for AASHTO T313, including ΔTc (delta Tc) calculations, using both a comprehensive dataset and a secondary dataset tested with the abbreviated method. This approach simplifies Superpave implementation by eliminating the need for the BBR, a valuable advantage in regions with limited testing resources. In the United States, this method also provides formulators and Departments of Transportation with a faster, more economical testing alternative, reducing both time and costs.
Additionally, as transportation agencies increase the use of reclaimed asphalt pavement (RAP) to address cost and environmental concerns, this abbreviated DSR-based method offers an efficient way to assess the low-temperature properties of the aged binder in RAP, because the amount of extracted and recovered binder needed for testing will be significantly reduced.