Analyzing low-temperature performance of bitumen and mastics with the Dresden cryogenic test using the DSR as a substitute for the BBR test

This paper investigates the use of the Dresden Cryogenic Stress Test (DCST), performed with the Dynamic Shear Rheometer (DSR) as an alternative method for characterizing the low-temperature behavior of bitumen and mastics. The DCST is based on the principle of the thermal stress-restricted specimen test (TSRST) for asphalt mixtures. The primary objective is to evaluate the effectiveness of the DCST as an alternative to the traditional Bending Beam Rheometer (BBR) test. The secondary objective is to analyze and discuss the influence of the filler content on the low-temperature performance of the materials tested. The testing was done simultaneously at two universities, TU Dresden and RWTH Aachen, on the same materials, one bitumen and two mastics in the ratio of 1:1.2 and 1:1.4 respectively. The materials were short-term and long-term aged. To evaluate the effect of aging and filler content, two indexes were defined and calculated: aging index (AI) and filler content index (FCI) for BBR and DCST. The DCST results showed good repeatability between the two universities. The ranking of the materials between the BBR test and DCST in terms of AI and FCI was found to be similar and attributed to the stiffness of the materials. The DCST offers the benefits of high repeatability and reproducibility. Moreover, it is applicable for testing bitumen as well as mastics and could be better related to asphalt mixture performance. • The novel cryogenic test using a DSR effectively replicates the BBR test for low- temperature bitumen assessment. • Testing at two labs confirmed its consistent accuracy and applicability for both neat binders and mastics. • Strong correlation with BBR-based aging and filler content rankings was observed. • DCST more realistically simulates actual cryogenic thermal stress conditions at the binder scale. • This test enables a multi-scale perspective linking binder-level results to asphalt mixture performance.