Low-temperature performance grade characterisation of asphalt binder using the dynamic shear rheometer

Currently, the bending beam rheometer (BBR) test is the standard method for evaluating the low-temperature performance grade (PG) of asphalt binders. Despite its use, there are limitations with the BBR test with respect to the amount of asphalt binder needed for test specimens, the relative difficulty in preparing specimens, and the overall testing efficiency. On the contrary, the dynamic shear rheometer (DSR) is an efficient test method that is widely used to determine the PG at intermediate and high temperatures. In this study, DSR temperature-frequency sweep tests using the 8-mm parallel plate is proposed as an alternative to the BBR. The method takes advantage of the time-temperature superposition principle and linear viscoelastic interconversion to predict the BBR creep stiffness and m-values at 60 s from the modulus and phase angle measured by the DSR at intermediate temperatures. Two conversion methods were used to verify the ability to predict BBR properties using DSR testing based on 45 binders of diverse PG. The DSR-based method yields good agreement with measured BBR data. On average, the continuous low-temperature PG predicted using the DSR method is within 2.7 degrees C of that measured using the BBR.

Automated summary

The dynamic shear rheometer (DSR) can be used as an alternative method to the bending beam rheometer (BBR) test, predicting the performance of BBR using the time-temperature superposition principle and linear viscoelastic interconversion. Compared to BBR, DSR method has higher testing efficiency and lower specimen preparation difficulty.