Implementing fractional viscoelastic model to evaluate low temperature characteristics of crumb rubber and gilsonite modified asphalt binders

In this paper, utilizing the bending Beam rheometer (BBR) test, low temperature rheological properties of asphalt binders which are modified by crumb rubber and gilsonite are investigated. For this purpose, the BBR test was performed on asphalt binder samples containing different extent of modifiers at five temperatures: −6, −12, −18, −24 and −30 °C. In order to interpret results of the BBR test, the general power law is implemented to describe the relation of creep compliance and time which is the main result of the BBR test. It is shown that using the general power law leads to a simple fractional model which could be an appropriate alternative in comparison with the other conventional models such as the Burgers model or the generalized Maxwell model. Besides using the SuperPAVE Performance Grading (PG) protocol, parameters of the simple fractional model are used to evaluate the performance of asphalt binders at low service temperatures.