Interrelationships in Rheology for Asphalt Binder Specifications

The formation of the Strategic Highway Research Program (SHRP) test parameters implemented in Superpave were based upon linear visco-elastic measurements, for example G*/sind, G*.sind, S(t), and m(t). In addition, the SHRP research defined parameters associated with the Christensen-Anderson model, defining R-value and cross-over frequency. More recently, other test parameters have been proposed for use such as the Multiple Stress Creep Recovery (MSCR) test (Jnr), Glover-Rowe parameter (G*.cosd2/sind), the difference between Tcrit from S(t) and m(t), ( Tc), visco-elastic transition temperature (Tvet) and others. Some of the proposed test parameters relate directly to a linear visco-elastic understanding of the binder whereas other parameters can best be described as non-linear parameters. Both non-linear and linear parameters are important for pavement performance and in many cases these are interrelated through an understanding of time and temperature susceptibility of the asphalt binders. This paper demonstrates how the model parameters can be interrelated through an understanding of the visco-elastic properties and how a simple understanding of a few key asphalt binder parameters can be used to estimate other parameters. Limitations of this approach, especially in the non-linear region will also be discussed.