Review of the Superpave performance grading system and recent developments in the performance-based test methods for asphalt binder characterization

Asphalt binder plays an important role in the overall resistance of an asphalt mixture to pavement distresses. The rheological properties should be fully characterized before it is put into field use. Usually, a grading system is employed to evaluate and select the appropriate asphalt binder. The Superpave performance grading (PG) system made the first attempt to directly relate the measured physical properties of asphalt binders to field performance with due consideration of pavement conditions. Conceptually, this approach represents a significant substantial advancement over the traditional penetration and viscosity grading systems. Novel tests and specifications were devised in the Superpave PG system to address the performance requirements. This paper provides a review of the Superpave PG system with respect to workability, rutting resistance, fatigue cracking resistance, and thermal cracking resistance. Although the Superpave PG system is purported to be superior to the traditional grading systems, some deficiencies have been reported regarding the test methods and corresponding evaluation indicators. The Superpave PG system can be further refined if these deficiencies can be addressed effectively. Therefore, the second objective of this paper is to summarize the recent developments in performance-based test methods for asphalt binder characterization. Potential specification tests can be selected from those performance-based test methods in order to refine the Superpave PG system.