Effect of Binder Chemistry and Related Properties on the Low-Temperature Performance Parameters of Asphalt Binders

The current Superpave (TM) performance grading specifications were developed under the Strategic Highway Research Program during the 1990s. Since the implementation of these specifications, the petroleum industry, and in turn asphalt binder formulation and production processes, have changed to a great extent owing to various factors, including improving yields and margins. Therefore, there is a need to evaluate and characterize evolving asphalt binder technologies through chemical-, rheological-, and performance-based approaches and to understand the relationships between these various aspects. This paper provides a robust method to characterize the effects of the binder crude source, compositional chemistry, crude oil processing, and modification type, as well as the thermal properties, on the low-temperature performance parameters (e.g., glass transition, crystallization properties, Delta T-c, asphalt binder cracking device [ABCD] T-cr, etc.). As a part of the National Cooperative Highway Research Program 9-60 effort, this work was aimed at providing a robust binder guideline tool for asphalt and additive suppliers, and the asphalt community in general. The experimental matrix includes 50 binders carefully selected based on input from road authorities, researchers, past experience from the field, crude source variability, type of chemical processing involved, modifier type, and so forth. Characterization efforts included tests such those using a bending beam rheometer, an ABCD, the SAR-AD tool composition, and differential scanning calorimetry for asphalt binders at various aging conditions. The outcome of this research sheds new light on binder formulation and manufacturing, especially that related to low-temperature pavement performance.