Diagnostic Techniques for Various Asphalt Refining and Modification Methods

Current asphalt binder production has significantly changed since the Strategic Highway Research Program Superpave days as a result of a number of economic, technical, and environmental reasons. Petroleum sources and product demands have changed considerably, and as a result, refining technologies have had to adapt as well as asphalt suppliers. Blending of crude oils and refining streams as well as additive treatment at various stages of extraction or refining by the addition of additives is now common practice and is continuing to grow. Considering asphalt as a straight-run vacuum residue from a single crude oil is now the exception. Most of the aforementioned changes can enhance binder properties when they are designed and controlled well. However, some of these changes trigger concerns about the quality and consistency of the delivered asphalt binder, especially as current specifications appear insufficient to ensure satisfactory field performance of the end products. The Asphalt Industry Research Consortium (AIRC) was launched by the Western Research Institute in 2015 to help industrial partners evolve with the changing asphalt binder landscape. This study provides select insights produced from the eight partners who helped launch the AIRC program to perform chemomechanical characterization of 52 asphalt binders from around the world. In this study, multiple techniques were instrumental to diagnose various refining processes, compositions, and binder modifiers. These techniques include rheology-Black space analysis, saturates, aromatics, resins- asphaltene Determinator (SAR-AD (TM)), Fourier transform infrared spectroscopy, Waxphaltene Determinator (WD), differential scanning calorimetry, and gel permeation chromatography/size-exclusion chromatography. This paper presents the potential of these techniques for diagnosing air-blown, high-asphaltene-content, high-wax-content, visbroken, styrene-butadiene-styrene modified, ethylene-vinyl acetate-modified, and paraffin-modified binders and blends. The authors also believe that well formulated and compatible blends of any of these production or modification methods may perform well in the field. Links are made between chemically based techniques and understanding how these are manifested in the physical/mechanical properties of the materials.