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Thermal, rheological and failure properties of nine extracted and recovered asphalt cements were investigated to predict cracking susceptibility. Glass transition temperatures, non-isothermal Ozawa crystallization constants and binder fragilities were determined but found to lack a strong correlation with established performance indicators. All binders exhibited thermorheologically simple behavior and master curves for complex modulus and phase angle were readily constructed by applying the time-temperature superposition (TTS) principle. Failure properties of the binders were determined using ductility and double-edge-notched tension (DENT) tests. It was found that the ductility and approximate critical crack tip opening displacement (CTOD) are correlated, although the latter provides more reasonable (lower) values of strain tolerance. The Williams-Landel-Ferry (WLF) equation described the shift factors in dynamic shear, and the WLF constants C1 and C2 correlate reasonably well with ductility and CTOD. It was found that the phase angle was sensitive to asphalt cement quality, with poor performing binders showing a limiting phase angle temperature, T(δ = 45°), nearly 25 °C higher than those of superior performing materials. This investigation demonstrates that recovered binders can be prematurely hardened, likely due to overheating during production or the incorrect use of reclaimed asphalt. As this problem is not recognized when testing material from the asphalt cement supply tank, it is recommended to test extracted and recovered binder from the loose hot mix asphalt. This will assure that the material as placed actually meets performance requirements for the local climate.

This paper documents and discusses performance-based specification properties of 36 asphalt binders. Materials were obtained from commercial sources and purposely distilled from Alberta oil sands crude oils (Athabasca, Cold Lake). Binders were evaluated according to regular Superpave™ specifications, Fraass test, and enhanced protocols based on limiting phase angles and complex moduli. From an overall performance perspective, sol-type binders made from Athabasca and Cold Lake, Alberta and Laguna, Venezuela crudes outperform gel-type ones made from Chinese, Indian, Kuwaiti, Russian, and South Korean sources. Good amounts of asphaltenes together with low wax contents appear to be critical for the production of high quality and durable asphalt binders.

A total of 54 asphalt cements were recovered for pass/fail testing according to various protocols. AASHTO M 320 and proposed Glover-Rowe acceptance specifications appear permissive and lack precision. In contrast, Critical Crack Tip Opening Displacement (CTOD) and limiting phase angle temperature T(δ = 30°) are able to identify satisfactory performing binders with a high degree of repeatability, reproducibility, and sensitivity. Deficits in performance ranged from minor to severe for materials in service for only 4–5 years. A practical specification based on ductile strain tolerance and T(δ = 30°) is anticipated to provide a high degree of protection against premature and excessive thermal and fatigue cracking distress.