Essential work of fracture approach to fatigue grading of asphalt binders

The main objective of this thesis was to apply failure mechanics principles to the characterization of fatigue cracking of asphalt pavements and to identify the correlations between the pavement performance and the composition of binders. The essential work of fracture (EWF) method developed herein is an energy-based testing approach used for the fracture characterization of ductile materials. Developed for both binders and asphalt mixtures, the method provides fundamental parameters, such as specific essential work of fracture and critical tip opening displacement, as potential candidates for a better fatigue specification. It was shown that binders from different sources and with the same performance grade can have very different levels of fatigue susceptibility depending on their manufacturing method and hence failure properties. Also, the currently used binder loss modulus as developed by the Strategic Highway Research Program does not correlate with the newly proposed fracture mechanics based parameters.; An extensive theological and ductile failure investigation on a large interval of testing conditions was performed for a group of binders that are used in the recently built test sections of Highway 655 in northern Ontario. It was found that the shift factors used in the construction of the master curves of the ductile fracture parameters differ from the shift factors of the rheological master curves. The difference was attributed to the response of the internal structure of the binder at the high strain levels that precede the failure phenomenon.