Fatigue Cracking of Asphalt Pavements
by Andrew Braham, PH.D., P.E., Associate Professor, University of Arkansas and
Shane Underwood, Ph.D., Assistant Professor, Arizona State University
Recorded October-November 2016
During its 91st Annual Meeting in 2016, the Association of Asphalt Paving Technologists (AAPT) held a successful Leading Edge Workshop on fatigue cracking performance methods for asphalt mixtures. AAPT is looking to build off of this workshop by partnering with the Asphalt Institute to host a three-part webinar series that will provide a foundational understanding of the techniques that have been developed for quantifying fatigue cracking and a comprehensive review of the laboratory and evaluation methods for capturing and describing fatigue cracking. Techniques covered will include energy-inspired, continuum damage, fracture, and healing methods. Tests will include bulk material testing and notch-based testing.
Session Part I: Introduction
Part I of the webinar series will cover baseline information, including the context and influence of cracking, and the increased relevancy of cracking on asphalt pavements. Next, an overview of basic theories on crack process, damage growth, and macrocracking will be discussed. In addition, information regarding the general approaches of fracture mechanics, energy methods, continuum damage methods, and healing will be provided. This will involve a broad discussion on general issues that need to be faced in each area. Part I will finish with brief information on the topics to be covered in Part II of the series.
Session Part II: Fatigue Cracking Tests for Asphalt Materials
The second part of the webinar series will provide information on asphalt binder and mixture fatigue cracking tests. For asphalt binders, the repeated loading, double edge notched, and binder fracture energy tests will be reviewed. For asphalt mixtures, the presentation will be subdivided into two sections. The first subsection of asphalt mixture tests will discuss those tests that do not incorporate a notch – including the four-point beam, cylindrical geometry, indirect tension, trapezoidal, overlay, dogbone, and loaded wheel tests. The second subsection of asphalt mixture tests will discuss those tests that do incorporate a notch – including the Semi-Circular Bend, Disk-Shaped Compact Tension, Single-Edge Notch Beam, and the Double Edge Notch Prism tests. Part II will finish with brief information on the topics to be covered in Part III of the series.
Session Part III: Analysis and Interpretation of Fatigue Cracking Test Data
Part III of the webinar series will present an overview of the three broad categories of fatigue analysis: Energy-Inspired, Continuum Damage, and Fracture techniques as well as details of prevalent analysis methods within these categories. Where possible, comparisons between the techniques, both in technical approach and application will be provided. The series will conclude with a summary of the state of fatigue cracking research and ideas for moving forward.