New Methodology to Find the Healing and Fracture Properties of Asphalt Mixes Using Overlay Tester
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Asphalt layers under different repeated loading and rest periods experience both fatigue and healing processes. The tests are costly and time consuming and the results are highly variable. Current methods of evaluating these phenomena using the overlay tester (OT) rely on counting the number of load repetitions until the crack breaks through the sample. This research provides a novel analysis method based on viscoelastic fracture mechanics and finite-element modeling to predict the actual crack growth rate in asphalt mixes, both in laboratory compacted and field samples, by using the OT. Furthermore, the new method uses the principles of viscoelastic fracture mechanics to find the fracture and healing properties of the asphalt mixes. The resulting test is fast, less costly, and more repeatable than previous methods using the OT. The precision of the test method was determined and improved by testing lab compacted specimens. The coefficients of variation of the undamaged properties of the laboratory compacted mixture are comparable with the test results. 2013 American Society of Civil Engineers.