Abstract
The main objective of this study is to assess the sensitivity of the predicted performance of recycled asphalt pavement (RAP) mixtures to the assumed binder grade. That is achieved with the Mechanistic–Empirical Pavement Design Guide (MEPDG) software to predict the performance of a specific flexible pavement structure with a RAP-modified hot-mix asphalt surface layer. Different design runs are conducted for which all the pavement properties and conditions are held constant except the properties of the surface layer. Specifically, a near-full factorial experiment is performed in which RAP content and effective binder PG grade are the main variables. Comparison of the predicted performance of the various runs reveals important findings on the extent and manner in which those two properties affect pavement distresses and performance. The influence of the assumed PG binder grade on the RAP mixtures, particularly the high-temperature grade, has a significant effect on the predicted amount of thermal cracking and rutting for the given structure. The predicted performance is especially sensitive to changes in assumed PG grade in the range in which the true effective PG grade is expected to fall; the difference from one PG grade to another can be the difference between a well-performing mixture and one that requires redesign. Results emphasize the importance of determining the effective binder grade of RAP mixtures. An added benefit of conducting the numerous MEPDG software runs is the identification of issues that need to be considered when incorporating RAP mixtures in pavement design using the software.
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