Mechanistic-Based Evaluation of Performance Thresholds for Engineered Surface Asphalt Mixtures

About the project:

In general, three approaches can be considered to develop performance-based threshold criteria for asphalt mixtures designed using the Balanced Mix Design (BMD) methodology. Approach I is an approach in which a pool of asphalt mixtures representing typically designed and produced mixtures in a given region/climate are subjected to a suite of empirical tests considering different modes of distress. Approach II is an approach in which the empirical test results that are correlated to the results from fundamental tests are used to establish performance criteria. On the basis of these correlations, the empirical test results can be adopted and used as surrogate indices, in lieu of the results from fundamental tests, and then subsequently incorporated into mechanistic empirical (ME) design alongside the volumetric properties of asphalt mixtures.  Approach III is an approach in which the empirical test results are directly correlated to in-service performance of asphalt mixtures to establish performance thresholds.  Although the Virginia Department of Transportation (VDOT) has been extensively building upon its BMD initiative based on Approach I, the empirical tests (for durability, rutting, and cracking) and associated thresholds have never been verified through the use of Approach II. This study provides an opportunity to establish links between the results from empirical and fundamental tests and provide incorporation of the empirical test responses alongside volumetric properties of asphalt mixtures into mechanistic-empirical (ME) structural pavement design. This is a vital step to a practical integration of mixture design and structural design. Moreover, this study provides an opportunity to verify (or refine) the BMD performance thresholds on the basis of ME approach, rather than through the empirical approach alone. Finally, this effort will help establish traffic-based performance thresholds for the empirical tests.  

Project Team

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