Evaluation of Fiber-Modified Asphalt Mixtures Using BMD Tests

About the report:

The Virginia Department of Transportation (VDOT) is interested in ways to improve asphalt mixture durability. These improvements can be accomplished through several approaches, including the use of performance-enhancing additives, such as fibers, and the incorporation of performance criteria in mixture design and acceptance. This project evaluated the initial laboratory performance of asphalt mixtures that incorporated aramid fiber additives, along with associated control mixtures not containing fibers, on VDOT pilot projects. The mixtures included traditionally designed mixtures (i.e., Superpave) and those designed to meet VDOT’s balanced mix design (BMD) criteria. The study documented production and construction details. Materials were collected during production to evaluate the mixture properties. The laboratory performance information was used to benchmark the as-constructed mixture performance and assess the potential performance benefits of fiber-modified mixtures.

For most of the mixtures evaluated, the addition of fibers did not improve performance test results compared with test results from the control mixtures because of reductions in production binder content from the design binder content. Mass loss, CT index, and indirect tensile strength appeared most influenced by effective binder content and film thickness. Volumetric and BMD test results indicated that fiber-modified mixtures should be designed and optimized based on performance criteria. Long-term field performance of these mixtures must be evaluated to determine the relative performance of the control and fiber-modified mixtures under field conditions.

It is recommended that fiber-modified mixtures be designed using BMD. In addition, the potential benefits of fiber-modified mixtures in resisting cracking should continue to be evaluated when mixtures are properly designed and produced

_{Disclaimer Statement:The contents of this report reflect the views of the author(s), who is responsible for the facts and the accuracy of the data presented herein. The contents do not necessarily reflect the official views or policies of the Virginia Department of Transportation, the Commonwealth Transportation Board, or the Federal Highway Administration. This report does not constitute a standard, specification, or regulation. Any inclusion of manufacturer names, trade names, or trademarks is for identification purposes only and is not to be considered an endorsement.}

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