Westrack Forensic Team Consensus Report

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Abstract:

WesTrack was the Federal Highway Administration's (FHWA) test facility in Nevada for developing performance-related specifications for hot-mix asphalt pavement construction. After premature rutting failures of test sections placed at the track in June 1997 raised concerns about Superpave mixture design and construction procedures, the FHWA assembled a forensic team composed of academicians, asphalt industry representatives, and State highway agency engineers to investigate. During the team's probe, its members concluded that the asphalt paving community needed a good guide on the design of Superpave mixtures. Such a guide would supplement existing specifications and supporting literature and would incorporate the experience of engineers across the country, including the WesTrack designers. It would be a useful companion to the National Asphalt Pavement Association's Superpave Construction Guidelines.

This publication, Superpave Mixture Design Guide, was prepared by the forensic team to meet the asphalt community’s need. It includes observations on mixture design compaction level determination, performance-graded binder selection, and aggregate selection, followed by extensive discussion of the mixture design process itself. Laboratory performance tests for assessing mixture resistance to rutting are also summarized.

The contents of the guide are the views of the team and do not necessarily reflect the views of the U.S. Department of Transportation. This version of the guide is not expected to be the final word on Superpave mixture design. Both current research studies and additional field experience are likely to yield refinements in the future.

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