Long Term Research on Bituminous Coarse Aggregates (0-1707-S)

This project summary report summarizes the research performed in Texas Department of Transportation (TxDOT) Project 0-1707. Three key areas were addressed in this four-year project: review and upgrade of the surface aggregate classification system associated with the wet weather skid accident reduction program (WWARP), development of methods to assess aggregate to ensure better performance as part of the hot mix asphalt composite, and assessment and evaluation of use of the Hamburg wheel-tracking device (HWTD) as a means by which to assess aggregate durability. Researchers investigated test methods, field skid resistance performance, the current aggregate classification system, the aggregate imaging system (AIMS), the Micro-Deval (MD) test, the elastic-viscoplastic-plastic model of pavement performance, and dynamic mechanical analysis (DMA). Researchers developed an improved WWARP classification system based on residual polish value and magnesium sulfate soundness or MD testing. They also determined that AIMS is a superior method by which to characterize aggregate properties that impact the performance of hot mix asphalt (HMA). Also, DMA provides an excellent, rapid, and repeatable assessment of the asphalt mastic and/or the asphalt mastic plus fine aggregate matrix.