Field Evaluation of High Reclaimed Asphalt Pavement–Warm-Mix Asphalt Project in Florida

In December 2007, a portion of State Route 11 in Deland, Florida, was milled and repaved with 45% reclaimed asphalt pavement (RAP). These high RAP mixes were produced at lower than normal hot-mix temperatures and with foamed warm-mix asphalt (WMA) technology. This project was the first large production in which the Florida Department of Transportation (DOT) allowed the use of high RAP in combination with WMA. FHWA, in cooperation with Florida DOT and the National Center for Asphalt Technology, was on site for production and placement of the high RAP-WMA. Plant-produced mix was collected by FHWA for performance testing evaluation. Two mixes were produced: a high RAP–hot-mix asphalt (HMA) control mix and a high RAP-WMA mix. Performance tests conducted by FHWA included performance grade (PG) determination of binders, dynamic modulus, and flow number. PG results of the binders indicate that the high RAP-WMA mix is softer than the high RAP-HMA control mix. This is further confirmed by flow number results, where the high RAP-WMA mix had a lower flow number than the high RAP-HMA control mix did. Dynamic modulus results indicate that the high RAP-WMA mix is slightly softer than the high RAP-HMA control mix, especially at intermediate temperatures. Comparison of measured dynamic modulus results with those predicted using the Hirsch and Witczak models confirm that complete blending occurred in the high RAP-HMA control mix. However, incomplete mixing of RAP and virgin binders may have occurred in the high RAP-WMA mix.