Evaluating Cold Central Plant Recycling in High Traffic Volume Applications: A Full-Scale Test Track Study

Asphalt pavements in the United States often incorporate recycled materials, with some highway agencies allowing up to 25%–30% reclaimed asphalt pavement (RAP) in lower courses. While this improves sustainability, using higher RAP percentages could significantly enhance environmental benefits if performance remains similar. One method of using higher RAP contents is with Cold Central Plant Recycling (CCPR), a technique that blends RAP with emulsified or foamed asphalt and, optionally, an active filler to create a nearly 100% recycled asphalt-stabilized base course material at ambient temperatures. However, its long-term performance under heavy traffic is unknown. To address this uncertainty, Virginia Department of Transportation funded a multi-section CCPR experiment at the National Center for Asphalt Technology Test Track beginning in 2012. The thinnest cross section included 4 in. of conventional asphalt surface layers over 5 in. of CCPR, placed on an aggregate base over subgrade. The test section was instrumented to monitor structural responses and surface performance under accelerated loading by triple-trailer trucks. Regular falling weight deflectometer testing enabled backcalculation of material properties over time. The testing lasted nearly 30 million equivalent single axle loads (MESALs) before any surface cracking was evident and the structure endured 40 MESALs before being taken out of service. This far exceeded expectations for a material not yet tested in high traffic and highlights CCPR’s potential for future use. This paper details the test section’s construction, long-term performance, forensic findings following testing, and serves as an important case study for application of CCPR in high traffic volume conditions.