||High-RAP (Recycled Asphalt Pavement)/High-Binder Asphalt Concrete Mixes
Michael M. Sprinkel
Associate Director for Structures
||The use of reclaimed asphalt pavement (RAP) in asphalt mixtures has steadily increased, and state transportation departments are considering the economic and environmental benefits of percentages of RAP above 20-25 percent by volume in their mixes. The main obstacle to increasing RAP amounts is limited knowledge of how the binder in the RAP affects the virgin binder in the mix. High performance grade (PG) of binder in the RAP results from the aging it experiences while in service. |
Recent studies report that adding RAP increases the effective PG of combined RAP and virgin binder by one grade above that of the virgin binder alone. Performance properties of mixtures may be affected, including resistance to cracking and rutting, as well as dynamic modulus. Where increasing RAP content seems to improve rutting resistance, it reduces cracking resistance. This research will build on prior studies to optimize binder and high-volume RAP proportions to achieve desirable mix characteristics.