Asphalt pavements are 100% recyclable. For more than 30 years, agencies have allowed the use of RAP in new pavement construction with great success.
The National Cooperative Highway Research Program (NCHRP) and the National Center for Asphalt Technology (NCAT) have conducted several research projects on the use of RAP in new pavement construction (NCHRP 9-12, NCAT 96-05, & NCAT 95-01).
The main concern with the use of RAP is with the effect of the RAP binder on the virgin binder. As a result with the NCHRP report, the Federal Highway Administration (FHWA) has developed guidelines for incorporating RAP in new pavement construction. The guidelines recommend changes to the virgin binder grade based on the percentage of RAP incorporated.
Caltrans has allowed the use of a maximum of 15% on QC/QA projects. In Fall of 2006, Caltrans issued a Caltrans Policy Directive (CPD) that allows HMA producers to use a maximum of 15% rap on ALL Caltrans projects. As a result, local agencies will soon follow suit.
Local agencies in southern California have used RAP since the early 70's. The predominant specification book for local agencies in southern California, the Greenbook, allows the use of RAP in HMA.
Other Resources:
A one page information sheet on RAP:
Click HERE to download a presentation on RAP by CalAPA member Tom Carter delivered at the CalAPA "California Asphalt Pavement Forum."
