What to Consider When Designing a High RAP Content Mix

The use of reclaimed asphalt pavement (RAP) as an asphalt mix component is underutilized. A primary reason for lower RAP usage is lack of experience and guidance on using higher percentages of RAP. This article suggests that designing higher RAP content mixes requires adjusting some mix design procedures. Asphalt content is no longer based only on the virgin asphalt added, but includes both virgin and RAP asphalt. The author describes a method for determining asphalt content using the ignition oven, determining RAP aggregate specific gravity (RAP Gsb), and handling RAP in the laboratory.