Compactability and Bitumen Utilization of 100% Warm-Mixed Reclaimed Asphalt Pavement

Understanding the fundamental behavior of Reclaimed Asphalt Pavement (RAP) is a critical prerequisite to a rational design method for mixtures containing very high RAP contents (50% or more). The need for fundamental understanding is heightened when very high RAP contents are used in conjunction with Warm Mix Asphalt (WMA). A mix design method that couples WMA and RAP is needed, and this paper is advancement toward the goal. Results of testing 150 compacted samples strongly supported a partially reusable viewpoint of RAP bitumen. Test results also indicated between 67 to 87% of the total RAP bitumen was reusable and that more viscous materials had lesser amounts of reusable bitumen. The paper also presents component diagrams of high RAP mixtures. The component diagrams account for the bitumen in RAP as it behaves, which consists of three phases. The work presented in this paper shows that very high RAP WMA is feasible, though multiple advancements are needed prior to widespread use.