A Method for Characterizing Reclaimed Asphalt Pavement Degree of Binder Activity

Most transportation agencies in the United States continue to assume reclaimed asphalt pavement (RAP) contributes 100% of its binder to a new asphalt concrete (AC) mixture, which has been proven to be an incorrect assumption, leading to mixtures with insufficient binder and resulting workability and cracking problems. This research assessed the practicality of estimating a realistic reduced amount of RAP binder activity for consideration in AC mixture design, based on indirect tensile (IDT) strength testing of 100% RAP mixtures. The concept and methodology of the Degree of Binder Activity (DoA) was reviewed, modified, and estimated for RAP materials from six states of varying climates in the United States. Pending further validation, the DoA methodology was determined to be practical for inclusion in existing mixture design methods