Merits of reclaimed asphalt pavement-dominated warm mixed flexible pavement base layers

Use of reclaimed asphalt pavement (RAP) has increased considerably over the past few years; approximately 85% of the RAP available is used within either hot mix asphalt (HMA) or warm mix asphalt (WMA). Within this time frame a number of research efforts have been performed, but most efforts have focused on RAP contents of 50% or less. This paper describes a laboratory effort that studied WMA with RAP contents of 50–100% in the areas of rutting, moisture damage, durability, cracking, and mixing uniformity. Lack of a RAP surplus coupled with performance data presented in this paper indicates that mixtures with more than 50% RAP do not, for most applications, add value to the highway system in present day. WMA with 50% RAP for use as an underlying (or base) pavement layer performed adequately in all performance areas investigated, durability and cracking included.