Accelerated Pavement Testing of Re-Recycled Cold Central Plant Recycled Asphalt Mixtures

Abstract

Cold central plant recycled asphalt mixtures (CCPR) have been shown to provide a high-quality, economical, and environmentally conscious asphalt base mixture. Existing literature, however, does not indicate what would be an appropriate future rehabilitation method for a pavement that includes CCPR. Given the previously cited benefits of CCPR, it is logical to ask whether a CCPR can be re-recycled and, if so, how will it perform? This paper presents a study of a test section containing a re-recycled CCPR placed at the National Center for Asphalt Technology Test Track. CCPR from a Virginia Department of Transport study on the Test Track was recovered, re-recycled, and placed at 5-in. thick with a 2-in. asphalt concrete (AC) overlay. In preparing for a re-recycled CCPR layer, milling an existing CCPR layer resulted in a coarser gradation and lower indirect tensile strength values. Initially, the re-recycled CCPR test section did not perform well owing to moisture in the aggregate base present during construction of the re-recycled CCPR layer. It is suspected that this moisture negatively affected the curing of the re-recycled CCPR layer. Thus, the re-recycled CCPR layer was milled and re-recycled again (3rd generation re-recycled CCPR) and placed at 5-in. thick with a 2-in. AC overlay. The 3rd generation re-recycled CCPR performed well through 3 million equivalent single axle loads (ESALs), the same number of ESALs that resulted in fatigue cracking and rutting failures in the initial re-recycled CCPR.