Compaction and Performance of Warm-Mix Asphalt with High-Reclaimed Asphalt Pavement

Abstract

Incorporation of high contents of reclaimed asphalt pavement (RAP) in asphalt mixes produced at warm-mix asphalt (WMA) temperatures raises questions about the interaction between the RAP and the WMA additives and the performance of these mixes. In this study, a two-phase experimental program was devised to examine the effect of six factors, including mixing/compaction temperatures, RAP content and source, WMA type, binder grade, and conditioning duration, on the volumetric properties, compaction, and cracking performance of RAP-WMA mixes. The results showed that mixing/compaction temperatures, RAP content, and RAP source have statistically significant effects on the compaction of the mixes. Semicircular bend (SCB) results showed that RAP content overwhelms the effect of all other factors. More importantly, the experimental program revealed that some mixes passed the volumetric requirements but failed the cracking test. This is a critical finding given the increased production of unconventional mixes that came into use after the development of current specifications. The current state of practice needs to be upgraded to incorporate performance as part of the mix design process.