Recent Advances in Field Evaluation of RAP in the United States

Over the past two decades, recycled asphalt pavements (RAP) have increasingly been used in both new pavement construction and rehabilitation projects. Use of high percentage of RAP in pavements may increase potential of cracking and moisture damage in in-service asphalt layers. To better understand the in-situ changes in RAP-containing asphalt, there is a need in fast yet reliable field methods for evaluating hardening effects and moisture damage. This article provides historical perspective on laboratory testing methods for RAP and summarizes most recent advances in field evaluation of RAP with use of portable spectroscopic equipment during the recently completed SHRP 2 R06B study on field applications of spectroscopy. The results of this study indicate that in the near future, the in-situ measurements of oxidative hardening and moisture content by portable infrared devices can be incorporated into pavement management systems.