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A high-performance thin asphalt overlay (HPThinOL) is specified as having a thickness of 1 in. or less and is used in applications requiring high levels of rutting and fatigue resistance. HPThinOLs are used as a pavement preservation strategy and are placed on pavements that have remaining structural capacity that is expected to outlive that strategy. Current specifications for HPThinOLs generally call for a polymer-modified asphalt (PMA). However, PMA binders are more expensive than unmodified asphalt binders. This expense, coupled with the higher binder content requirement generally associated with HPThinOL, could lead to an initial higher cost in relation to other pavement preservation strategies. Although the higher initial cost can be offset by incorporating high amounts of reclaimed asphalt pavement (RAP), the use of high amounts of RAP in PMA mixtures might adversely affect the mixture performance (stiffness, cracking, or workability). Warm-mix asphalt (WMA) technology may improve the workability of HPThinOL that incorporates high RAP content and PMA binders. This study evaluated the effect of PMA binders, high RAP content, and WMA technology on the stiffness, resistance to reflective cracking, moisture susceptibility, and workability of HPThinOL mixtures. PMA binders and high RAP content increased the stiffness of HPThinOL significantly; however, the use of WMA technology lowered mixture stiffness and improved workability. PMA may improve the cracking resistance, moisture susceptibility, and rutting resistance of high-RAP HPThinOL mixtures, depending on whether a WMA technology is used.

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Softer binders have been used to compensate for the stiffness of reclaimed asphalt pavement (RAP) binders in mixtures; however, several studies have shown that asphalt rejuvenators can allow more RAP to be incorporated in mixtures than can softer binders alone. Nevertheless, rejuvenators are not specified by some state agencies because of potential rutting-related concerns. Therefore, the use of polymer modified asphalt (PMA) binder was evaluated to ascertain if it can remedy any rutting performance degradation while maintaining or improving the cracking characteristics of the mixtures. The objective was to produce mixtures with high RAP content that perform similar to or better than an all-virgin-material control mixture. The effect of five asphalt rejuvenators on the performance of a 50% RAP surface-layer mixture was evaluated relative to rutting and cracking. The results illustrated that the rejuvenators degraded the rutting resistance of the 50% RAP mixture, although the use of PMA binders remedied these degradations. The rejuvenators improved the fatigue cracking resistance of the 50% RAP mixture to a level higher than did the all-virgin control mixture and also the 50% RAP mixture with softer binder alone. Overall, the data indicated that a combination of an asphalt rejuvenator and a PMA binder was required to yield a high RAP mixture with similar or better performance than a similar conventional mixture.