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Rejuvenating the reclaimed asphalt pavement by crumb rubber modified binder for recycling in new pavements arouses a great interest as a sustainable paving technology that uses waste to recycle waste and hinders resource depletion. By investigating rheological and adhesion/cohesion characteristics of the asphalt binder, this study aims to divine optimal dosages of reclaimed asphalt and crumb rubber that enhance the overall performance of the binder without undermining any feature. Thirty binders produced from two types of virgin binder, two sources of reclaimed asphalt, three dosages of reclaimed asphalt, and two dosages of crumb rubber were prepared and tested. Bonding, rheological, and physiochemical characteristics of binders were investigated using pull-off test, dynamic shear rheometer, and Fourier transformed infrared spectroscopy. The results show that mixing reclaimed asphalt with rubberized asphalt greatly enhances the cohesion strength, rutting resistance, creep resistance, and colloid homogeneity. However, certain reclaimed asphalt and crumb rubber dosages undermine the fatigue cracking resistance. The physiochemical investigation revealed that the crumb rubber chains intensively swell and disintegrate simultaneously during mixing with virgin binder and further mixing with reclaimed asphalt. Through correlation analysis, it was emphasized that the improvement of cohesion strength and rheological characteristics is ascribed to the physiochemical changes caused by crumb rubber interaction and reclaimed asphalt addition. [Display omitted] [ABSTRACT FROM AUTHOR]

Incorporating reclaimed asphalt pavement (RAP) increases concern about long-term fatigue and cracking resistance of the resultant mixture due to the presence of an aged binder. Using a rejuvenator is one of the most promising methods to prolong the aging time for initial cracking and allow the inclusion of higher RAP content. Many discrepancies exist in the literature about rejuvenators' effectiveness in improving the fatigue performance of RAP binder and mixture. These ambiguous and contradictory findings are attributed to using different rejuvenator types and dosages, RAP sources and percentages, binders and mixture fatigue testing approaches. This paper comprehensively reviews and investigates the existing literature to fully understand the rejuvenation mechanism and its impact on the fatigue and cracking resistance of RAP binder and mixture using the most available tests and indicators. In addition, a rigorous laboratory study is carried out to determine the sensitivity of indicators to mix composition and variability. It is concluded that the inclusion of rejuvenators into RAP binders and mixtures may not improve their fatigue and cracking performance to the same level as virgin materials. But by utilizing polymer modification, the bonding between materials increases significantly, which results in better fatigue performance of rejuvenated RAP materials. Despite the positive impact of rejuvenators on RAP mixture fatigue performance, a comparison of different tests results does not offer a consistent indicator for determining fatigue resistance. Hence, it is recommended that the future research should be carried out with reasonable test methods, more complicated analytical techniques, service life characterization models, and climate identical test conditions, to clarify the durability index. Also, a complete evaluation of field performance utilizing RAP and rejuvenator is valuable. [ABSTRACT FROM AUTHOR]