Reclaimed asphalt pavement (RAP) is stiffer than the virgin material due to aging, thus it is expected to have worse cracking resistance. By adding bio-based rejuvenators, RAP binder mechanical performances at low temperatures improve: fracture toughness temperature of RAP decreases after the addition of rejuvenators to a level similar to the virgin binder. Furthermore, work to fracture of RAP binder increases after the addition of rejuvenators. Addition of rejuvenators to RAP binder can restore both mechanical properties and toughness at low temperature. However, despite the rejuvenators' addition, physio-chemical oxidation did not reverse as mechanical changes were not caused by chemical changes at functional groups level. Results confirmed how considering the effect of aging is crucial when studying how rejuvenators affect the RAP binder chemically and mechanically.
Rejuvenator is an oil that can be added during asphalt production to restore Reclaimed Asphalt Pavement (RAP) binder. Ten potential locations for rejuvenator addition in asphalt plant were 16 ranked in terms of pavement performance, plant operation, and environmental safety. A full scale 17 production was performed to compare rejuvenator addition to cold RAP on conveyor belt versus 18 addition to hot RAP in mixer (video https://youtu.be/LYBq93e8BG0). Mixture test results indicated that spraying of rejuvenator onto cold RAP facilitates rejuvenator diffusion in RAP 20 binder resulting in improved asphalt fatigue and crack propagation resistance. Both addition 21 locations generated equal organic carbon emissions from asphalt plant. 22
This paper reports a comprehensive study on application of performance-based design method 11 for design of 100% recycled asphalt wearing course mixture and demonstrates the performance 12 of the optimum composition from mechanical, traffic safety and environmental points of view. 13The mixture was designed by balancing rutting using French rut tester and cracking using semi-14 circular bend test. Five iterations of different grading and binder content combinations of 100% 15 RAP mixture were tested before achieving the same performance as a traditional AC8 mixture. This optimum mixture design was then validated by producing asphalt slabs for testing in Model Mobile Load Simulator (MMLS3). The digital image correlation results of the wheel loading demonstrated that performance-optimized 100% recycled asphalt can sustain 2.5 times more load applications compared to the traditional mixture before cracking. This wearing course recycled asphalt mixture was then tested for skid resistance and particle abrasion due to rolling tires and achieved similar results to the reference mixture. The research allows concluding that the proposed mixture design approach can be successfully applied for designing 100% recycled asphalt mixtures that perform similar or better than traditional wearing course asphalt mixtures in all key domains and are safe to the traffic and the environment.
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