Study on Durability of Warm Mix–Recycled Asphalt Mixture with Asphalt Emulsion and High RAP Content Considering Aging and Freeze–Thaw Cycle Effects

Warm mix–recycled asphalt mixture with asphalt emulsion (WMRA-AE) has the potential to achieve both high reclaimed asphalt pavement (RAP) content and enhanced pavement performance. However, its long-term durability under aging and freeze–thaw cycling conditions remains insufficiently explored. In this study, three types of WMRA-AE and one conventional asphalt mixture were subjected to laboratory-simulated long-term aging and repeated freeze–thaw cycles, followed by evaluations of both mixture performance and binder properties. Results showed that the WMRA-AE containing 100 % RAP (WMRA-AE-100) exhibited the most severe performance degradation after freeze–thaw cycles, whereas the same mixture modified with a rejuvenator (WMRA-AE-100-R) showed the least deterioration. Pull-off tests demonstrated that the rejuvenator effectively restored the adhesive properties of aged asphalt, thereby improving resistance to freeze–thaw damage. Furthermore, long-term aging enhanced rutting resistance while reducing low-temperature cracking resistance and water stability. Notably, WMRA-AE-100 exhibited superior aging durability, whereas WMRA-AE-100-R showed poorer aging durability. Binder testing revealed that the asphalt in WMRA-AE-100-R underwent the most significant property changes during aging, whereas the binder in WMRA-AE-100 remained the most stable explaining the observed differences in aging behavior between mixtures. Among all tested mixtures, WMRA-AE-75-R (comprising 75 % RAP and a rejuvenator) demonstrated the reliable durability under both long-term aging and freeze–thaw conditions. These findings suggest that WMRA-AE-100 is best suited for regions with minimal freeze–thaw impact, whereas WMRA-AE-75-R is preferable for environments requiring resistance to both thermal aging and freeze–thaw degradation. To expand the applicability of WMRA-AE-100-R across broader climatic regions, further improvement in aging resistance is recommended through optimized rejuvenator formulations or supplementary additive strategies.