Fracture Behavior of Asphalt Emulsion Warm-Mix Recycled Asphalt Mixtures Incorporating High RAP Contents and Rejuvenator

Warm mix recycled asphalt mixture with asphalt emulsion (WMRA-AE) has the potential to achieve high reclaimed asphalt pavement (RAP) content and enhanced pavement performance. However, its high RAP content increases susceptibility to cracking. To address this issue, a rejuvenator was introduced to improve the anticracking performance of WMRA-AE. This study investigated the effect of the rejuvenator on the fracture behavior of WMRA-AE using a semicircular bending (SCB) test combined with digital image correlation technology. Our experiments revealed that the fracture process of WMRA-AE could be effectively divided into three stages using results of crack tip opening displacements and full-field mean horizontal strains. At 25°C, WMRA-AE with 100% RAP (WMRA-AE-100) exhibited the highest fracture toughness and fracture energy but demonstrated inferior performance in other fracture indices. Moreover, at −10°C, WMRA-AE-100 exhibited the lowest fracture resistance. Notably, the fracture performance of WMRA-AE with high RAP contents (70%, 100%) and rejuvenator at −10°C was improved significantly, surpassing that of normal asphalt mixtures. Further, correlation study between SCB fracture parameters and low-temperature bending failure strain revealed that fracture energy and the cracking resistance index were the most reliable indicators for evaluating the low-temperature fracture performance of WMRA-AE. These findings highlight the critical role of rejuvenators in improving fracture resistance of WMRA-AE with high RAP contents, particularly under low-temperature conditions. This study can provide valuable insights into design optimization and application of WMRA-AE with high RAP contents in sustainable pavement engineering.