# Evaluation of Low-Temperature Performance of Recycled
## 1 Introduction
Their findings indicated that the inclusion of RAP generally decreases the J integral value, leading to a reduction in crack resistance, particularly in a mixture subjected to short-term aging. Interestingly, long-term aging did not significantly influence the J integral of the HMA mixture [13]. [PERSON] conducted a semi-circular bending (SCB) test to analyze the effects of the reclaimed asphalt. The experimental results show that the fracture energy of the RAM decreases with the increases in the RAP content and the salt concentration but increases with an increase in the loading rate [14]. Similar to the above research results, some studies have also shown that the LTP of RAMs shows a monotonic decreasing trend with an increase in the RAP content [2; 15; 16]. Some studies have found different trends between LTP and RAP content. [PERSON] et al. used a semi-circular bending test to evaluate the LTP of RAMs through failure load and fracture energy. They observed that, with an increase in the RAP content, both the maximum load and fracture energy initially rise before declining, with the optimal LTP achieved at 30% RAP content [17]. [PERSON] conducted a bending beam rheometer (BBR) test on RAMs, comparing three calculation methods and noting that at a 15% RAP content, the performance is comparable to that of the original asphalt mixture. However, the performance deteriorates significantly when the RAP content exceeds 25% ([PERSON] et al., 2018). [PERSON] et al. used the critical value of bending strain energy density as the primary evaluation index of LTP. Compared with the new material, only the LTP of the mixture with 20% RAP doping is improved, whereas continuing to increase the RAP doping will instead worsen its anti-cracking performance ([PERSON] et al., 2018). Collectively, these studies suggest that the LTP of RAMs peaks at a specific RAP dosage. Subsequently, researchers incorporated RAPs and other materials concurrently into the asphalt mixture to investigate the LTP of mixtures. The interaction of multiple mineral materials led to varying trends in the LTP of mixtures. [PERSON] et al. examined the LTP of RAMs containing RAPs and manufacturing waste roofing asphalt shingles (RAS). They observed that the RAP content below 15% did not significantly affect LTP. However, as the RAP content increased, the LTP deteriorated significantly ([PERSON] et al., 2018). [PERSON] utilized the semi-circular bending (SCB) test to investigate the cracking behavior of asphalt mixtures containing varying percentages of RAP and glass fibers. The results indicated that the incorporation of up to 0.12% glass fiber significantly enhanced the resistance of all mixtures to crack initiation and propagation ([PERSON] et al., 2018). [PERSON] used the indirect tensile (IDT) test and the semi-circular bending (SCB) test to assess the influence of RAPs and taconite minerals on the low-temperature properties of an asphalt mixture. The findings indicated that the addition of RAP resulted in poor low-temperature properties, but when the RAP content was below 20%, the incorporation of taconite minerals could improve LTP. Nevertheless, with a further increase in RAP content, even with higher taconite ore content, the LTP could not be restored ([PERSON] et al., 2018). The above research indicates that when the RAP content is low, the LTP of RAPs remains similar to that of the original mixture in the presence of multiple other materials, and a continuous increase in the RAP content leads to a significant deterioration in LTP. Previous research has investigated the impact of RAPs on their LTP. However, these studies have primarily focused on the effects of thermal-oxidative-aged RAP on the low-temperature properties of the RAMs. The researchers did not categorize RAP according to its different thermal histories, resulting in inconsistencies in the reported maximum dosage of RAP and the observed impacts on the LTP of RAMs. This inconsistency hinders the effective disposal of the RAP and the enhancement of its blending rate.