## 3 Results and Discussion
### Thermal Cracking Property (Low Temperature)  
The stiffness and m-value characteristics of different asphalt binder formulations were evaluated at a temperature of \(-12~{}^{\circ}\)C using the BBR. Understanding the performance of asphalt binders in cold areas is crucial due to the potential for thermal cracking and its impact on pavement durability. Figure 6 shows the virgin binder (PG 64-22) as the reference point, with a rigidity of around 185 MPa. When 10% Trinidad Lake Asphalt (TLA) is added, the stiffness reduces significantly to approximately 179 MPa, suggesting a reduction in rigidity and a possibility of increased brittleness at low temperatures. However, when the  
Figure 5: G*sin\(\delta\) at 25 \({}^{\circ}\)C of the modified binders at RTFO + PAV aged conditions. The introduction of CRM exhibits a distinct pattern. When 5% CRM is added to the virgin binder, the stiffness increases to around 151 MPa. This indicates that the stiffness is higher than that of the virgin binder but lower than that of TLA-modified binders. When a 5% concentration of CRM is mixed with a 10% concentration of TLA, the stiffness value increased to approximately 195 MPa, suggesting that CRM had only a minor effect on increasing rigidity. By increasing the TLA content to 20% and adding 5% CRM, the stiffness increased to around 238 MPa. However, this value is still lower than using TLA alone, but higher than the combination with 10% TLA. Increasing the concentration of CRM by 10% further decreases stiffness. For example, a binder containing 10% CRM demonstrates a stiffness of approximately 141 MPa, which is similar to the rigidity of the original binder. The combination of 10% CRM and 10% TLA yields a stiffness of around 148 MPa, indicating a substantial decrease in rigidity when compared to binders treated only with TLA. When 20% TLA is combined with 10% CRM, the resulting stiffness is roughly 150 MPa. This suggests that as the CRM content increases, the stiffness decreases, although it is still higher than when CRM is used alone. The scientific justification for these observations is based on the characteristics of TLA and CRM. The presence of TLA, characterized by its compact molecular arrangement and elevated asphaltene concentration, greatly enhances the rigidity of the binder, rendering it more inflexible and possibly prone to brittleness under cold conditions. In contrast, CRM improves the elasticity and flexibility of the binder, thus offsetting the heightened rigidity generated by TLA. Striking the right balance between TLA and CRM is essential for maximizing the efficiency of asphalt binders, particularly in frigid regions where the risk of becoming brittle is a significant issue. Analyzing the m-value characteristics of different asphalt binder blends at a temperature of \(-\)12 \({}^{\circ}\)C, as depicted in Figure 7, offers an additional understanding of the stress relaxation qualities of asphalt binders under low-temperature conditions. Higher values  
Figure 6: Stiffness at \(-\)12 \({}^{\circ}\)C of the modified asphalt binders after RTFO + PAV aged condition. of m often indicate greater resistance to thermal cracking. The virgin binder exhibits an m-value that slightly exceeds the minimum threshold, indicating its commendable performance at low temperatures. When 10% TLA is introduced into PG 64-22, the m-value decreases below the minimal threshold. This tendency persists with a 20% TLA, demonstrating even lower m-values. TLA has a tendency to enhance the rigidity of the binder, thereby diminishing its capacity to alleviate stress at low temperatures. Introducing CRM into the mix alters the situation. A blend containing 5% CRM exhibits a higher m-value than the original binder, suggesting that CRM boosts the elasticity of asphalt binders and improves their ability to relax tension at low temperatures. When PG 64-22 is combined with both 10% TLA and 5% CRM, the m-value increases in comparison to the blend containing only 10% TLA.