## 3 Results and Discussion
### Rheological Characteristics Results (Low Temperature)  
The performance of modified high-performance bituminous binders modified with TLA and SBS was evaluated based on their stiffness, m-value, and statistical analysis. These analyses are crucial for ensuring flexibility, durability, and thermal resistance, which are essential for flexible pavements.  
The stiffness graph (Figure 6) indicates that the unmodified PG64-22 bituminous binder demonstrates a stiffness value of 188 MPa, representing superior flexibility, a critical factor for high-performance binders. The incorporation of TLA slightly reduces stiffness and an increase in TLA content further increases stiffness (180 MPa for 10% TLA and 254 MPa for 20% TLA), showing a marginal compromise in flexibility to enhance durability. The addition of SBS at 5% and 10% further increases stiffness, with combinations such as PG64-22 + 10% TLA + 5% SBS exhibiting 243 MPa. However, these levels still remain acceptable within performance limits for flexible pavements. Interestingly, stiffness decreases significantly at higher SBS levels (e.g., 56.4 MPa for PG64-22 + 10% TLA + 15% SBS), which enhances flexibility but may compromise rutting resistance. The statistical analysis in Table 8 supports these findings, where combinations of TLA and SBS at \(-\)12 \({}^{\circ}\)C show significant differences (\"S\") for stiffness at moderate additive levels, while higher SBS contents result in some non-significant (\"N\") outcomes due to potential phase separation.  
The m-value graph complements these observations by assessing the relaxation potential of the binders (Figure 7). The unmodified PG64-22 binder displays the highest m-value (0.35), indicating superior flexibility and stress relaxation capacity. However, adding TLA reduces the m-value slightly (e.g., 0.276 for 10% TLA and 0.295 for 20% TLA), reflecting the trade-off between increased stiffness and reduced relaxation potential. The addition of SBS further decreases the m-value, particularly at higher concentrations. For instance, PG64-22 + 10% TLA + 10% SBS has an m-value of 0.234, suggesting limited thermal relaxation. Table 9 confirms these trends statistically, showing significant results (\"S\") for m-value reductions at moderate additive levels, while a higher SBS con  
The statistical analysis validates the experimental findings, emphasizing the importance of balancing stiffness and m-value for high-performance binders. Lower stiffness values and higher m-values are preferred for flexible pavements, as they ensure better flexibility and resistance to cracking. The results suggest that TLA and moderate SBS levels (5-10%) strike an optimal balance, providing enhanced durability without compromising flexibility. Excessive SBS content (15%) may improve flexibility but can introduce inconsistencies due to compatibility issues.  
In conclusion, the combination of TLA and SBS modifiers offers a promising approach to developing high-performance asphalt binders. The statistical analyses and performance data confirm the effectiveness of these modifications in achieving the desired balance between flexibility and load resistance. These findings support the use of optimized TLA and SBS combinations for sustainable and durable flexible pavements, advancing pavement engineering practices to meet modern traffic and environmental demands.