## 3 Results and Discussion  
### Physical Properties  
As shown in Figure 2, the viscosity features of PG 64-22 bituminous binders modified with TLA and SBS polymers were evaluated at 135 \({}^{\circ}\)C and 180 \({}^{\circ}\)C to assess their workability and performance for pavement engineering uses. Statistical analysis results (Table 4) were carried out at a 95% confidence level (\(\alpha\) = 0.05) to determine the significance of differences in viscosity among the modified combinations.  
The unmodified PG 64-22 binder guaranteed good workability by displaying viscosities of 757 cP at 135 \({}^{\circ}\)C and 282 cP at 180 \({}^{\circ}\)C, far below the recommended limit of 3000 cP. With the addition of 10% TLA, the viscosity increased slightly to 856 cP (135 \({}^{\circ}\)C) and 303 cP (180 \({}^{\circ}\)C), and for 20% TLA, values further rose to 872 cP and 311 cP. Statistical analysis showed that these increases were significant (S) compared to the base binder, indicating that TLA enhances viscosity while maintaining workability at these levels.  
When SBS was introduced, the viscosity increased considerably, particularly with a higher SBS content. For instance, with 5% SBS, the viscosities were 2087.5 cP (135 \({}^{\circ}\)C) and 787.5 cP (180 \({}^{\circ}\)C) for 10% TLA and increased to 2512.5 cP and 1025 cP for 20% TLA. Statistical analysis confirmed that the addition of 5% SBS led to significant (S) differences compared to the TLA-only blends. While the viscosities remained below the 3000 cP threshold, they indicated improved stiffness and deformation resistance, making these blends suitable for high-performance pavements.  
At 10% SBS, viscosities exceeded acceptable workability limits, reaching 7212 cP (135 \({}^{\circ}\)C) and 1562.5 cP (180 \({}^{\circ}\)C) for 10% TLA and rising further to 8687.5 cP and 1812.5 cPfor 20% TLA. These increases were statistically significant (S) compared to lower SBS blends, confirming the substantial impact of SBS on binder viscosity. At 15% SBS, the viscosities surged drastically, reaching 13,000 cP (135 \({}^{\circ}\)C) and 2387.5 cP (180 \({}^{\circ}\)C) for 10% TLA, which further escalated for 20% TLA. Statistical analysis indicated that these combinations were significantly different (S) from all other blends, stressing the compromise between lowered workability and better performance.  
The statistical results for viscosity at 180 \({}^{\circ}\)C mirrored the trends observed at 135 \({}^{\circ}\)C (Table 4). Significant increases were noted for all SBS-modified blends compared to the base PG 64-22 and TLA-only combinations. However, at elevated SBS levels (10% and 15%), the viscosities became impractically high, compromising binder workability despite enhanced stiffness and elasticity.  
Overall, the results demonstrate that the combination of 5% SBS with 10-20% TLA is optimal at a temperature of 135 \({}^{\circ}\)C, achieving an acceptable workability for practical pavement applications. Higher SBS content, although beneficial for improving binder performance, introduces significant workability challenges, as reflected in both viscosity data and statistical analysis, and a higher temperature is required to mitigate this issue of workability. These findings underscore the importance of optimizing TLA and SBS proportions to generate excellent asphalt binders fit for long-lasting pavements under high-temperature conditions. Further field studies and construction techniques are recommended to validate the performance of these blends in real-world pavement engineering scenarios.