## 3 Results and Discussion
### Results of Rheological Properties at High Temperatures  
The study examines the impact of TLA and SIS on the rheological behavior of PG 64-22 asphalt binder, with a specific emphasis on the G*/sin\(\delta\) parameter. This parameter, known as the complex shear modulus (G*) combined with the phase angle (\(\delta\)), is a crucial indicator of a pavement's capacity to withstand deformation, particularly in high-temperature conditions. A higher G*/sin\(\delta\) value signifies enhanced resistance to rutting, a prevalent and detrimental type of permanent deformation in asphalt pavements.  
Figure 3 and Table 5 demonstrate that the base binder, PG 64-22, shows the lowest G*/sin\(\delta\) values in both its original and RTFO-aged conditions. Without any alterations, PG 64-22 exhibits limited resistance to deformation at elevated temperatures, rendering it unsuitable for environments where rutting is a significant issue.  
TLA implementation in PG 64-22 results in a significant enhancement in the binder's efficacy. For example, when 10% TLA is added, the G*/sin\(\delta\) values of the original binder increase from 2.05 kPa (original) and 5.35 kPa (RTFO) to 2.55 kPa and 5.90 kPa, respectively. By increasing the TLA content to 20%, the binder's stiffness and rutting resistance are further improved, as indicated by the values of 3.10 kPa (original) and 6.50 kPa (RTFO). The results demonstrate that TLA, a naturally occurring asphalt, greatly enhances the binder's capacity to withstand deformation.  
The most notable enhancements are observed when SIS is added, especially when combined with TLA. Adding 5% SIS to the PG 64-22 + 10% TLA binder significantly enhances the G*/sin\(\delta\), which reaches 8.14 kPa (original) and 15.30 kPa (RTFO). When the SIS content is increased to 10%, the G*/sin\(\delta\) values significantly increase to 12.10 kPa (original) and 20.80 kPa (RTFO). This illustrates that the use of SIS is crucial in improving the binder's ability to withstand deformation.  
In this study, it was found that the binder with 20% TLA and 10% SIS had the highest G*/sin\(\delta\) values, with 26.50 kPa (original) and 33.10 kPa (RTFO). These findings indicate that the simultaneous application of TLA and SIS produces a synergistic outcome, resulting in a notable enhancement in the stiffness and resistance to rutting of the binder. This makes it particularly well suited for pavements that are exposed to elevated temperatures.  
The enhancements observed with the incorporation of SIS can be ascribed to its distinctive polymeric architecture. SIS, being a thermoplastic elastomer, improves the elasticity and stiffness of the binder. This enables the binder to retain its structural integrity when subjected to load, especially in high-temperature conditions. This leads to increased G*/sin\(\delta\) values, which indicate a greater ability to withstand permanent deformation or rutting. This is a crucial factor for the long-term durability and lifespan of asphalt pavements.  
To summarize, the results of this study clearly show that adding SIS to TLA-modified PG 64-22 binders greatly improves the flow characteristics of the asphalt, making it more resistant to deformation at high temperatures. The significant enhancements in G*/sin\(\delta\) observed in different compositions highlight the crucial role of SIS in enhancing pavement performance, making it a valuable additive for achieving more durable and resilient asphalt pavements.