## 4 Conclusions  
The study investigated the effects of incorporating different proportions of Trinidad Lake Asphalt (TLA) and styrene-isoprene-styrene (SIS) into a PG 64-22 asphalt binder. The objective was to evaluate the impact of these additives on the performance of the binder, specifically in relation to physical and rheological parameters as per the Superpave test method. The study offers valuable insights into the impact of SIS on the overall performance of the binder. These insights can guide the selection of the most suitable formulations for various pavement engineering applications.  
1. The blend of 20% TLA and 5% SIS provides an optimal balance between workability and enhanced performance. This formulation significantly improves elasticity, while maintaining viscosity within critical limits, making it an ideal choice for durable pavements with excellent resistance to high-temperature deformation, without compromising ease of construction.
2. The combination of 20% TLA and 10% SIS yields the highest G*/sin$ values, indicating superior resistance to cutting under high-temperature conditions making it particularly suitable for pavements in challenging environments requiring long-term resistance to deformation.
3. The 10% TLA and 10% SIS formulation strikes a balance between stiffness and fatigue resistance, enhancing the binder's viscoelastic properties. This combination improves the pavement's ability to resist oxidative aging and mitigates fatigue cracking, ensuring a more durable pavement structure over time.
4. Finally, 10% TLA and 5% SIS display promising results in the MSCR test, showing significant improvements in elasticity and resistance to permanent deformation. This combination is particularly well suited for high-traffic pavements, offering an optimal balance between rigidity and flexibility, ultimately improving pavement durability and overall performance.
5. Although SIS typically improves performance, excessive concentrations can result in excessive stiffness, necessitating careful optimization to strike a balance between enhanced performance and manageable workability.  
The results indicate that the performance of the binder is improved by SIS. However, the selection of the best combination should consider the specific environmental conditions and performance needs. This will ensure that the advantages of SIS are fully utilized without compromising other important properties. Additional research should examine the enduring consequences of these alterations and explore alternative combinations of additives with SIS to further enhance low-temperature performance.  
Conceptualization, S.V. and S.-J.L.; Methodology, S.V.; Validation, J.Y.; Formal analysis, S.V. Resources, M.-S.L.; Writing--original draft, S.V.; Writing--review & editing, S.V. and S.-J.L.; Supervision, J.Y., H.K. and S.-J.L.; Project administration, H.K. and S.-J.L.; Funding acquisition, M.-S.L. and S.-J.L. All authors have read and agreed to the published version of the manuscript. This research was supported by a grant from a government funding project (2024 National Highway Pa  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The data used to support the findings of this study are included within the article.  
**Conflicts of Interest:** There are no conflicts of interest regarding the publication of this paper.