## 3 Results and Discussion
### Results of MSCR Test on Unaged and Short-Term Aged Binders  
The results of the MSCR test provide important information about the performance of different binders. This includes the original binderPG64-22, as well as its modifications with TLA and further enhancements with SIS. The MSCR test evaluates the performance of these binders in both their unaged state and after short-term aging using the RTFO. Figure 5 and Table 7 demonstrate that the original binder, PG64-22, had the lowest percentage of recovery. Its original state showed a value of 0.04%, which increased to 1.85% after RTFO aging. The low recovery values, along with the highest \(J_{nr}\) values (5.11 kPa\({}^{-1}\) unaged and 1.92 kPa\({}^{-1}\) after aging), suggest a lack of resistance to deformation. The binder's substantial non-recoverable stress when subjected to a load indicates that it is likely to experience rutting and other types of permanent deformation when exposed to traffic loading. When the TLA was added to the PG64-22 binder, there was a slight increase in the % recovery. For example, after undergoing RTFO aging, the PG64-22 + 20% TLA mixture exhibited a small increase in the % recovery to 2.87%, while its \(J_{nr}\) value remained relatively high at 1.47 kPa\({}^{-1}\). This suggests that although TLA improves the performance of the binder to some degree, the enhancement is not significant enough to significantly change the binder's overall ability to resist deformation. \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline  & & \multicolumn{4}{c}{RTFO + PAV Condition at 25 °C} \\ \hline \multicolumn{1}{c}{\multirow{4}{*}{**Combination**}} & \multirow{2}{*}{**PG**} & \multirow{2}{*}{**PG64-**} & \multirow{2}{*}{**PG64-**} & \multirow{2}{*}{**PG64-**} & \multirow{2}{*}{**PG64-**} & \multirow{2}{*}{**PG64-**} & \multirow{2}{*}{**PG64-**} \\  & & & & & & & 22+10\%TLA+5\% & & 22+20\%TLA+5\% & & 22+10\%TLA+10\% \\ \hline \multirow{4}{*}{**STS**} & \multirow{2}{*}{**PS64-22**} & \multirow{2}{*}{-} & \multirow{2}{*}{S} & \multirow{2}{*}{S} & \multirow{2}{*}{S} & \multirow{2}{*}{S} & \multirow{2}{*}{S} \\  & & & & & & & & \\ \cline{1-1} \cline{6-7}  & PG64-22+10\%TLA & - & - & S & S & S & S & S \\ \cline{1-1} \cline{6-7}  & PG64-22+10\%TLA & - & - & S & S & S & S \\ \cline{1-1} \cline{6-7}  & PG64-22+10\%TLA+5\% SIS & - & - & - & S & S & S \\ \cline{1-1} \cline{6-7}  & PG64-22+10\%TLA+10\% SIS & - & - & - & - & - & S \\ \cline{1-1} \cline{6-7}  & PG64-22+20\%TLA+10\% SIS & - & - & - & - & - & - \\ \hline \hline \end{tabular} S–Significant and N–Non-significant.  
\end{table} 
Table 6: Statistical analysis results of the RTFO + PAV of modified asphalt binders at 25 °C as a function of different combinations (\(\alpha\) = 0.05). The introduction of SIS into the binder formulations resulted in the most notable improvements in performance. The inclusion of SIS resulted in significant enhancements in % recovery and reductions in \(I_{nr}\) values, indicating improved elasticity and increased resistance to deformation. As an illustration, the combination of the PG64-22 binder with 10% TLA and 5% SIS showed a significant increase in the percentage of recovery, reaching 16.17% when unaged and 30.92% after undergoing RTFO aging. Simultaneously, the \(J_{nr}\) values experienced a substantial decrease, indicating a notable enhancement in the binder's capacity to regain its original form after being exposed to stress, consequently diminishing permanent deformation. However, a noteworthy pattern arises as the amount of SIS content is further augmented. First, when the SIS content increases, there is a significant improvement in % recovery after aging. This indicates that the binder becomes more resilient and less likely to experience permanent deformation. The reason for this is most likely the formation of an elastomeric network by SIS within the binder matrix. This network enables the binder to deform when subjected to stress and then regain its original shape more efficiently.