# Mechanism of Rejuvenation in Aged SBS-Modified Asphalt by Density Functional Theory
## 4 Results and Discussion
### Single-Point Energy (E\({}_{single}\)) and Binding Energy (E\({}_{binding}\))
The interaction between asphaltene and aromatic components was stable. In the long-term aging process, the content of aromatic components and resins was insufficient to promote the aggregation of asphaltene, which tend to combine with each other. More aromatic components started to interact with resins, and the interaction potential between aromatic components and asphaltene decreased. It was also found that asphalt aging level affected the interaction between aromatic components in rejuvenator and asphaltene in aged asphalt. The interaction potential between aromatic components in rejuvenator and asphaltene in short-term aged asphalt in descending order were: asphaltene-thiophene (0.096 Ha) > asphaltene-phenol (0.091 Ha) > asphaltene-pyrrole (0.079 Ha). However, as for long-term aged asphalt, the order changed to: asphaltene-pyrrole (0.046 Ha) > asphaltene-phenol (0.030 Ha) > asphaltene-thiophene (0.027 Ha). \begin{table}
\begin{tabular}{c c} \hline \hline
**Properties** & \(\mathbf{E_{\text{binding}}/\text{Ha}}\) \\ \hline Saturate—Thioisorenieratane (S) & 0.200 \\ Saturate—Asphaltene-phenol (S) & 0.168 \\ Saturate—Asphaltene-pyrrole (S) & 0.157 \\ Saturate—Benzobisbenzothiophene (S) & \(-\)0.132 \\ Saturate—Asphaltene-thiophene (S) & \(-\)0.034 \\ Saturate—Quinolinolopane (S) & \(-\)0.028 \\ Saturate—Pyridinobapane (S) & \(-\)0.015 \\ Saturate—Trimethylbenzeneoxane (S) & 0.006 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: \(E_{\text{binding}}\) between saturate components in rejuvenator and heavy components in short-term aged asphalt. \begin{table}
\begin{tabular}{c c} \hline \hline
**Properties** & \(\mathbf{E_{\text{binding}}/\text{Ha}}\) \\ \hline Saturate—Asphaltene-thiophene (L) & 0.279 \\ Saturate—Asphaltene-phenol (L) & 0.105 \\ Saturate—Asphaltene-pyrrole (L) & 0.098 \\ Saturate—Quinolinolopane (L) & 0.092 \\ Saturate—Benzobisbenzothiophene (L) & 0.085 \\ Saturate—Thoisorenieratane (L) & \(-\)0.063 \\ Saturate—Pyridinobapane (L) & \(-\)0.037 \\ Saturate—Trimethylbenzeneoxane (L) & 0.037 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: \(E_{\text{binding}}\) between saturate components in rejuvenator and heavy components in long-term aged asphalt. \begin{table}
\begin{tabular}{c c} \hline \hline
**Properties** & \(\mathbf{E_{\text{binding}}/\text{Ha}}\) \\ \hline Aromatic—Thioisorenieratane (L) & 0.211 \\ Aromatic—Pyridinobapane (L) & 0.107 \\ Aromatic—Benzobisbenzothiophene (L) & \(-\)0.094 \\ Aromatic—Asphaltene-pyrrole (L) & \(-\)0.046 \\ Aromatic—Quinolinolopane (L) & \(-\)0.033 \\ Aromatic—Asphaltene-phenol (L) & 0.030 \\ Aromatic—Asphaltene-thiophene (L) & \(-\)0.027 \\ Aromatic—Trimethylbenzeneoxane (L) & \(-\)0.026 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: \(E_{\text{binding}}\) between aromatic components in rejuvenator and heavy components in long-term aged asphalt. Table 8 presents \(E_{\text{binding}}\) between aromatic and saturate components in rejuvenator with SBS and its aging products. The conclusion can be summarized that compared with most asphalt components, SBS had better interaction potential with aromatic components of rejuvenator. So, some aromatic components would react with SBS first, after rejuvenator was added into aged and SBS-modified asphalt. To a certain extent, it could weaken the rejuvenation of aged asphalt.