# Evaluation of Aging Resistance of Graphene Oxide Modified Asphalt
## 3 Results and Discussion
### UV Aging Resistance Performance
#### 3.2.3 Evaluating the Rheological Properties
It can be found from this figure that the order of G*sin\(\delta\) after UV aging is 3% GO-modified 90 A < 1% GO-modified 90 A < 90 A, indicating that the GO can improve the anti-fatigue performance of 90 A after UV aging, and the improvement effect of 3% GO is much better than 1% GO. Table 2 shows the FFT of 90 A and SBS MA. It can be observed from Table 2 that, before aging, the FFT of the 1% GO-modified 90 A is the same as the 90 A, and the FFT of the 3% GO-modified 90 A is 0.7 \({}^{\circ}\)C lower than 90 A, so the GO can slightly improve the anti-fatigue performance of 90 A before aging. After TFOT, the FFT of 90 A and the GO-modified 90 A all increased, but the FFT of the 1% and 3% GO-modified 90 A were 2.6 \({}^{\circ}\)C and 0.5 \({}^{\circ}\)C lower than 90 A. This trend was the same for the G and \(\delta\) values. After UV aging, the order of the TTF was found to be 3% GO-modified 90 A < 1% GO-modified 90 A < 90 A. The change above proves that GO can improve the anti-aging performance of an asphalt binder, the fatigue cracking resistance performance of the GO-modified 90 A are better than 90 A at any aging states, and the improvement effect will be more significant after aging. Figure 10: Complex modulus of 90 A and GO modified 90 A after TFOT and nine days of UV aging. The G* and the \(\delta\) of SBS MA and the GO-modified SBS MA before aging and after TFOT are shown in Figure 12. Before aging, the GO did not increase the G* of the SBS MA significantly, the G* curve of GO-modified SBS MA almost overlap with the SBS MA without the GO. With the increase of GO content, the \(\delta\) of the SBS MA only slightly decreases. The slight changes of the G* and the \(\delta\) show the GO will not obviously decrease the low-temperature performance of the SBS MA. After TFOT aging, the G* increases while the \(\delta\) decreases, which shows the increment of the asphalt aging degree. Compared to SBS MA, the G* increment and the \(\delta\) decrement of the GO-modified SBS MA is almost the same, so the GO is not able to improve the thermo-oxidative aging resistance performance of SBS MA significantly. The improvement effect of the GO during TFOT may be weakened by the stirring and film action of the CO\({}_{2}\), and the viscosity of the SBS MA increase more sharply than the 90 A with the decrease of the temperature, which may seal more CO\({}_{2}\) in the asphalt. The CO\({}_{2}\) sealed in the asphalt will be released when the viscosity decreases at high temperature during TFOT. Thus, there is no obvious improvement of the SBS MA anti-TFOT aging performance. The G* and the \(\delta\) of SBS MA and the GO-modified SBS MA after TFOT and after nine days of UV aging are shown in Figure 13. After UV aging, the order of the G* is 3% GO-modified SBS MA \(<\) 1% GO modified SBS MA \(<\) SBS MA, and the G* increment of 3% GO-modified SBS MA is the lowest, 1% GO modified SBS MA is the second and SBS MA is the largest, there is no obvious difference of the \(\delta\) of these three kinds of SBS MA binders. Thus, the order of the anti-UV aging performance is 3% GO-modified SBS MA \(>\) 1% GO-modified SBS MA \(>\) SBS MA. Therefore, one can conclude that, for these binders, GO can improve the anti-UV aging performance of SBS MA and the improvement of the 3% GO is better than that of the 1% GO. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline
**Aging Degree** & \multicolumn{3}{c}{**Virgin**} & \multicolumn{3}{c}{**TFOT Aging**} & \multicolumn{3}{c}{**UV Aging**} \\ \hline GO content (\%) & 0 & 1 & 3 & 0 & 1 & 3 & 0 & 1 & 3 \\ FFT (\({}^{\circ}\)C) & 16.5 & 16.5 & 15.8 & 19.3 & 16.7 & 18.8 & 20.6 & 19.2 & 19.0 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: The FFT of 90 A and GO-modified 90 A.  
Figure 11: Fatigue cracking factor of 90 A and GO-modified 90 A.