## 4 Results and Discussion  
### Basic Property Test Results  
The results of basic property test are shown in Table 5. It is readily seen from this table that the 25 \({}^{\circ}\)C penetration of asphalt was greatly affected following the F-T aging process. From the penetration test, it can be seen that the 25 \({}^{\circ}\)C penetration of unmodified and modified asphalt under F-T aging progress is generally reduced and the decay rate of penetration decreases with the increase of F-T cycles, which may be due to the aging of the asphalt under the F-T aging process. With the development of F-T aging process, the proportion of asphaltenes in asphalt gradually increases, the outer membrane of the micelles becomes thinner, the mutual attraction between the micelles increases, so that the asphalt materials gradually harden, and the penetration gradually decreases. According to the trend of penetration index in Figure 7, it can be found that NHSSMA and CBMA is less sensitive to the F-T aging process than base asphalt, and shows better temperature stability. The difference of PI development trend between modified asphalt and unmodified asphalt is the PI of CBMA and NHSSMA first decreases and then increases with the development of F-T aging process. Moreover, the PI variation of CBMA and NHSSMA is less than that of BA after 30 F-T cycles, which is due to the incorporation of carbon black modified and NHSS. After 10 F-T cycles, the previously formed joint structure between asphalt and NHSS particles was destroyed, resulting in a decrease in the PI value of asphalt. After 30 F-T cycles, the PI value increased due to the aging of the asphalt in the modified asphalt. The penetration index variation of NHSSMA was affected by the interaction of above two conditions under the F-T aging process, which lead to the difference of PI development trends between NHSSMA and BA. The results of softening point test for BA, CBMA and NHSSMA under the F-T aging process are given in Figure 8. It is can be seen from this figure that the softening point of asphalt were greatly affected following the incorporation of modifiers. From the softening point test, it was observed that the softening points of BA, CBMA and NHSSMA increases with the development of F-T cycles. This indicates that the F-T aging progress is beneficial to the high-temperature performance of asphalt. It can also be concluded that the softening point variation of modified asphalt is much less than  
\begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline \multirow{2}{*}{**Materials**} & \multirow{2}{*}{**F-T Cycl-es**} & \multicolumn{4}{c}{**Penetration**} & \multirow{2}{*}{**PI Value-**} & \multirow{2}{*}{**Softening Point**} & **10 \({}^{\circ}\)C** & **Rotational** & \multirow{2}{*}{**Avgino Index**} \\ \cline{3-3} \cline{5-10}  & & & & & & & **Point** \({}^{\circ}\)C & & **Ductility** & **Viscosity** \\ \cline{3-3} \cline{5-10}  & 0 & & & & & & **mm** & & **mpa** & \\ \hline \multirow{4}{*}{**CA**} & 0 & 25.3 & 86.9 & 142.4 & \(-\)1.493 & 44.6 & 1090 & 497.7 & 0 \\  & 10 & 19.8 & 57 & 110 & \(-\)1.319 & 45.8  
unmodified asphalt after 30 F-T cycles, and modified asphalt is not sensitive to F-T aging progress, which is consistent with the penetration test results. The results of ductility test for BA, CBMA and NHSSMA under the F-T aging process are given in Figure 9. It can be seen from Figure 9 that the ductility of all asphalt gradually decreases with the increase of F-T cycles. This is due to the aging of the asphalt caused by F-T aging progress. As the aging process intensifies, the asphalt materials gradually harden, and the ductility of asphalt gradually decreases. The ductility of BA is greater than that of CBMA and NHSSMA under the F-T aging progress, which may be due to the destruction of homogeneity of the asphalt after the incorporation of particulate powder modifier. NHSSMA has the smallest ductility among the three types of asphalt, indicating that NHSSMA is more brittle.