# Performance of Stone Masking Asphalt Mixtures Fabricated by Different Compaction Methods
## 3 Results
### Comparison of Aging Resistance  
As the compaction performs more work in the VVTM than in the Marshall method, the test specimen formed by the VVTM was denser than that formed by the Marshall method, and its optimal asphalt content was smaller. The superior mechanical properties and small asphalt contents of VVTM-designed mixtures have been demonstrated in previous studies, but whether the design method affects the anti-aging performance needs further research and demonstration. Therefore, this subsection simulates the short-term and long-term aging processes of the SMA mixtures in an indoor test, and analyzes the performance changes of the asphalt in the different mixtures. The effect of aging degree on the asphalt performance in the mixtures, and the performance results of the recovered asphalts, are shown in Tables 14 and 15, respectively. In these tables, R represents the asphalt performance, and R\({}_{\text{S}}\) and R\({}_{\text{L}}\) represent the short-term aging and long-term aging performances, respectively. The aging degrees of the mixtures designed by different methods exerted similar influences on the asphalt performance; that is, increasing the aging degree gradually decreased the penetration and ductility of the mixture, and increased its softening point and viscosity. The asphalt performances of mixtures aged to the same degree depended on the design method. The VVTM-designed asphalt mixture exhibited a larger performance change after short-term aging than the other mixtures, indicating a deeper aging degree. However, after long-term aging, the range of the performance change was \begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Asphal Performance**} & \multirow{2}{*}{**Original**} & \multicolumn{2}{c}{**Marshall**} & \multicolumn{2}{c}{**SGC**} & \multicolumn{2}{c}{**VVTM**} \\ \cline{3-8}  & & **R\({}_{\text{S}}\)** & **R\({}_{\text{L}}\)** & **R\({}_{\text{S}}\)** & **R\({}_{\text{L}}\)** & **R\({}_{\text{S}}\)** & **R\({}_{\text{L}}\)** \\ \hline Penetration (0.1 mm) & 65.0 & 53.0 & 45.5 & 52.5 & 44.5 & 50.5 & 44.0 \\ Ductility (cm) & 41.4 & 32.6 & 23.8 & 30.8 & 23.5 & 31.2 & 24.7 \\ Softening point (\({}^{\circ}\)C) & 85.0 & 89.5 & 104.5 & 91.0 & 105.0 & 91.5 & 103.0 \\ Viscosity & 2.0 & 2.4 & 3.1 & 2.5 & 3.2 & 2.5 & 3.0 \\ \hline \hline \end{tabular}
\end{table} 
Table 14: Influence of aging process on the performance of asphalts designed by different methods. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multirow{2}{*}{**Asphal Performance**} & \multicolumn{2}{c}{**Marshall**} & \multicolumn{2}{c}{**SGC**} & \multicolumn{2}{c}{**VVTM**} \\ \cline{2-7}  & **R\({}_{\text{S}}\)/R** & **R\({}_{\text{L}}\)/R** & **R\({}_{\text{S}}\)/R** & **R\({}_{\text{L}}\)/R** & **R\({}_{\text{S}}\)/R** & **R\({}_{\text{L}}\)/R** \\ \hline Penetration (0.1 mm) & 0.82 & 0.70 & 0.81 & 0.68 & 0.78 & 0.68 \\ Ductility (cm) & 0.79 & 0.57 & 0.74 & 0.57 & 0.75 & 0.60 \\ Softening point (\({}^{\circ}\)C) & 1.05 & 1.23 & 1.07 & 1.24 & 1.08 & 1.21 \\ Viscosity & 1.20 & 1.55 & 1.25 & 1.60 & 1.25 & 1.50 \\ \hline \hline \end{tabular}
\end{table} 
Table 15: Comparison of aging performances of SMA-13 asphalt mixtures designed by different methods. smaller in the VVTM-designed mixture than in the Marshall- and SGC-designed mixtures, indicating a smaller degree of long-term aging. This result can again be explained by the smaller amount of asphalt in the VTTM than in the Marshall and SGC methods, meaning a thinner asphalt film in the mixture. Previous studies have shown that the thickness of an asphalt film determines its resistance. The larger the thickness of the asphalt film, the better is the anti-aging performance of the mixture; therefore, the asphalt mixture designed by the VVTM aged to a deeper degree than the other mixtures. In contrast, the long-term aging of asphalt mixtures is mainly affected by external factors such as oxygen, water, and light. Asphalt reacts under the action of hot oxygen and light to form aldehydes, ketones, acids, and alum.