## 4 Results and Discussion
### Conventional Tests
Referring to the RTFO-aged bio-asphalt, with an increase in bio-oil content, ductility decreased, indicating that the asphalt became relatively hard after short-term aging. However, for 5%-S and 10%-S, the ductility indicated that SBS could also improve the low temperature properties of RTFO-aged bio-asphalt binders. Mass losses between unaged and RTFO-aged bio-asphalt are shown in Figure 6. With the increase of bio-oil content, the mass loss of bio-asphalt increased. This showed that the addition of bio-oil made the mass of bio-asphalt decrease at 163 \({}^{\circ}\)C. This was due to the volatilization of light components, and the aging of the asphalt. Meanwhile, the greater the amount of bio-oil, the more aging occurred. However, for 5%-S and 10%-S, the mass loss was lower than 5% and 10% of the bio-oil content, which means that the incorporation of SBS would decrease the aging of bio-asphalt. The mass loss of bio-asphalt with 5% bio-oil content was \(-\)0.580%, which could meet the requirements described in the Technical Specifications for Construction of Highway Asphalt Pavements (JTG  
Figure 4: Softening point of unaged and RTFO aged bio-asphalt. Figure 5: Ductility of unaged and RTFO aged bio-asphalt. and 10%-S could also meet these specifications. However, the mass loss of bio-asphalt with 10% and 30% content bio-oil would not meet the requirements. It was found that the incorporation of bio-oil had a great influence on the mass loss of the bio-asphalt, but that the effect of different dosages was unknown. To identify the difference between the different types of asphalt, and to understand the significant changes in the mass of bio-asphalt with varying bio-oil contents, the LSD (Least Significant Difference) method was used. The LSD method is the most sensitive of the various multi-comparison methods. It is able to detect small differences between groups. The analysis through LSD of the effects of different bio-oil contents on mass loss is shown in Table 1.  
According to the results of the LSD analysis, it could be seen that the significance between the various asphalts was less than 0.05, which indicates that the change of bio-oil content had a significant effect on the mass loss. \begin{table}
\begin{tabular}{c c c c c c c} \hline \multirow{2}{*}{**Content of Bio-oil**} & **Content of Bio-Oil** & **Mean Difference** & **Standard Error** & \multirow{2}{*}{**Significance**} & \multirow{2}{*}{**95\% Confidence Interval**} \\ \cline{3-3} \cline{5-6}  & 5\% & \(-0.294000\) * & 0.052726 & & & **Lower Limit** & **Upper Limit** \\ \hline \multirow{3}{*}{0\%} & 5\% & \(-0.294000\) * & 0.052726 & 0.001 & \(-0.41559\) & \(-0.17241\) \\  & 10\% & \(-1.180000\) * & 0.052726 & 0.000 & \(-1.30159\) & \(-1.05841\) \\  & 30\% & \(-3.836000\) * & 0.052726 & 0.000 & \(-3.95759\) & \(-3.71441\) \\ \hline \multirow{3}{*}{5\%} & 0\% & 0.294000 * & 0.052726 & 0.001 & 0.17241 & 0.41559 \\  & 10\% & \(-0.886000\) * & 0.052726 & 0.000 & \(-1.00759\) & \(-0.76441\) \\  & 30\% & \(-3.542000\) * & 0.052726 & 0.000 & \(-3.66359\) & \(-3.42041\) \\ \hline \multirow{3}{*}{10\%} & 0\% & 1.180000 * & 0.052726 & 0.000 & 1.05841 & 1.30159 \\  & 5\% & 0.886000 * & 0.052726 & 0.000 & 0.76441 & 1.00759 \\  & 30\% & \(-2.656000\) * & 0.052726 & 0.000 & \(-2.77759\) & \(-2.53441\) \\ \hline \multirow{3}{*}{30\%} & 0\% & 3.836000 * & 0.052726 & 0.000 & 3.71441 & 3.95759 \\  & 5\% & 3.542000 * & 0.052726 & 0.000 & 3.42041 & 3.66359 \\ \cline{1-1}  & 10\% & 2.656000 * & 0.052726 & 0.000 & 2.53441 & 2.77759 \\ \hline \end{tabular}
\end{table} 
Table 1: Analysis through LSD (Least Significant Difference) of the effects of different bio-oil contents on mass loss. Figure 6: Mass loss between unaged and RTFO aged bio-asphalt.