## 4 Results and Discussion
### Temperature Sweep Test  
The temperature sweep tests of unaged and RTFO-aged matrix asphalts and bio-asphalt binders were carried out, and the complex modulus G*, phase angle 8, and rutting factor G*/sin \(\delta\) were analyzed. As seen in Figure 7a,b, for unaged asphalt, the phase angle of bio-asphalts with 5% and 10% bio-oil content, and 10%-S, gradually increased with the increase of temperature; this indicated that the viscous component increased with increasing temperature. However, the phase angle of 50# matrix asphalt and 5%-S reached a maximum at 64 \({}^{\circ}\)C, indicating that the viscous components also reached a maximum at that temperature. The phase angle of bio-asphalt with 30% content bio-oil had a smaller downward trend; this was due to the excessive variability of the bio-oil. Compared with 50# base asphalt, the phase angles of unaged bio-asphalt with 5% and 10% bio-oil were both higher than the base asphalt, while the phase angle of bio-asphalt with 30% bio-oil was lower than that of the base asphalt. This indicated that the viscous components of bio-asphalt increased with the increase of the 5% and 10% bio-oil content, and that the high-temperature performance was affected by the bio-oil. The bio-asphalt with 30% bio-oil content reduced; this was caused by the extreme variability of the 30% bio-oil. For the RTFO-aged asphalt, the phase angle of bio-asphalt increased with the increase of temperature, and the phase angles of bio-asphalt with 5% and 10% content bio-oil were lower than those of the matrix asphalt when the temperature was lower than 70 \({}^{\circ}\)C, while they were higher when the temperature was greater than 70 \({}^{\circ}\)C. This indicated that when the temperature was greater than 70 \({}^{\circ}\)C, the incorporation of 5% and 10% of the bio-oil would increase the viscosity of the bio-asphalt. Meanwhile, the phase angle of the bio-asphalt with 30% bio-oil content was higher than that of the matrix asphalt and of the bio-asphalts with 5% and 10% content bio-oil, indicating that it had a larger viscous component, and that it had lower high temperature performance. The phase angles of bio-asphalt 5%-S and 10%-S were lower than those of other bio-asphalts, due to the elasticity of SBS. As shown in Figure 8a,b, for the unaged and RTFO-aged asphalts, the complex modulus of bio-asphalt decreased with the increase of temperature; this indicated that, with the increase of temperature, the asphalt became soft, and its resistance to rutting declined. The sequence of complex modulus for the unaged and RTFO-aged asphalt were G* (50#) > G* (5%) = G* (10%) > G* (30%), G* (30%) > G* (10%) > G* (5%) = G* (50#), respectively. The results showed that the complex modulus of bio-asphalts without SBS decreased with an increase of bio-oil content. After short-term aging, the sequence was opposite to that of the unaged asphalt. This indicated that the bio-asphalt became softer with the addition of bio-oil for the unaged, and harder for the RTFO-aged; the results were consistent with those of the conventional tests. This was due to the aging of the bio-asphalt after the addition of  
Figure 7: The relationship between phase angle and temperature. (**a**) Unaged; (**b**) RTFO aged. significant quantities of bio-oil. The modulus of 5%- and 10%-S were improved more than those of the bio-asphalts with 5% and 10% bio-oil, but the action of SBS was different, based on the bio-oil content and RTFO aging. Figure 9a,b shows the relationship between rutting factors and temperature. The changes of the rutting factors of bio-asphalt and matrix asphalt were relatively consistent with the changes of complex modulus. The sequence of rutting factors for the unaged and RTFO-aged asphalts were G*/sin\(\delta\) (50\(\theta\)) > G*/sin\(\delta\) (5%) = G*/sin\(\delta\) (10%) > G*/sin\(\delta\) (30%) and G*/sin\(\delta\) (30%) > G*/sin\(\delta\) (10%) > G*/sin\(\delta\) (5%) = G*/sin\(\delta\) (50\(\theta\)), respectively. The changes were also consistent with the changes of complex modulus.