# Preparation and Properties of SBS/REOB-Modified Rejuvenated Asphalt
## 4 Results and Analysis
### Dynamic Shear Rheological Test  
#### 4.2.1 Temperature Characteristics  
Complex Modulus and Phase Angle  
Figure 3 shows that the G* of 4.5% SBS + base asphalt was slightly lower than that of ordinary SBS, and the G* values of the two gradually tended to be the same after 70 \({}^{\circ}\)C. In addition, the \(\delta\) values of the two were also close to the changing trend, indicating that the quality of asphalt samples prepared in the laboratory was slightly worse than that of ordinary SBS-modified asphalt purchased in the market. However, from another point of view, it was also verified that the preparation of modified asphalt under this condition was feasible. As can be seen from Figure 2(a), the G* value decreased regularly with the increase in temperature, and the decreasing rate decreased accordingly. In the temperature range from 46 \({}^{\circ}\)C to 70 \({}^{\circ}\)C, the G* value of the five asphalts in descending order was as follows: ordinary SBS >4.5% SBS + base asphalt > 4.5% SBS + 9% REOB + aged asphalt > base asphalt >9% REOB + aged asphalt. Compared with conventional asphalt and reclaimed asphalt, the G* value of 9% REOB + aged asphalt was lower than that of the base asphalt. However, the G* value of the 4.5% SBS + 9% REOB + aged asphalt modified rejuvenated asphalt after modification was significantly increased, indicating the stable cross-linking network structure formed between SBS and asphalt; therefore, it had better deformation resistance. When the test temperature exceeded 64 \({}^{\circ}\)C, the G* of base asphalt was about 9% REOB + aged asphalt, and when the test temperature exceeded 82 \({}^{\circ}\)C, the G* of 4.5% SBS + 9% REOB + aged asphalt decreased to the same level as the base asphalt. The results show that the SBS/REOB-modified asphalt had a high deformation resistance at high temperature and good temperature sensitivity. Figure 2(b) shows that the \(\delta\) values rose with the increase in temperature, but the increase in \(\delta\) was different for different asphalts. The \(\delta\) temperature curves of different asphalts in Figure 2(b) show that the phase angle of 9% REOB + aged asphalt was at a high level after 46 \({}^{\circ}\)C, indicating that the viscous component played a major role in the asphalts after 46 \({}^{\circ}\)C, while the \(\delta\) of 4.5% SBS + 9% REOB + aged asphalt was almost at the level of 9% REOB + aged asphalt from 52 \({}^{\circ}\)C to 88 \({}^{\circ}\)C. In addition, its growth rate was similar to the modified new asphalt 4.5% SBS + base asphalt and ordinary SBS, indicating that the SBS modification of the REOB rejuvenated asphalt obtained the same excellent high-temperature performance as the ordinary SBS-modified asphalt. Figure 3: (a) Variation of G* with temperature; (b) Variation of \(\delta\) with temperature. Rutting Factor and Critical Temperature  
The rutting factor (\(G^{*}\)/sin\(\delta\))-temperature curve in Figure 4 was used to compare the difference in the high-temperature rutting resistance of REOB rejuvenated asphalt before and after SBS modification. The rutting factor \(G^{*}\)/sin\(\delta\) was determined by the complex modulus \(G^{*}\) and phase angle \(\delta\); therefore, it accurately reflected the high-temperature performance of asphalt. The variation laws of rutting factor \(G^{*}\)/sin\(\delta\) and complex modulus \(G^{*}\) are similar: \(G^{*}\)/sin\(\delta\) decreased with the increase in temperature and REOB content. The higher the aging degree of the asphalt, the better its rutting resistance; namely, the aging matrix asphalt \(G^{*}\)/sin\(\delta\) value was larger than the original asphalt [11].