# Preparation and Properties of SBS/REOB-Modified Rejuvenated Asphalt
## 5 Conclusions  
1. Based on the orthogonal test, SBS/REOB-modified rejuvenated asphalt was prepared, and it was determined that the performance indicators of the SBS/REOB-modified rejuvenated asphalt reached the optimal combination of 9% REOB + 4.5% SBS. The process conditions were a shear time of 40 min and a shear rate of 5000 r/min.
2. Through a DSR test, SBS modification of REOB rejuvenated asphalt obtained the same excellent high-temperature performance as ordinary SBS-modified asphalt. The rutting resistance of the modified rejuvenated asphalt was further improved. The rutting resistance of 4.5% SBS + 9% REOB at 46 \({}^{\circ}\)C was more than 65% higher than that of rejuvenated asphalt; compared with the base asphalt, it also improved about 42%. Frequency scanning shows that the modified rejuvenated asphalt presented a low \(G^{\star}\) value at high temperature and low frequency, and a high \(G^{\star}\) value at low temperature and high frequency, indicating that it had a certain dependence on temperature and loading frequency.
3. The BBR test showed that the REOB content remained unchanged at 9%. Within the range of SBS content 3.5-4.5%, the higher the content, the better the low-temperature performance of the modified rejuvenated asphalt. When the SBS content was kept unchanged at 4.5%, it was found that in the range of 7-9% REOB content, the low-temperature performance of asphalt increased with the increase in REOB, while the low-temperature cracking resistance decreased when the content was increased to 11%, indicating that the saturated REOB regenerated agent had the opposite effect on the low-temperature performance of asphalt.
4. The fluorescence microscopic test showed that an insufficient shear rate and shear time led to uneven dispersion of the SBS modifier and a poor modification effect. The SBS-modified new asphalt and the modified rejuvenated asphalt prepared in the laboratory had continuous asphalt phases, and the microstructure of the two was similar. SBS was uniformly suspended in the asphalt phase, forming a network structure with the asphalt, and the SBS phase in the modified rejuvenated asphalt basically reached the level of the finished modified asphalt.  
Figure 7: Fluorescence microstructure images of different asphalt samples.  
**Author Contributions:** Conceptualization, Y.C. and L.Z.; methodology, M.Y.; software, S.Z.; validation, X.C., Y.C. and P.L.; formal analysis, J.L.; investigation, J.L.; resources, J.L.; data curation, Y.C.; writing--original draft preparation, Y.C.; writing--review and editing, Y.C.; visualization, L.Z.; supervision, J.L.; project administration, S.Z.; funding acquisition, P.L. All authors have read and agreed to the published version of the manuscript.  
**Funding:** This research was funded by the Natural Science Foundation of Shandong Province, grant number ZR2016 EEM42.  
**Institutional Review Board Statement:** Not applicable.  
**Informed Consent Statement:** Not applicable.  
**Data Availability Statement:** The experimental data in this paper are from the pavement material laboratory of Shandong Jiaotong University, which is the provincial key laboratory.  
**Conflicts of Interest:** The authors declare that they have no conflict of interest regarding the publication of this paper.