## 3 Test Results, Analyses, and Discussion
### Rheological Properties
#### 3.1.1 Temperature Sweep Analysis  
The DSR temperature sweep tests were conducted with an isochronal plot to evaluate the temperature sensitivity of the asphalt-binder. The complex shear modulus (\(G^{*}\)) and phase angle (\(\delta\)) were measured for subsequent computation of the analyzed rutting factor (\(G^{*}\)/sin\(\delta\)) and fatigue factor (\(G^{*}\)-sin\(\delta\)). The rutting factor (\(G^{*}\)/sin\(\delta\)) reflects the deformation resistance of asphalt-binders at high temperatures [21]. Asphalt-binders with larger rutting factors have better rutting resistance at high temperatures. Figure 4 shows that the \(G^{*}\)/sin\(\delta\) values of the rejuvenated asphalt-binders decreased with an increase in temperature, and that the logarithm of \(G^{*}\)/sin\(\delta\) had a linear correlation with temperature. After the second rejuvenation cycle, the \(G^{*}\)/sin\(\delta\) values of the asphalt-binders with Type I and Type III rejuvenators were comparatively close to those of the RTFO residue. However, only the third rejuvenated SBSMA with Type I rejuvenator had a \(G^{*}\)/sin\(\delta\) that was approximately equivalent to that of the RTFO residue. The superiority rank order of the rutting factors of the first, second, and third rejuvenated asphalt-binders was Type II \(>\) Type I \(>\) Type III, respectively. With an increase in the rejuvenation cycles, the rutting factor of the rejuvenated asphalt-binder with the Type II rejuvenator increased steadily, while that with the Type III rejuvenator decreased. Notably, the rutting factor of the aged SBSMA could be rejuvenated close to that of the RTFO residue by adding the Type I rejuvenator. As the rejuvenation cycles increased, the dispersion of the rutting factor increased, indicating that repeated rejuvenation had a great influence on asphalt-binder's rutting resistance. In general, the following was observed: (a) Type II rejuvenator enhanced the rutting resistance of the asphalt-binder, (b) Type III rejuvenator exhibited the potential to reduce the rutting resistance, and (c) Type I rejuvenator indicated the potential to help maintain the rutting resistance of the rejuvenated asphalt-binder. The fatigue factor (\(G^{*}\)-\(\sin\)\(\delta\)) reflects the anti-fatigue property of the asphalt-binder at intermediate temperatures [21]. Figure 5a,b show that the fatigue factors of the aged asphalt-binders decreased with an increase in temperature, and that the logarithm of \(G^{*}\)-\(\sin\)\(\delta\) had a linear correlation with temperature. The \(G^{*}\)-\(\sin\)\(\delta\) values of the second aged asphalt-binders with the three rejuvenators were close to that of the first aged asphalt-binder, whereas only the third aged SBSMA with Type I rejuvenator had nearly the same values as that of the PAV residue. Figure 4: Rutting factor of SBS asphalt-binders at different rejuvenation cycles: (a) First cycle; (b) Second cycle; (c) Third cycle. From Figure 5, the fatigue factors of the third aged asphalt-binders ranked as follows: Type II > Type I > Type III. The fatigue property of the third aged asphalt-binders with the Type I rejuvenator was closest to that of the PAV residue, whilst that with the Type II rejuvenator was deemed as poor. The Type III rejuvenator, on the other hand, was found to be satisfactory and better than the other two types in terms of potential for fatigue resistance. It was interesting to note that the widest dispersion of the fatigue factor was produced by the third aged asphalt-binders, followed by the second aged asphalt-binders as shown in Figure 5, indicating that the repeated aging process had a great influence on the rheological properties of the SBSMA. By comparison, the fatigue factor of the second and third aged asphalt-binders with the Type I rejuvenator were seen to be close to those of the PAV residue. This observation suggested that the expected rejuvenation performance can be achieved by blending with the Type I rejuvenator.