## 3 Results and Discussion
### TPCB's Effect on the Performance of Asphalt
#### 3.2.2 TPCB's Effect on the Rheological Properties of Asphalt  
(1) Complex Modulus and Phase Angle  
An asphalt binder must have enough elasticity to satisfy the requirements of anti-rutting at high temperatures, while having enough plasticity to avoid cracks at low temperatures. The viscoelastic properties of the asphalt binder are important to the pavement performance of asphalt mixtures [33; 34; 35]. In order to study the TPCB effect on the rheological properties of GF-70, the complex modulus (G*) and phase angle (\(\delta\)) of asphalt binders without and with TPCB were studied by the DSR. The parameter G* can estimate the deformation resistance of an asphalt binder under repeated shear loading, and \(\delta\) can reflect the ratios of the elastic and viscous characteristics of an asphalt binder [36; 37]. G* and \(\delta\) of asphalt binders without and with TPCB are shown in Figure 5.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Asphalt**} & \multicolumn{2}{c}{**25 \({}^{\circ}\)C**} & \multirow{2}{*}{**Softening Point (\({}^{\circ}\)C)**} & \multirow{2}{*}{**10\({}^{\circ}\)C**} & \multirow{2}{*}{**PI**} & \multirow{2}{*}{**T\({}_{800}\) (\({}^{\circ}\)C)**} & \multirow{2}{*}{**T\({}_{1.2}\) (\({}^{\circ}\)C)**} & \multirow{2}{*}{**Softening Point Difference (\({}^{\circ}\)C)**} \\  & **Penetration** & & & & & & \\  & **Point (\({}^{\circ}  
It can be seen from Figure 5 that the G* of TPCB/GF-70 is bigger than that of GF-70 in the temperature range \(-\)10-30 \({}^{\circ}\)C, and the same tendency can be observed in the temperature range 30-85 \({}^{\circ}\)C, indicating that a 15% dosage of TPCB can improve the repeated shear deformation resistance of GF-70. From Figure 5a, when the temperature is lower than 0 \({}^{\circ}\)C, the \(\delta\) of TPCB/GF-70 is smaller than that of GF-70; when the temperature is higher than 0 \({}^{\circ}\)C, the opposite occurs. From Figure 5b, the \(\delta\) of TPCB/GF-70 is bigger than that of GF-70 in the temperature range 30-85 \({}^{\circ}\)C, which shows that the elastic characteristic of TPCB/GF-70 is more obvious than that of GF-70 when the temperature is lower than 0 \({}^{\circ}\)C; the viscous ratio of G* of TPCB/GF-70 is higher than that of GF-70 when the temperature is higher than 0 \({}^{\circ}\)C.  
(2) Putting Factor and Fatigue Factor  
The rutting factors (G*/sin\(\delta\)) of GF-70 and TPCB/GF-70 are shown in Figure 6a. The higher the G*/sin\(\delta\), the better the high-temperature anti-rutting performance of an asphalt binder. The G*/sin\(\delta\) of TPCB/GF-70 is higher than that of GF-70 in the high-temperature range of 52 \({}^{\circ}\)C-82 \({}^{\circ}\)C, indicating that a 15% dosage of TPCB can improve the anti-rutting performance of GF-70. In order to ensure an asphalt binder has good rutting resistance, the G*/sin\(\delta\) before aging should not be lower than 1.0 kPa. When the temperature is 69.1 \({}^{\circ}\)C, the G*/sin\(\delta\) of GF-70 is 1.0 kPa, while the G*/sin\(\delta\) of TPCB/GF-70 is 1.0 kPa at a temperature of 70.3 \({}^{\circ}\)C, which is 1.2 \({}^{\circ}\)C higher than that of GF-70. So the high-temperature performance of TPCB/GF-70 is better than that of GF-70. The fatigue factors (G*sin\(\delta\)) of GF-70 and TPCB/GF-70 are shown in Figure 6b. The lower the G*sin\(\delta\), the better the anti-fatigue cracking performance of an asphalt binder. The G*sin\(\delta\) of GF-70 becomes higher after being mixed with a 15% dosage of TPCB in the middle temperature range of 19-40 \({}^{\circ}\)C, so that when the temperature is 22 \({}^{\circ}\)C, the G*sin\(\delta\) of TPCB/GF-70 is 19.6% higher than that of GF-70, indicating that TPCB can decrease the anti-fatigue cracking performance of GF-70.