# Preparation and Properties of SBS/REOB-Modified Rejuvenated Asphalt
## 4 Results and Analysis  
### Orthogonal Test  
The orthogonal test results are shown in Table 8.  
The analysis of the orthogonal test results is shown in Table 9, where \(K_{i}\) represents the sum of the corresponding experimental results when the level number in any column was \(i\), \(i=1\), \(2\), \(3\); \(\overline{K_{i}}\) represents the arithmetic mean of the results obtained at factor level \(i\), \(i=1\), \(2\), \(3\); and \(R\) represents the range of the test results. The range calculation results are shown in Table 9.  
The influence factors of the change in each factor level on the results are reflected by the range. The larger the range, the more obvious the influence of this factor on the results within the scope of the test. The degree of penetration represents the degree of softness and hardness of asphalt, but also reflects the relative viscosity of the asphalt under certain conditions; the smaller the value is, the harder the asphalt, the better the viscosity, and vice versa. It can be seen from the results of the needle penetration range that SBS content was the main factor affecting the viscosity of the composite modified asphalt [11]. In order to obtain SBS/REOB-modified rejuvenated asphalt with better viscosity, scheme A\({}_{3}\)B\({}_{5}\)C\({}_{3}\)D\({}_{3}\) should be selected; that is, the optimal dosage of REOB and SBS was 7% and 4.5%. \begin{table}
\begin{tabular}{c c c} \hline
**Name of Test** & **The Asphalt** & **Test Indicators** \\ \hline DSR temperature scan & Original asphalt & Phase Angle \(\delta\), complex shear modulus \(G^{\star}\), \\   DSR frequency scanning & Original asphalt & \multicolumn{2}{c}{} \\   Bending creep stiffness test (BBR) & PAV(Pressure Aging Vessel) aged asphalt & \multicolumn{2}{c}{} \\  & & & \\ \end{tabular}
\end{table} 
Table 7: Test scheme of asphalt rheological properties. \begin{table}
\begin{tabular}{c c c c c c c c} \hline
**Test Group** & **REOB** & **SBS** & **Shear** & **Shear Rate** & **Needle Penet-** & **Softening** & **Extension** & **Elastic Re-** \\  & **Dosage** & **Dosage** & **Time/Min** & **/(r/min)** & **tration/mm** & **Point/\({}^{o}\)C** & **/cm** & **covery/\%** \\ \hline
1 & 1 (11\%) & 1 (3.5\%) & 1 (40) & 1 (4000) & 84 & 56.5 & 23.9 & 79 \\
2 & 1 (11\%) & 2 (4.0\%) & 2 (50) & 2(4500) & 80.2 & 61.2 & 25.2 & 85 \\
3 & 1 (11\%) & 3 (4.5\%) & 3 (60) & 3 (5000) & 63.8 & 61.9 & 29.3 & 82 \\
4 & 2 (9\%) & 1 (3.5\%) & 2 (50) & 3 (5000) & 78.3 & 57.7 & 26.5 & 81 \\
5 & 2 (9\%) & 2 (4.0\%) & 3 (60) & 1 (4000) & 79.1 & 62.3 & 27.2 & 86 \\
6 & 2 (9\%) & 3 (4.5\%) & 1 (40) & 2 (4500) & 64.5 & 63.7 & 33.4 & 89 \\
7 & 3 (7\%) & 1 (3.5\%) & 3 (60) & 2 (4500) & 76.9 & 58.3 & 24.8 & 79 \\
8 & 3 (7\%) & 2 (4.0\%) & 1 (40) & 3 (5000) & 76 & 62.1 & 29.8 & 88 \\
9 & 3 (7\%) & 3 (4.5\%) & 2 (50) & 1 (4000) & 62.7 & 63.2 & 30.5 & 81 \\ \hline \end{tabular}
\end{table} 
Table 8: Orthogonal test results. The softening point is an index to measure the conditional viscosity of asphalt, which can be used to characterize the high-temperature stability of modified rejuvenated asphalt. The range of the softening point was \(\rm{R_{B}>R_{A}>R_{D}>R_{C}}\); that is, SBS content had the most obvious influence on the high-temperature stability of the modified rejuvenated asphalt. If only considering the thermal stability of the material, the optimal scheme was \(\rm{A_{3}B_{3}C_{1}D_{1}}\). The 5 \({}^{\circ}\)C ductility represents the low-temperature performance of asphalt. From the perspective of focusing on the low-temperature cracking resistance of asphalt products, the optimal preparation scheme was \(\rm{A_{2}B_{3}C_{1}D_{2}}\), and the optimal one based on the elastic recovery rate index was \(\rm{A_{2}B_{2}C_{1}D_{3}}\). According to the above results and analysis, SBS content was the most important factor affecting the performance of asphalt samples, followed by REOB content, which had the greatest influence on the index of penetration.