# Preparation and Properties of SBS/REOB-Modified Rejuvenated Asphalt
## 4 Results and Analysis
### Orthogonal Test
The shear time and shear rate mainly affected the elastic recovery performance of materials and had the least influence on the softening point index. Taking the shear time as an example, the softening point change value was only 0.13 \({}^{\circ}\)C when the horizontal change was made. Overall, in order to obtain high-temperature stability, low-temperature performance, elastic recovery performance, and the viscosity of modified rejuvenated asphalt, the optimal schemes were \(\rm{A_{2}B_{3}C_{1}D_{3}}\) and \(\rm{A_{3}B_{3}C_{1}D_{3}}\); that is, \"9% REOB, 4.5% SBS, and 5000 r/min for 40 min\" and \"7% REOB, 4.5% SBS, and 5000 r/min for 40 min\". The two schemes A2B3C1D3 and A3B3C1D3 had the advantage in low-temperature performance and high-temperature performance, respectively. Since this modified regenerative process was aimed at improving the low-temperature performance of REOB rejuvenated asphalt, the 4.5% SBS + 9% REOB ratio was selected for the subsequent test to prepare modified regenerative asphalt. \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Range Calculated Value**} & \multicolumn{5}{c}{**Experimental Factor**} \\ \cline{2-6}  & **A** & **B** & **C** & **D** & **Impact Priority** \\ \cline{2-6}  & **REOB Dosage** & **SBS Dosage** & **Shear Time** & **Shear Rate** & \\ \hline \multirow{3}{*}{Needle penetration/mm} & \(\overline{K_{i1}}\) & 76.00 & 79.73 & 74.83 & 75.27 & \\  & \(\overline{K_{i2}}\) & 72.93 & 78.43 & 73.73 & 73.87 & \\  & \(\overline{K_{i3}}\) & 72.90 & 63.67 & 73.27 & 72.70 & B \textgreater{} A \textgreater{} D \textgreater{} C \\  & \(\overline{K_{j}}\) & **4.10** & **16.06** & **1.56** & **2.57** & \\ \hline \multicolumn{2}{c}{The optimal level} & \(\bf{A_{3}}\) & \(\bf{B_{3}}\) & \(\bf{C_{3}}\) & \(\bf{D_{3}}\) & \\ \hline \multirow{3}{*}{Softening point/\({}^{\circ}\)C} & \(\overline{K_{j1}}\) & 59.87 & 57.50 & 60.83 & 61.07 & \\  & \(\overline{K_{i2}}\) & 61.17 & 61.87 & 60.70 & 60.67 & \\  & \(\overline{K_{i3}}\) & 61.27 & 62.93 & 60.77 & 60.57 & B \textgreater{} A \textgreater{} D \textgreater{} C \\  & \(\overline{K_{j}}\) & **1.40** & **5.43** & **0.13** & **0.50** & \\ \hline \multicolumn{2}{c}{The optimal level} & \(\bf{A_{3}}\) & \(\bf{B_{3}}\) & \(\bf{C_{1}}\) & \(\bf{D_{1}}\) & \\ \hline \multirow{3}{*}{\(5\)\({}^{\circ}\)C} & \(\overline{K_{i1}}\) & 26.13 & 25.07 & 27.97 & 27.80 & \\  & \(\overline{K_{i2}}\) & 29.03 & 27.40 & 27.40 & 28.07 & \\ \cline{1-1}  & \(\overline{K_{i3}}\) & 28.37 & 31.07 & 28.17 & 27.67 & B \textgreater{} A \textgreater{} C \textgreater{} D \\ \cline{1-1}  & \(\overline{K_{j}}\) & **2.90** & **6.00** & **0.77** & **0.40** & \\ \hline \multicolumn{2}{c}{The optimal level} & \(\bf{A_{2}}\) & \(\bf{B_{3}}\) & \(\bf{C_{1}}\) & \(\bf{D_{2}}\) & \\ \hline \multirow{3}{*}{Extension/\%} & \(\overline{K_{i1}}\) & 81.67 & 79.00 & 84.67 & 82.67 & \\  & \(\overline{K_{i2}}\) & 85.33 & 87.00 & 82.00 & 82.33 & \\ \cline{1-1}  & \(\overline{K_{i3}}\) & 82.00 & 83.00 & 82.33 & 84.00 & B \textgreater{} A \textgreater{} C \textgreater{} D \\ \cline{1-1}  & \(\bf{R_{j}}\) & **3.67** & **8.00** & **2.67** & **1.67** & \\ \cline{1-1}  & \(\bf{A_{2}}\) & \(\bf{B_{2}}\) & \(\bf{C_{1}}\) & \(\bf{D_{3}}\) & \\ \hline \multicolumn{2}{c}{Range mean} & \(\bf{3.02}\) & \(\bf{8.87}\) & \(\bf{1.29}\) & \(\bf{1.41}\) & B \textgreater{} A \textgreater{} D \textgreater{} C \\ \hline \hline \end{tabular}
\end{table} 
Table 9: Range calculation table.