# Preparation and Properties of SBS/REOB-Modified Rejuvenated Asphalt
## 4 Results and Analysis
### Microscopic Test  
In order to study the dispersion of the modifiers and regenerators in the modified and rejuvenated asphalt, fluorescence images of the 4.5%SBS + 9% REOB were collected by fluorescence microscope and compared with the 4.5%SBS-modified asphalt. The fluorescence microscopic image is shown in Figure 7. The matrix asphalt will not have a fluorescence reaction, so the black area is the asphalt phase, and the green fluorescent part is the SBS phase. We used letters to describe the distribution of the modifier under the fluorescence microscope. The meanings of each letter are shown in Table 11. The particle size, distribution status, and letter representation combination of each asphalt are shown in Figure 7.  
SBS can undergo a physical swelling reaction with the light component of REOB rejuvenated asphalt under the action of high-speed shear, changing from a granular to a network structure. From the microscopic results, compared with Figure 7b,c,e, insufficient shear rate and shear time will lead to uneven dispersion of the SBS modifier and a poor modification effect. Some SBS particles were striated; in particular, when the shear rate was small, the SBS particles had the worst dispersion effect. The Figure 7d SBS-modified new asphalt and the Figure 7e modified rejuvenated asphalt prepared in the laboratory both showed B: a continuous asphalt phase, and the microstructure of the two was similar. SBS was suspended uniformly in the asphalt phase and formed a network structure with asphalt. The SBS phase in the modified rejuvenated asphalt basically reached the level of the modified asphalt. In terms of performance and structure, there was little difference between the 4.5% SBS + 9% REOB and the SBS-modified new asphalt under a reasonable process; that is, the feasibility and effectiveness of the modification regeneration process was demonstrated from both macro and micro perspectives [16].  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multicolumn{2}{c}{**Test Temperature**} & \multicolumn{2}{c}{\(-\)**12 \({}^{\circ}\)C**} & \multicolumn{2}{c}{\(-\)**18 \({}^{\circ}\)C**} & \multicolumn{2}{c}{\(-\)**24 \({}^{\circ}\)C**} \\ \hline \multirow{4}{*}{**Indicators**} & \multicolumn{2}{c}{**Stiffness**} & \multirow{2}{*}{**Creep**} & \multirow{2}{*}{**S/**} & \multirow{2}{*}{**m**} & \multirow{2}{*}{**S/**} & \multirow{2}{*}{**m**} \\  & **Modulus** & & & & & & \\  & **S/MPa** & & & & & \\ \hline \multirow{3}{*}{1} & 70\# base asphalt & 186.5 & 0.359 & 467.4 & 0.264 & 679.7 & 0.201 \\  & 9\% REOB+ aged asphalt & 323.8 & 0.314 & 506.3 & 0.253 & 748.6 & 0.190 \\  & 4.5\% SBS + 7\% REOB + aged asphalt & 40.5 & 0.447 & 139.6 & 0.361 & 299.5 & 0.289 \\  & 4.5\% SBS + 9\% REOB + aged asphalt & 39.9 & 0.447 & 121.0 & 0.348 & 288.6 & 0.304 \\  & 4.5\% SBS + 11\% REOB+ aged asphalt & 67.1 & 0.436 & 184.2 & 0.336 & 373.6 & 0.277 \\  & 3.5\% SBS + 9\% REOB + aged asphalt & 115.6 & 0.399 & 326.5 & 0.320 & 489.0 & 0.253 \\  & 4\% SBS + 9\% REOB + aged asphalt & 77.3 & 0.386 & 215.6 & 0.328 & 397.8 & 0.264 \\ \hline \hline \end{tabular}
\end{table}
Table 10: BBR bending creep test results of PAV aged asphalt.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**Describe** & **The Letter** & **Meaning** \\ \hline \multirow{3}{*}{Continuous phase} & P & Continuous polymer phase \\  & B & Continuous bituminous phase \\  & X & Both phases are continuous \\ \hline \multirow{2}{*}{Phase} & H & Uniform \\  & I & Uneven \\ \hline \multirow{3}{*}{Size} & S & Small \\  & M & Medium \\  & L & Large \\ \hline \multirow{3}{*}{Shape} & r & Circular \\  & s & Stripe \\ \cline{1-1}  & o & Other \\ \hline \end{tabular}
\end{table}
Table 11: Fluorescence microstructure meaning represented by each letter.