# Design of SBS-Modified Bitumen Stabilizer Powder Based on the Vulcanization Mechanism
## 5 Optimization Design of the Stabilizer Component
### Carbon-White Content  
SBS bitumen was prepared according to the experimental design above, and the content of the stabilizer was 0.09% (expressed as S content). No gelation phenomenon occurred during the preparation process, and the 48-h segregation softening point difference test was carried out. The test results are shown in Figure 10.  
As can be seen from Figure 10, the 48-h segregation softening point difference of SBS-modified bitumen decreased about 2 \({}^{\circ}\)C with the incorporation of carbon-white, but there was no significant difference after the content of carbon-white exceeded 625%, so from the perspective of improving the thermal storage stability of bitumen, the content of carbon-white (relative to S) was 625%.  
\begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multirow{2}{*}{**Component No.**} & \multicolumn{4}{c}{**RTFOT**} & \multirow{2}{*}{**Penetration,**} \\  & **Loss on** & **Penetration** & **Residue Ductility at** & **0.1 mm, 25 \({}^{\circ}\)C** & **Index PI** \\  & **Heating, \%** & **Percentage, \%** & 5 \({}^{\circ}\)C & & \\ \hline
4 & 0.08 & 79.2 & 21.0 & 55.3 & 0.1 \\
25 & 0.11 & 77.2 & 18.9 & 54.4 & 0.1 \\
26 & 0.11 & 77.9 & 18.8 & 54.3 & 0.1 \\
27 & 0.11 & 78.5 & 18.4 & 54.5 & 0.1 \\
28 & 0.10 & 78.7 & 17.5 & 54.1 & 0.1 \\ \hline
**Component No.** & **Ductility at** 5 \({}^{\circ}\)C, cm** & **Softening Point \({}^{\circ}\)C** & **Brookfield viscosity at 135 \({}^{\circ}\)C, Pa-S** & **Solubility, \%** & **Resilient at** 25 \({}^{\circ}\)C, \%** \\ \hline
4 & 29.6 & 78.4 & 1.972 & 99.3 & 87.7 \\
25 & 29.5 & 79.7 & 1.984 & 99.4 & 87.4 \\
26 & 28.7 & 80.5 & 2.046 & 99.3 & 86.7 \\
27 & 27.8 & 81.5 & 2.107 & 99.2 & 87.3 \\
28 & 26.6 & 81.3 & 2.157 & 98.9 & 86.4 \\ \hline \hline \end{tabular}
\end{table}
Table 7: Performance of SBS-modified bitumen with different kaolin content.  
Figure 10: The relationship between carbon-white content and 48-h segregation softening point difference of SBS-modified bitumen.  
Table 8 shows the performance of SBS-modified bitumen with different carbon-white content.  
As can be seen from Table 8 above, the incorporation of carbon-white improves the softening point, the Brookfield viscosity at 135 \({}^{\circ}\)C and the penetration percentage after RTFOT. However, the enhancement was not significant in the experimental range; the improvement of the modified bitumen properties above was limited; with the increase of carbon-white content, the ductility after RTFOT decreased slightly; and the ductility at 5 \({}^{\circ}\)C decreases obviously. From the perspective of low temperature performance, the carbon-white content should be controlled.  
\"Technical Specification of Construction of Highway Asphalt Pavement (JTG F40-2004, China)\" regulates that the 48-h segregation softening point difference should be no more than 2 \({}^{\circ}\)C; according to the testing data, when the content of carbon-white was up to 625%, the 48-h segregation softening point difference of SBS-modified bitumen was less than 2 \({}^{\circ}\)C. Based on the economic factors and the technical performance of SBS-modified bitumen, especially the response to heat storage stability, it was suggested that the proper content of carbon-white (relative to S) be 625%.  
In conclusion, the components of SBS-modified bitumen stabilizer powder were S:TMTD:ZnO:BHT: Al\({}_{2}\)O\({}_{3}\):2 SiO\({}_{2}\):2H\({}_{2}\)O = 60:16:4:20:1250 or S:TMTD:ZnO:BHT:SiO\({}_{2}\) = 60:16:4:20:625, and SBS-modified bitumen has good performance, especially for the thermal storage stability.