# Silane Modification of Crumb Rubber on the Rheological Properties of Rubberized Asphalt
## 3. Experimental Result and Discussion  
### High Temperature Stability  
The high temperature stability performance of asphalt mainly shows that it still has the ability to resist permanent deformation under the repeated shear at high temperatures, and the change of viscoelastic composition is relatively stable [18; 19]. The following content will be analyzed from the complex modulus and damping factor of asphalt and their changing trends are displayed in Figure 1 and Table 4.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c} \hline \hline  & \multicolumn{3}{c}{**AM**} & \multicolumn{3}{c}{**AR**} & \multicolumn{3}{c}{**MAR**} \\ \hline
**Temp (\({}^{\circ}\)C)** & \(G^{\star}\)**(kPa)** & \(\delta\) (\({}^{\circ}\)) & **tan (\(\delta\))** & **Temp (\({}^{\circ}\)C)** & \(G^{\star}\)**(kPa)** & \(\delta\) (\({}^{\circ}\)) & **tan (\(\delta\))** & **Temp (\({}^{\circ}\)C)** & \(G^{\star}\)**(kPa)** & \(\delta\) (\({}^{\circ}\)) & **tan (\(\delta\))** \\ \hline
50.2 & 7.02 & 85.12 & 11.7 & 50.6 & 36.8 & 57.99 & 1.6 & 50 & 46.1 & 55.59 & 1.46 \\ \hline
50.3 & 6.19 & 85.53 & 12.8 & 51.3 & 34 & 58.78 & 1.65 & 50.5 & 44.2 & 55.95 & 1.48 \\ \hline
50.7 & 5.17 & 85.92 & 14 & 52 & 31.3 & 59.53 & 1.7 & 51.1 & 41.1 & 56.48 & 1.51 \\ \hline
51.5 & 4.22 & 86.29 & 15.4 & 52.8 & 28.7 & 60.39 & 1.76 & 52 & 37.4 & 57.17 & 1.55 \\ \hline
52.3 & 3.6 & 86.55 & 16.6 & 53.6 & 26.3 & 61.21 & 1.82 & 53 & 33.4 & 57.99 & 1.6 \\ \hline
53.3 & 3.04 & 86.82 & 18 & 54.5 & 24 & 61.99 & 1.88 & 54.1 & 29.6 & 58.78 & 1.65 \\ \hline
54.2 & 2.58 & 87.07 & 19.5 & 55.3 & 21.8 & 62.85 & 1.95 & 54.9 & 27.1 & 59.39 & 1.69 \\ \hline
55 & 2.23 & 87.28 & 21 & 56.2 & 19.8 & 63.66 & 2.02 & 55.6 & 24.9 & 59.97 & 1.73 \\ \hline
56 & 1.95 & 87.46 & 22.5 & 57.1 & 17.9 & 64.54 & 2.1 & 56.4 & 22.7 & 60.67 & 1.78 \\ \hline
57 & 1.71 & 87.64 & 24.2 & 58 & 16.1 & 65.46 & 2.19 & 57.3 & 20.7 & 61.35 & 1.83 \\ \hline
58 & 1.51 & 87.78 & 25.8 & 59 & 14.5 & 66.41 & 2.29 & 58.1 & 18.9 & 61.99 & 1.88 \\ \hline
59.1 & 1.34 & 87.93 & 27.6 & 60 & 13 & 67.30 & 2.39 & 59 & 17.1 & 62.73 & 1.94 \\ \hline
60.2 & 1.19 & 88.05 & 29.3 & 61 & 11.6 & 68.20 & 2.5 & 60.1 & 15.1 & 63.55 & 2.01 \\ \hline
61.3 & 1.06 & 88.17 & 31.3 & 61.9 & 10.4 & 69.11 & 2.62 & 61.4 & 13.1 & 64.4 Figure 1: DSR temperature scanning test results, where (**a**) shows complex modulus, and (**b**) shows phase angle, and (**c**) shows damping factor. Figure 1a shows clearly that the complex moduli of AR and MAR were higher than those of AM with increasing temperature, and AM had the lowest complex modulus and both AR and MAR had a higher complex modulus with a similar declining trend. Because CR and MCR absorb most lightweight components, such as oil and resin, within asphalt during the rubber swelling process, the relative content of heavy components, like asphaltene, increases. In addition, due to organic functional groups of the silane coupling agent grafting on the rubber surface, MCR could absorb more oil and resin, which results in a higher complex modulus [20]. Under these circumstances, since a stronger interface has been formed between MCR and asphalt, adhesion and bonding state are enhanced as a result of the chemical effects [9] and asphalt still has a higher consistency and a better ability to resist deformation. Therefore, the ability of MAR to resist repeated shearing stress is enhanced by KH-550. However, the complex moduli of all samples decreased with increasing temperature, which means anti-shearing stress ability was gradually weakening. Figure 1b shows the change in the phase angle of the asphalt sample with temperature. It is obvious that AM had the largest phase angle while MAR had the lowest phase angle. When the phase angle was converted to tan (\(\delta\)), this change in viscoelastic part within asphalt was more violent and moderate for AM and rubberized asphalt. Figure 1c shows the damping factor changing trends of AM, AR, and MAR.