## 3 Results  
### Rheological Properties  
#### 3.1.1 High-Temperature Rheological Properties  
FS tests were carried out at different frequencies by oscillatory shear strain. They revealed the effect of loading frequency on the viscoelastic properties of RAMB. Figure 5 lists the G\({}^{\star}\) and \(\delta\) values of six asphalts at different frequencies. The composite shear modulus, G\({}^{\star}\), characterizes the resistance value of the asphalt material during repeated deformation in shear. \(\delta\) represents the hysteresis of the stress relative to the stress. G\({}^{\star}\) and \(\delta\) together represent the viscoelastic properties of the asphalt: the larger the \(\delta\) value, the closer the asphalt is to a viscous body, while the smaller the \(\delta\) value, the closer the asphalt is to an elastomer, meaning the asphalt is more resistant to deformation at high temperatures. The G\({}^{\star}\) value of the six asphalts gradually increased and the \(\delta\) value decreased with the increase in frequency. Compared to matrix asphalt, the G\({}^{\star}\) value of bio-asphal was significantly reduced and the \(\delta\) value improved. The lack of high-temperature performance can be attributed to bio-oil containing lots of free fatty acids. Free fatty acids are introduced when bio-oil replaces part of the matrix asphalt. This is one of the reasons for the poor nutting resistance of bio-asphalt [31]. Compared to the G\({}^{\star}\) value and \(\delta\) values of untreated bio-asphalt, treated bio-asphalt, rock asphalt-modified bio-asphalt and montmorillonite-modified bio-asphalt, pretreatment, rock asphalt and montmorillonite improved the G\({}^{\star}\) value of bio-asphalt. The \(\delta\) value of bio-asphalt was also reduced. The modification effect of rock asphalt was most obvious. The G\({}^{\star}\) value of RAMB was greater than the matrix asphalt. The \(\delta\) value was lower than the matrix asphalt. Thus, pretreatment, rock asphalt and montmorillonite comprehensively increase the elastic component, the G\({}^{\star}\) value and the high-temperature nutting of bio-asphalt. G\({}^{\star}\) values are sorted as follows: RAMB > matrix asphalt > rock asphalt-modified bio-asphalt > montmorillonite-modified bio-asphalt > treated bio-asphalt > untreated bio-asphalt. Figure 5: Graph of the G\({}^{\star}\) and \(\delta\) values of six asphalts at 58 \({}^{\circ}\)C.  
MSCR  
The shear strain of the six asphalts is shown in Figure 6. The strain of asphalt under 0.1 KPa was small and the difference between different asphalts was also small. However, the strain of asphalt sharply increased under 3.2 KPa. The growth rate showed a significant difference. The untreated bio-asphalt exhibited a large deformation under the action of load. The shear strain increased rapidly with the repeated loading. The pretreatment and single modifier reduced the shear strain of bio-asphalt, but the effect was not as good as that of rock asphalt-montmorillonite materials composite-modified bio-asphalt. J\({}_{\text{nr}}\) can reflect the permanent deformation resistance of asphalt: the smaller the value, the higher the deformation resistance of the asphalt at high temperatures. R can represent the elastic component of the asphalt: the larger the value, the more elastic the asphalt. J\({}_{\text{nr}}\) and R values of six asphalts at 0.1 KPa and 3.2 KPa are shown in Figures 7 and 8. Shown here, bio-asphalt had the lowest R value and the highest J\({}_{\text{nr}}\) value among the six asphalts. Bio-asphalt had a large shear deformation under the action of stress. The plastic deformation was the main part, with only a small portion of elastic deformation. The R value of montmorillonite-modified bio-asphalt, treated bio-asphalt and untreated bio-asphalt became negative under 3.2 KPa because the high-temperature performance of the three kinds of asphalt at 58 \({}^{\circ}\)C was insufficient in the nonlinear viscoelastic range. The order of R values of the 6 groups of asphalt samples was RAMB > MA >RMB > MMB > TBA > UBA.