## 3 Results
### Anti-Aging Performance
#### 3.2.2 Anti-Aging Performance of RAMB Based on Low-Temperature Rheological Performance  
The low-temperature bending beam tests of unaged and aged asphalt were carried out to compare the changes in S and m values. The S value of each asphalt increased after the aging treatment of the original asphalt, as shown in Figure 13. The polymerization reaction occurred inside the asphalt under the influence of aging and the low-molecular weight aromatic phenol was polymerized into high-molecular weight asphaltene. The aging of the asphalt made it physically brittle. Therefore, the aging was more damaging than it was for the original asphalt at low temperature. The m of long-term aging asphalt was greater than that of short-term aging asphalt, while the m of short-term aging asphalt was greater than that of original asphalt. The decrease in the rate of m was accelerated with the increase in aging. On the other hand, the S value of matrix asphalt after short-term aging exceeded 300 MPa and the m value was less than 0.3. The S and m value of rock asphalt-modified bio-asphalt and RAMB after short-term aging met the requirements. This shows that the  
Figure 10: Putting indexes of six asphalts. According to Equations (6) and (7), the SAI and mAI were calculated. When SAI is small and mAI is large, that asphalt has strong low-temperature aging resistance. The calculation results of the SAI and mAI are illustrated in Figures 14 and 15. According to Figures 14 and 15, the SAI value of untreated bio-asphalt was the largest among the six asphalts and the mAI value was the smallest. This shows that the deterioration of low-temperature properties was the most serious under the influence of aging. The SAI value was reduced and the mAI value was increased after distilled water treatment. The SAI value of rock asphalt-modified bio-asphalt, montmorillonite-modified bio-asphalt and matrix asphalt showed less differentiation. The anti-aging performance of bio-asphalt was only slightly improved by the addition of rock asphalt. The improvement effect of montmorillonite was obvious, but was not as pronounced as the matrix asphalt. Compared to the matrix asphalt, the SAI value of RAMB was smaller and the mAI value was larger. The SAI value of RAMB after short-term aging was 0.98 times that of matrix asphalt and the SAI value after long-term aging was 0.96 times that of matrix asphalt, while the mAI value after short-term aging was 1.03 times that of matrix asphalt and the mAI value after long-term aging was 1.01 times that of matrix asphalt. RAMB has good anti-aging performance. \[\text{SAI}=\frac{\text{Stiffness modulus of short or long term aging asphalt}}{\text{Stiffness modulus of original asphalt}} \tag{6}\]  
\[\text{mAI}=\frac{\text{Creep rate of short or long term aging asphalt}}{\text{Creep rate of original asphalt}} \tag{7}\]in asphalt. The peak intensity of two bio-oils were observed at 2923.88 cm\({}^{-1}\), 2853.37 cm\({}^{-1}\), 1743.18 cm\({}^{-1}\), 1463.41 cm\({}^{-1}\), 1377.09 cm\({}^{-1}\), 1162.01 cm\({}^{-1}\) and 967.08 cm\({}^{-1}\). The peak intensity of treated bio-oils was smaller than that of untreated bio-oils [32]. The peak corresponding to 967.08 cm\({}^{-1}\) is out-of-plane deformation of C-H bond. The peak corresponding to 1162.01 cm\({}^{-1}\) is stretching vibration of ester group O=C-O. The peak corresponding to 1377.09 cm\({}^{-1}\) is in-plane bending vibration of methyl C-H bond. The peak corresponding to 1463.41 cm\({}^{-1}\) is the in-plane bending vibration of methyl and methylene C-H. The peak corresponding to 1743.18 cm\({}^{-1}\) is the stretching vibration of ester O=C=O. The peak corresponding to 2923.88 cm\({}^{-1}\) is the stretching vibration of methylene CH\({}_{2}\). The peak corresponding to 2853.37 cm\({}^{-1}\) is stretching vibration of methyl CH\({}_{3}\)[33]. The peaks corresponding to 1162 cm\({}^{-1}\) and 1743 cm\({}^{-1}\) indicate that the bio-oil contained ester compounds [16; 34]. Ester compounds are volatile substances with low boiling points and strong volatility when heated.