## 3 Results and Discussion
### Pavement Performance Analysis
The low-temperature crack resistance values (\(\epsilon_{\rm B}\) and \(\rm{d}W/\rm{d}V\)) of AR were 26.6% and 38.1% higher, respectively, than those of the SBS bituminous mixture. According to the water stability results of the five bituminous mixtures in Figure 3, their freeze-thaw splitting tensile strength ratio was ranked as follows: AR > SBS > 70\({}^{\#}\)+M > 70\({}^{\#}\) > 70\({}^{\#}\)+PR. It can be seen that the freeze-thaw splitting strength ratio of the different bituminous mixtures had a slight difference. The _TSR_ value of the optimal AR bituminous mixture was 2.9% higher than the SBS bituminous mixture and 23.8% higher than the (70\({}^{\#}\)+PR) bituminous mixture. For the \(MS_{0}\) index, the ranking of these five bituminous mixtures was AR > 70\({}^{\#}\)+M > SBS > 70\({}^{\#}\) > 70\({}^{\#}\)+PR, so the AR bituminous mixture was also the best. In addition, the fatigue resistance of bituminous mixtures was also tested, and the ranking of fatigue resistance (\(N\!/\!\!/\)) is shown in Figure 4, i.e., SBS > AR > 70\({}^{\#}\)+PR > 70\({}^{\#}\) > 70\({}^{\#}\)+M. Therefore, the SBS bituminous mixture was the best, and its fatigue resistance was 29.1% higher than the AR bituminous mixture and 146.1% higher than that of the (70\({}^{\#}\)+M) bituminous mixture. For the economy evaluation, the cost order of these five bituminous mixtures is shown in Figure 3 and was as follows: 70\({}^{\#}\) > AR > SBS > 70\({}^{\#}\)+M > 70\({}^{\#}\)+PR. There was no significant difference among the five different bituminous mixtures. The cost of the 70\({}^{\#}\) bituminous mixture was 15.0% lower than that of the AR bituminous mixture and 39.7% lower than that of the (70\({}^{\#}\)+PR) bituminous mixture. The results in Table 7 and Figure 4 show that, after using different modification methods, the pavement performances of these bituminous mixtures were quite different. In addition, considering the different costs of the bituminous mixtures, it is impossible to select the modification method for a bituminous mixture with optimal comprehensive performance through simple comparison methods such as the equipartition and weighted evaluation methods. According to Figure 5, the first factor set was the set of desirable factors, \(U=\{\text{high-temperature stability},\text{low-temperature crack resistance},\text{water stability},\text{ fatigue resistance},\text{economy}\}\), in which \(U_{1}=\{DS,\,\varepsilon_{\text{r}}\},\,U_{2}=\{\varepsilon_{\text{B}},\, \text{d}W/\text{d}V\},\,U_{3}=\{TSR,\,MS_{0}\},\,U_{4}=\{N\},\)\(U_{5}=\{\text{Cost}\}\). The comment set was \(V=\{\text{SBS},\,\text{AR},\,70^{\text{th}}+\text{M},\,70^{\text{th}}+\text{PR}\}\). \(R_{i}\) (\(i=1,\,2,\,\ldots,\,n\)) was the subordination relationship of each influencing factor for the evaluation criterion. The membership function of each factor was positively processed; that is, the larger the membership degree, the more favorable it was. Moreover, the membership function was constructed. The greater the value, the better the technical index: \(r_{ij}=y_{ij}/\max(y_{ij})\); and the smaller the value, the better the technical index: \(r_{ij}=1-\left(y_{ij}-\min\left(y_{ij}\right)\right)/\max(y_{ij})\). According to the membership function, the membership degrees for four modified bituminous mixtures were calculated and they are listed in Table 8. The comprehensive evaluation matrix (\(R_{i}\)) was obtained by Equation (7). 2.2 Weight Analysis of Fuzzy Comprehensive Evaluation Model Based on Analytic Hierarchy Process and EW Methods  
The eigenvector of the weight of the C-level impact factor corresponding to the B-level impact factor was determined. For the high-temperature stability, low-temperature crack resistance, water stability, fatigue resistance and economy, the corresponding weight values were set as: \(w_{b1}=\{DS,\,\varepsilon_{\text{r}}\}=\{0.3,0.7\},\,w_{b2}=\{\varepsilon_{ \text{B}},\,\text{d}W/\text{d}V\}=\{0.3,0.7\},\,w_{b3}=\{TSR,\,MS_{0}\}=\{0.7,0.3\},\)\(w_{b4}=\{N\}=1,\,w_{b5}=\{\text{Cost}\}=1\).