## 5 Anti-Rutting Analysis of HMAC Pavement under Continuous Temperature Variation
### Comparison of Putting Resistance between HMAC and Conventional Asphalt Pavement  
#### 5.3.1 Comparison of Permanent Deformation of Surface Layers  
In order to further analyze the rutting resistance performance of HMAC, the permanent deformation was simulated for both HMAC and conventional asphalt pavement. The material parameters of the middle surface layer in conventional asphalt pavement are shown in Table 14. The permanent deformations are shown in Table 15 and Figures 12-14.  
As shown in Figures 12 and 13, the internal deformation of conventional asphalt pavement changed with the increase of cumulative vehicle loading time, and its pattern variations were consistent with HMAC pavement. However, in the continuous temperature changing condition, the deformation curve of HMAC pavement fluctuated less with time and temperature, which was due to the low sensitivity of high modulus asphalt materials to temperature fluctuations. Therefore, the use of HMAC can reduce damage to the road surface caused by temperature changes.  
Under continuous loading, with increasing depth, the difference in vertical displacement between HMAC pavement and conventional asphalt pavement decreased. The internal deformation of the conventional asphalt pavement increased at a faster rate, resulting in a larger difference with the  
Figure 12: Comparison of vertical deformation at different depths underneath the center of the leftmost wheel.  
Figure 13: Comparison of vertical deformation at different depths underneath the dual-wheel center.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Pavement Type** & **Depth (cm)** & \begin{tabular}{c} **Deformation under** \\ **Point B (mm)** \\ \end{tabular} & \
\begin{tabular}{c} **Deformation under** \\ **Point A (mm)** \\ \end{tabular} &
\begin{tabular}{c} **Maximum Relative** \\ **Deformation (mm)** \\ \end{tabular} \\ \hline \multirow{3}{*}{HMAC Pavement} & 0 & \(-\)2.57 & 1.14 & 3.71 \\  & 4 & \(-\)1.84 & 0.35 & 2.19 \\  & 10 & \(-\)1.05 & \(-\)0.36 & 1.05 \\ \hline \multirow{3}{*}{Conventional Asphalt Pavement} & 0 & \(-\)6.25 & 4.59 & 10.84 \\  & 4 & \(-\)4.16 & 3.24 & 7.4 \\ \cline{1-1}  & 10 & \(-\)1.47 & 0.12 & 1.59 \\ \hline \hline \end{tabular}
\end{table}
Table 15: Material parameters of middle surface layer of conventional asphalt pavement.  
permanent deformation of the HMAC pavement, and the deformation value of both permanent tended to be stable after 4000 s.  
From Table 15 and Figure 14, it can be seen that the deformation values of the conventional asphalt pavement at different depths were much higher than those of the HMAC pavement. At the road surface, the maximum relative deformation of conventional asphalt pavement was 10.84 mm, which was 7.13 mm higher than that of HMAC, and the difference in deformation values was the largest. The second-highest difference in deformation was 5.21 mm at the bottom of the upper surface layer. At a depth of 10 cm, although the vertical deformation was small, the maximum relative deformation of the conventional asphalt pavement was 1.59 mm. This was an increase of 51.4%compared to the HMAC pavement. Therefore, the HMAC material can significantly reduce the permanent deformation of pavement.  
In the conventional asphalt pavement, the maximum relative deformation generated in the middle surface layer was the largest, at 5.81 mm. Therefore, the HMAC layer that was located in the middle surface layer could effectively reduce the relative deformation. Simultaneously, the deformation rate of the upper surface layer was also greatly reduced, thereby reducing the permanent deformation of the entire pavement.  
To summarize, the permanent deformation of the two pavement structures mainly occurred in the upper and middle surface layers, while the settlement of HMAC in middle surface layer could effectively decrease the permanent deformation.