## 6 Conclusions and Recommendations  
Based on a sizeable wet temperature cycle test and a mechanical performance test of each cutting layer, the following conclusions are drawn by analyzing the factors affecting the mechanical properties of the AC-13 asphalt mixture.  
1. With the increase in the number of sizeable wet temperature cycles, the shear strength, flexural-tensile strength and strength modulus of the asphalt mixture with different air voids (5.9%, 5.0%, 4.1%) and depths (Cut Layer 1-4) decay more and more severely. When the number of sizeable wet temperature cycles reaches 100, the flexural-tensile strength, strength modulus and shear strength decayed by 32.01%, 23.39%, and 22.30% at the maximum.
2. Under the action of the sizeable wet temperature cycle, the decay degree of the flexural-tensile strength, strength modulus, and shear strength first increases rapidly and then decreases with the increase in the number of sizeable wet temperature cycles; the decay degree of the shear strength increases rapidly in the first 50 cycles, and that of the flexural-tensile strength and strength modulus increases rapidly in the first 75 cycles, and later the decay of all the three gradually slows down in subsequent cycles.
3. Under the same conditions of a sizeable wet temperature cycle, the smaller the void ratio and the deeper the asphalt mixture, the smaller the decay degree of shear strength, flexural-tensile strength and strength modulus, and vice versa.  
4. The Grey correlation method was used to analyze the influencing factors of the mechanical property decay of the asphalt mixture under the action of the sizeable wet temperature cycle, the functional relationship between the influencing factors and strength modulus was established, and finally correction coefficients were introduced to optimize the integration of the established functional relationship. The results show that the importance of the influencing factors is in the following order: the number of sizeable wet temperature cycles > gap ratio > depth. The prediction equation can better predict the magnitude of the strength modulus regardless of void ratio, number of sizeable wet temperature cycles and depth, and the correlation between the predicted and actual values can be up to 0.925.  
The conclusions presented in this paper are based on selected road surface temperature and rainfall. It is recommended that performance tests of asphalt mixtures with different road surface temperatures and rainfall levels be performed to better understand their behavior. In addition, it is advisable to consider conducting sizeable wet temperature cycle simulations and performance tests on the upper, middle, and lower layers of the pavement structure.  
Study conception and design: Y.-L.L., J.-G.W. and Q.-L.F.; test: Y.-L.L. and L.-D.Z.; data collection and analysis: Y.-L.L. and F.L.; draft manuscript preparation: Y.-L.L.; review and editing: Y.-L.L. All authors have read and agreed to the published version of the manuscript.  
This work was funded by the Hunan Provincial Natural Science Foundation grant number 2022 JJ30594 and Changsha Natural Science Foundation grant number kq2014109.  
Not applicable.  
The data are included within this article.  
The authors declare no conflict of interest.