## 4 Conclusions  
In this paper, the influence of gradation on the stress absorption performance of AR-SAMI was studied. Based on the BBT, LT-SCB, CE-SCB, and OT tests, key sieve hole method, graded fractal method, and Bayley method parameters were used as indicators. The main conclusions are as follows:  
* The AR-SAMI with different gradations showed different performance in different tests, with a maximum difference of 56.07%. The AR-SAMI of 10B gradation had the best performance in the BBT, while the AR-SAMI of 10A and 10B gradation had the best performance in the LT-SCB test. The AR-SAMI of 10C gradation had the best performance in the CE-SCB test, and the AR-SAMI of 10B and 10C gradation had good performance in the OT.
* The different tests were influenced by different parameters. The performance of the AR-SAMI in the BBT improved with the increase of the \(P_{475\text{mm}}\) and \(P_{2,36\text{mm}}\), \(PCSI\), and \(D_{c}\). However, the performance of the AR-SAMI in the CE-SCB test deteriorated with the increase of these parameters. The performance of the AR-SAMI in the LT-SCB test improved with the increase of the asphalt film thickness, while the performance of the AR-SAMI in the OT worsened with the increase of the \(CA\).
* The stress absorption performance of asphalt mixtures consisted of two aspects: crack resistance and crack expansion resistance. These two aspects were inversely related to each other, meaning that a mixture with better crack resistance did not necessarily have better crack expansion resistance.  
* The \(-10\)\({}^{\circ}\)C BBT, LT-SCB, CE-SCB, and OT tests could be used to evaluate the stress absorption performance, but they reflected different aspects of performance. It was recommended to use the \(-10\)\({}^{\circ}\)C BBT and CE-SCB tests as the evaluation methods of stress absorption performance. The \(\varepsilon_{B}\) and \(D_{\infty}\) of the \(-10\)\({}^{\circ}\)C BBT and the \(G_{f}\) and \(FI\) of the CE-SCB test were recommended as the evaluation indicators.  
This paper evaluated the stress absorption performance of asphalt mixtures with different gradations, but the number of gradations was limited, and, thus, could not provide a comprehensive and effective comparison. Therefore, further research is needed to explore the influence of more gradations on stress absorption performance. In addition, this paper only focused on the effect of gradation on stress absorption, which was not sufficient to reflect the actual engineering performance of asphalt mixtures. It is recommended to combine the road performance of AR-SAMI with the stress absorption performance to obtain a more realistic and comprehensive evaluation.  
Conceptualization, P.L.; methodology, P.L.; validation, X.X.; formal analysis, X.X.; investigation, S.T.; resources, P.L.; data curation, J.L.; writing--original draft preparation, X.X.; writing--review and editing, W.P.; visualization, B.W.; supervision, S.L.; project administration, P.L.; funding acquisition, P.L. All authors have read and agreed to the published version of the manuscript.  
This research was funded by the National Key Research and Development Program of China, grant number 2021 YFB2601000, Guangxi Key Research and Development Program, grant number AB21220070, Guangxi Science and Technology Major Program, grant number 2023 AA14005, and Airport Engineering Research Center of CAAC Program, grant number ERCAOTP20220301.  
Not applicable.  
The authors declare no conflict of interest.