## 4 Conclusions  
The present study successfully characterized the passivation process of steel reinforcements in concrete using electrochemical methods. The results indicate that the passivation behavior of steel reinforcements in concrete is significantly influenced by the environment on the steel surface and the soaking time. Figure 8: The variation law of the corrosion current density during the passivation process of steel reinforcements in concrete. 1. As the soaking test time increased, the OCP gradually increased and stabilized after 5 days, indicating that the steel electrode transitioned from an active state to a passive state in the simulated liquid environment of concrete. The steel reinforcement developed a protective passive film that reduced its tendency to corrode. 2. After soaking for one day, the steel electrode showed significant early passivation, indicated by an increase in arc diameter. The EIS arc of the WE gradually increased in the first 5 days of soaking, suggesting dynamic passive film formation and development. Beyond 5 days, the passive film stabilized with minimal further changes in its impedance spectrum, indicating carbon steel electrode passivation. 3. The working electrode's impedance increased significantly on the fifth day and gradually increased slightly after 10 days, indicating comprehensive coverage by the oxide film. Attributed to the growth and development of the oxide film, the electrode resistance reached a relatively stable state after the fifth day. 4. The shift in corrosion potential offers an indication of the level of passivation of steel reinforcements. The decrease in the anode Tafel slope and increase in the corrosion potential indicate the formation and stabilization of an oxide film on the steel surface, which is beneficial for its long-term durability in concrete structures. In conclusion, the present study provided a comprehensive understanding of the passivation process of steel reinforcements in concrete. By analyzing the OCP, EIS, and dynamic potential polarization curve method data, it is possible to gain insights into the passivation behavior of steel reinforcements in concrete structures, which provides a basis for optimizing the corrosion protection of steel reinforcements in concrete structures. However, further research under dangerous conditions, including different pH values as well as the influence of ions that break the passive state, is needed to optimize the passivation process. The composition of the corrosion products as a result of their interaction with the environment should be analyzed, and corrosion-resistant materials suitable for concrete should be developed accordingly, which would enhance its long-term stability under various environmental conditions. Conceptualization, D.L., H.L. ([PERSON]) and W.W.; methodology, D.L., Q.M. and W.W.; validation, H.L. ([PERSON]), G.T., C.S. and H.L. ([PERSON]); formal analysis, D.L., Q.M., W.W. and G.T. ; investigation, D.L., Q.M., C.S. and H.L. ([PERSON]); writing--original draft preparation, D.L., Q.M. and W.W.; writing--review and editing, H.L. ([PERSON]), G.T., C.S. and H.L. ([PERSON]); project administration, W.W. and G.T. ; funding acquisition, W.W. and G.T. All authors have read and agreed to the published version of the manuscript. This research was funded by the National Natural Science Foundation of China (grant number: 52208438), the Transportation Innovation and Development Technology Support Project of Jilin Province (grant number: 2023-1-5), the Transportation Key Technology Project of Jilin Province (grant number: 2023 ZDGC-1-3), the Scientific Research Project of the Department of Education of Jilin Province (grant number: JJKH20241300 KJ), the Natural Science Foundation of Jilin Province, the Fundamental Research Funds for the Central Universities, the Talent Development Special Fund Support Project of Jilin Province, and the Postdoctoral Researcher Selection Funding Project of Jilin Province. Not applicable.