# Time-Dependency in the Corrosion Process of Reinforced Concrete Subjected to a Chloride Solution
## 5 Conclusions  
This study evaluated the chloride-induced corrosion of steel in concrete as part of a performance-based method for evaluating the durability of concrete structures. Laboratory-based experiments were performed using electrochemical techniques with concrete samples  
Figure 13: Example for estimation of time to corrosion initiation depending on electrochemical measurement.  
simulated in a marine structure. Consequently, the data from both techniques used in this study were proven to be comparable for estimating corrosion when possible error sources from the experimental conditions were excluded. In addition, the results confirmed that a simplified electrical equivalent circuit, rather than a complex one, is suitable for analysing the impedance data for EIS measurements. The following conclusions were drawn from the results of this study:  
(1) The corrosion potential from the HP measurements and the time constant from the GP technique are valuable corrosion indicators owing to their rapid response and simple measurement; however, they are only qualitative and thus, additional experiments or analyses are necessary for quantifying the corrosion rate.  
(2) The impedance response was confirmed to be more stable when using an internal counter electrode than when using an external counter electrode owing to the reduction in the experimental variables. Analysing the impedance data that are consistently sensitive to various variables is beneficial. Carbon steel, which is less resistant to corrosion, was used as the counter electrode, and its utility was confirmed.  
(3) The results obtained from the EIS measurements were analysed with a simple equivalent electrical circuit, and the ohmic and polarisation resistances from the EIS were compared with those from the GP technique. The difference in the calculated time for each technique was observed to estimate the time to the onset of corrosion. Moreover, the results confirmed the feasibility of the analysis methods.  
As previously discussed, EIS is an elaborate and sensitive technique for describing the corrosion process, whereas the GP technique is practical; therefore, this study demonstrated that the understanding of the corrosion process and the accuracy of the corrosion rate can be improved by enhancing the compatibility of both techniques. However, these techniques have the following limitations for elaborate applications: (1) quantification of the polarised area [41]; (2) quantification of impedance related to the diffusion process [42]; (3) sensitivity of measurements, such as the geometry factor [43]. Further studies are necessary under the aforementioned conditions.  
Conceptualization, methodology, validation, formal analysis, J.K.; investigation, resources, data curation, S.P.; writing--original draft preparation, S.P.; writing--review and editing, J.K.; visualization, S.P.; supervision, J.K.; project administration, D.-W.S.; funding acquisition, D.-W.S. All authors have read and agreed to the published version of the manuscript.  
This study was supported by a Ministry of Science and ICT (MSIT) grant from the Korea Institute of Civil Engineering and Building Technology (KICT). (Project Number: KICT-20230107, Development of Specialized and Localized Road Bridge Technology for the Growth of Infrastructure in New Southern Countries).  
Not applicable.  
The data presented in this study are available on request from the corresponding author. The data are not publicly available due to privacy and ethical restrictions.  
The authors declare no conflict of interest.