# Probability-Based Concrete Carbonation Prediction Using On-Site Data
## 5 Application Examples
### Durability Analysis of Carbonated Concrete Structures  
Based on the results of the sensitivity analysis, nine samples for LHS were applied in the proposed durability analysis and the first two field inspection data were then used to revise prior predicted values for carbonation depth of the subject bridges. To compare the effectiveness of the proposed durability analysis, two carbonation prediction models were compared in this study. In the previous studies, [PERSON] et al. and [PERSON] have compared several carbonation prediction models and reported that the Kishitani prediction model was suitable for the concrete structures in Korea [11,32]. Moreover, [PERSON] et al. investigated various field inspection data of carbonation in Korea and proposed the correction factors to revise previous prediction models [33]. Thus, the proposed prediction approach compared with the Kishitani model and the [PERSON] et al. model is illustrated in Figure 7. The figures show that the updated posterior results are more suitable for predicting carbonation depth with time.  
Carbonation reliability indices according to elapsed years from prior prediction and posterior prediction have been calculated for the subject bridges. Figure 8 shows reliability indices for the Gajwa IC viaduct and the Geoje bridge. As described earlier, each bridge has different environmental and design conditions, and the inspection data for predicting reliability indices are also used for different parts of the bridge (Gajwa IC viaduct: pier, Geoje bridge: girder). Thus, the reliability index of the Gajwa IC viaduct was higher than that of the Geoje bridge in this analysis.  
The reliability index for effective management in the field is hard to standardize in the field because of various conditions such as environment, design, materials, etc. In this analysis, the structural damage was assumed to occur at reliability indices of 1.5 and 0.7 for the Gajwa IC viaduct and Geoje bridge, respectively.  
Damage in the Gajwa IC viaduct was initially estimated to occur in 57 years, and its remaining service life was then increased to 77 years after considering field inspection data. Furthermore, damage to the Geoje bridge was initially predicted to occur in 68 years, but its remaining service life was then  
Figure 7: Changes in prior and posterior predicted values for carbonation depth of the subject bridge.  
(a) Gajwa IC viaduct; (b) Noryang bridge; (c) Geoje bridge.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Design Variables** & **Prior Values (Mean, Standard Deviation)** \\ \hline \(D_{CO_{2}}\) (\(\times 10^{-4}\) cm\({}^{2}\)/s) & \(N(3.87,3.79)\) \\ \hline \(C_{CO_{2}}\) (g/cm\({}^{3}\)) & Using Equation (4), (0.74) \\ \hline \(a\) (g/cm\({}^{3}\)) & Using Equation (5) and Table 1, (1.65) \\ \hline \(a_{H}\) & Using Equations (6) and (7), (0.12) \\ \hline \hline \end{tabular}
\end{table}
Table 5: Mean and standard deviation according to design variables.  
critically reduced to 37 years after updating. Therefore, it is recommended to intensively monitor and manage the deterioration of superstructures in the Geoje bridge.