## 4 Revised Service Life Prediction Model Suggested by DuraCrete  
The performance evolution of a concrete structure with respect to reinforced corrosion and related events, from reinforced depassivation to construction collapse, is shown in Figure 11. During the first period, chloride ions penetrate into the concrete and induce the depassivation of the reinforced bar. This period is named the design service life of concrete in marine environments. Since there are fluctuations in the durability parameters of concrete, a reliability design is introduced into the durability design, and the design idea is shown in Figure 12. The probability of failure within the period [0, T] can be expressed by Equation (5), and the limit state function can be written as Equation (6). The service life prediction model of concrete in chloride environments, as suggested by DuraCrete, is shown as Equation (7). Figure 11: Events during a service life. Figure 10: Comparison between atmospheric temperature and concrete temperature. activation energy (\(q\) = 3739 K for PFA and \(q\) = 2776 K for OPC [35]), and \(T_{0}\) = 293 K (20 \({}^{\circ}\)C). Using Equation (10), the surface chloride ion concentration of the concrete can be calculated. The characteristic values of the regression parameter \(A_{C_{s,cl}}\) and critical chloride concentration \(C_{CR}\) for different types of concrete in different corrosion zones are shown in Tables 4 and 5, respectively. \[C_{s,cl}=A_{C_{s,cl}}\left(\frac{w}{b}\right)\gamma C_{s,cl} \tag{10}\]  
The chloride ion diffusion coefficient of concrete decreases with exposure time, and is inversely proportional to corrosion time [36; 37; 38; 39]. Further, the age factors of different types of concrete in different corrosion zones are shown in Table 6. It is worth mentioning that the chloride ion diffusion coefficient \(D_{RCM,0}\) decreases with time, and actually stabilizes gradually as time increases, to a certain degree. In this model, \(D_{RCM,0}\) is modified through the change in the age factor \(n_{cl}\), and \(D_{RCM,0}\) is obtained through a short-time RCM test. Hence, the age factor \(n_{cl}\) corresponds to the instantaneous chloride diffusion coefficient in this paper. Additionally, chloride ions' penetration into concrete is affected by the environment and the curing age [40]. The chloride diffusion coefficient can be expressed by Equations (11) and (12), and the characteristic values of the environment factor and the curing factor are shown in Tables 7 and 8. Further, the partial factors relevant for structures in a marine environment are shown in Table 9. \begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **OPC** & **PFA** & **GGBS** & **SF** \\ \hline
**Atmospheric** & 0.65 & 0.66 & 0.85 & 0.79 \\
**Tidal and Splash Zones** & 0.37 & 0.93 & 0.60 & 0.39 \\
**Submerged** & 0.30 & 0.69 & 0.71 & 0.62 \\ \hline \hline \end{tabular}
\end{table} 
Table 6: Age factor of the chloride diffusion coefficient \(n_{cl}\). \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **OPC** & **PFA** & **GGBS** & **SF** \\ \hline
**Atmospheric** & 2.57 & 4.42 & 3.05 & 3.23 \\
**Tidal and Splash** & 7.76 & 7.45 & 6.77 & 7.96 \\
**Submerged** & 10.3 & 10.8 & 5.06 & 12.5 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Characteristic values of the regression parameter \(A_{C_{s,cl}}\) (%, relative to binder). \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **OPC** & **PFA** & **GGBS** & **SF** \\ \hline
**Atmospheric** & 0.65 & 0.66 & 0.85 & 0.79 \\
**Tidal and Splash Zones** & 0.37 & 0.93 & 0.60 & 0.39 \\
**Submerged** & 0.30 & 0.69 & 0.71 & 0.62 \\ \hline \hline \end{tabular}
\end{table} 
Table 7: Characteristic values of the environment factor \(k_{e,cl}\). \begin{table}
\begin{tabular}{c c c c} \hline \hline  & **OPC** & **PFA** & **GGBS** & **SF** \\ \hline
**Atmospheric** & 2.57 & 4.42 & 3.05 & 3.23 \\
**Tidal and Splash** & 7.76 & 7.45 & 6.77 & 7.96 \\
**Submerged** & 10.3 & 10.8 & 5.06 & 12.5 \\ \hline \hline \end{tabular}
\end{table}