## 3 Experimental Plan
### Exposure Conditions  
At the end of the curing period, samples were taken out of the chamber and stored under laboratory conditions (23 \(\pm\) 2 \({}^{\circ}\)C and 60% RH). One of the two columns without chloride-contaminated concrete underwent an accelerated carbonation process (column C), and the column was partially carbonated (150 mm LZ, which corresponded to the zone of that manufactured with lower quality concrete). For this purpose, casing was prepared on the first 150 mm of the column with PVC tubing (\(\mathcal{O}\)180 mm), which was sealed at the perimeter of the zone that was to be contaminated. Into this space, CO\({}_{2}\) was injected at a constant pressure of 1 atm. Based on the phenolphthalein tests and the weight control carried out on the auxiliary samples left in the casing (cylindrical specimens \(\mathcal{O}\)150 mm and 100 mm high), it took 31 days to completely carbonate 35 mm (more than the concrete cover, 20 mm). Figure 3 shows the pictures of the carbonation process that was carried out and the employed system.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline  & **Test** & **Scetimes 1** & **Geometry** & **Standard** & **Results 2** \\ \hline Compressive strength (f\({}_{\text{c}}\)) & 3 & \(\mathcal{O}\)100 \(\times\) 200 mm & UNE-EN 12390-3:2020 [58] & **0.8**: 18.98 MPa **0.5**: 40.50 MPa \\ \hline Absorption coefficient & 3 & \(\mathcal{O}\)100 \(\times\) 50 mm & & **0.8**: 8.38 \% **0.5**: 7.49 \% \\ \hline Porosity accessible to water & 3 & \(\mathcal{O}\)100 \(\times\) 50 mm & & **0.8**: 18.24 \% **0.5**: 16.42 \% \\ \hline Penetration of water under pressure (Z) & 4 & \(\mathcal{O}\)150 \(\times\) 150 mm & UNE-EN 12390-8: 2020 [60] & **0.8**: 103 mm **0.5**: 18 mm \\ \hline Gas permeability (K\({}_{\text{gas}}\)) & 3 & \(\mathcal{O}\)150 \(\times\) 50 mm & UNE 83981:2008 [61] & **0.8**: 433.15 \(\times\) 10\({}^{-18}\) m\({}^{2}\) **0.5**: 50.37 \(\times\) 10\({}^{-18}\) m\({}^{2}\) \\ \hline Non-steady-state migration coefficient (D\({}_{\text{nssm}}\)) & 3 & \(\mathcal{O}\)100 \(\times\) 50 mm & UNE-EN 12390-18:2021 [62] & **0.8**: 50.04 \(\times\) 10\({}^{-12}\) m\({}^{2}\)/s **0.5**: 25.35 \(\times\) 10\({}^{-12}\) m\({}^{2}\)/s **0.5**: 195.69 \(\Omega\)m \\ \hline \hline \end{tabular} \({}^{1}\) Test specimens per concrete type. 2 Results of the concretes with a water/cement ratio of 0.8 or 0.5.  
\end{table}
Table 2: Concrete characterisation.  
In this way, three columns under different conditions were used in this study:  
* Column A, where the part's LZ was free of the aggressive agents that could generate rebar depassivation;
* Column B, where the part's LZ was affected by the presence of the chlorides introduced during mixing (LZ);
* Column C, where the LZ underwent an accelerated carbonation process.  
The UZ of the three columns was free of aggressive agents and made from higher quality concrete (w/c ratio of 0.5) than that of the LZ (w/c ratio of 0.8).  
After curing and preparing samples, the three columns underwent a corrosion monitoring process on the 6 sensors embedded in each part (3 in the LZ and the other 3 in the UZ). This monitoring period lasted 4 months. During this period, the LZ of each column was periodically wetted with tap water, while the rest of the column remained areeated.