## 2 Materials and Methods
### Rebar Corrosion Resistance Accelerated Test  
Three samples were casted for each concrete type (C and C*). The reinforced concrete specimens had dimensions of 180 mm \(\times\) 180 mm \(\times\) 80 mm with an embedded 12 mm diameter corrugated steel rebar located at 20 mm (cover depth from surface), see Figure 1. The ends of the steel rebars were sealed with insulating tape in order to obtain an exposed to corrosion rebar length of 14 cm. The test specimens were cured in the humid chamber (90% RH and 23 \({}^{\circ}\)C) over 75 days. After curing, a PVC pool was attached to the top of each specimen in order to allow ponding with water and a NaCl solution, as shown in Figure 1.  
It is known that it may take long to start the corrosion of steel bars embedded in concrete [1; 2; 3; 4]. For this reason, it was decided to perform an accelerated corrosion test based on wetting-drying cycles coupled with the periodic surface application of a certain amount of a 0.5 M NaCl aqueous solution in order to emulate environmental conditions similar to those that may be found in the marine tidal and splash exposure classes of marine constructions (XS3 exposure class according to the Spanish Structural Code [40]). Non-destructive electrochemical measurements were performed during the test in order to detect the onset of the steel corrosion and to monitor the intensity of the process. The portable GECOR 6 equipment (GEOCISA, Madrid, Spain) was used to measure the potential corrosion \(E_{corr}\), the concrete resistivity \(\rho\), and the corrosion rate \(I_{corr}\). A Cu/CuSO\({}_{4}\) (saturated) reference electrode was used. The electrochemical measurements require a wet, but not saturated, state of the concrete. In order to meet this requirement, the testing surface was sprayed with tap water 15 min before taking the readings. The test procedure was as follows: in the first phase, the pond was filled with tap water for 14 days. This was performed to check the initial corrosion state. In the second phase, the pool was kept empty for 7 days. This is a drying stage of the specimens previous to the next phase. In the third and last phase, the wetting-drying cycles were applied with periodic surface application of a certain amount of a 0.5 M NaCl solution. See Figure 1 and Table 2 for details of the cycles, whose duration was of four or five days. The electrochemical measurements were taken with an approximate weekly periodicity during the whole accelerated corrosion test, which lasted about 36 weeks.  
\begin{table}
\begin{tabular}{c c} \hline
**Day** & **Action** \\ \hline
1 & Spread 65 mL of 0.5 M NaCl solution on the tested concrete surface inside the pond \\
2 & Allow the specimen to dry 1 \\
3 & Moisten the specimen during 3 h by ponding with 300 mL of tap water. Empty the pond \\  & and take the electrochemical measurements: \(\rho\), \(E_{corr}\) and \(I_{corr}\) \\
4 & Allow the specimen to dry 1 \\ \hline \end{tabular} \({}^{1}\) In case any of the dry periods were coincident with a weekend, the drying time was extended to two days.  
\end{table}
Table 2: Details of the wetting–drying cycles with application of a 0.5 M NaCl solution during the accelerated corrosion test.  
Figure 1: Concrete sample for corrosion test, and the steps of the wetting–drying cycles during the corrosion test. See text and Table 2 for details.