## 3 Results and Discussion
The higher the \(R_{\rm ct}\), the lower the \(C_{\rm eff,dl}\), which corroborates the previous results as the higher the impedance and the lower the capacitance the more protection the film imparts [50; 57; 58]. The results from the CPP and EIS techniques are in good agreement and prove that the fast cooling rate severely affects the development of the passive film as can be seen in the values for \(C_{\rm eff,dl}\) that were 3.06 \(\times\)\(10^{-3}\)\(\mu\)F/cm\({}^{2}\) for the normalized specimen and decreased until 8.12 \(\times\)\(10^{-4}\)\(\mu\)F/cm\({}^{2}\) for the water quenched and 1.61 \(\times\)\(10^{-3}\)\(\mu\)F/cm\({}^{2}\) for the oil quenched with subcritical annealing. Electrochemical results showed how the presence of chlorides compromised the stability of the passive film as the cooling rate increased. This is evidenced by electrochemical response and corrosion obtained for the different microstructures. Martensite promoted pitting corrosion of the CS rebars, which can be attributed to the high Gibbs free energy, which is higher than ferrite and pearlite; thus, Fe atoms are prone to anodic dissolution reaction with ions dissolved in the electrolyte, resulting in enhanced corrosion susceptibility [59]. The higher activity of martensite towards corrosion is in accordance with previous studies [36; 39; 47]. In addition, coarser grains and cementie promoted bigger pit depths as pitting corrosion causes the dissolution of the grain boundaries. It is found that wider pits correspond to large grain size [46]. Lower corrosion rates are observed in the samples that undergo subcritical annealing. This was due to the release of residual stresses and the presence of bainite, a more noble phase, compared to martensite [47]. After the exposure and polarization of the samples, OM revealed the corrosion products formed in the CS rebar and can be seen in Figure 11. The results showed how the quenched and the annealed samples displayed the most pitting corrosion. As the cooling rate increased, the pitting corrosion did as well. Finally, IFM analysis in Figure 12 show that the chloride ions promote local acidification that led to pitting corrosion. The average pit depth varied from 1 \(\upmu\)m for as received sample, 4 \(\upmu\)m after annealing, 2 \(\upmu\)m after normalizing, 5 \(\upmu\)m after water quenching, 5 \(\upmu\)m after oil quenching, 3 \(\upmu\)m after subcritical annealing after water quenching, and 3 \(\upmu\)m after subcritical annealing after oil quenching. Thus, showing the enhanced dissolution kinetics exhibited by only the quenched CS samples followed by the annealed CS samples. Figure 11: Optical microscopies of thermomechanically treated samples after testing in FA pore solution containing 0.6 M NaCl (\(\times\)5): (**a**) As received, (**b**) Annealing, (**c**) Normalizing, (**d**) Water quenching, (**e**) Oil quenching, (**f**) subcritical annealing after water quenching, and (**g**) subcritical annealing after oil quenching. Figure 10: Evolution of \(C_{\text{eff,dl}}\) and \(R_{\text{ct}}\) parameters for each thermomechanical treatment in FA pore solution containing 0.6 M NaCl. Therefore, influence on thermomechanical treatments on corrosion of CS reinforcements in synthetic geopolymer FA pore solution have been confirmed by both electrochemical and microstructural analysis.