Evaluating BPT as a Green Corrosion Inhibitor in Synthetic Pore Solution to Protect Steel Rebars

The effectiveness of 1-benzyl-4-phenyl-1H-1,2,3-triazole (BPT) was evaluated as a potential green organic corrosion inhibitor to reduce the effects of corrosion on the reinforcing steel in concrete. The BPT inhibitor was assessed in synthetic pore solution (SPS, 8.33 g/L of NaOH + 23.3 g/L of KOH + 2.0 g/L of Ca(OH)<sub>2</sub>, pH = 13.6) in presence of 2 M NaCl and following a carbonation free and rebar passivation stabilization protocol prior Cl<sup>-</sup> addition, similar to ASTM G180. A base solution (2.35 mg/mL) of BPT in N-methyl-2-pyrrolidone (NMP) was prepared due to the limited solubility of BPT in water. Electrochemical techniques including open circuit potential, linear polarization resistance, Electrochemical Impedance Spectroscopy (EIS) and cyclic polarization curves were conducted to assess the performance of the inhibitor. The results showed that the inhibitor effectively reduces the corrosion rate of the steel rebar. The BPT optimal concentration in SPS with 2M NaCl was 3 mM BPT with an efficiency of 85.2%. Furthermore, EIS and XRD showed evidence of an adsorption mechanism by which BPT controls the corrosion rate of steel in 2 M NaCl.