Corrosion Inhibition Effect of Molybdate on Fine-Grain High- Strength Reinforcement in Simulated Concrete Pore Solutions Containing Cl-

摘要

To improve the corrosion resistance of fine-grain high-strength (FGHS) reinforcement, molybdate wasinvestigated as a inhibitor. The influence of molybdate on the corrosion behavior of FGHSreinforcement in simulated concrete pore (SCP) solutions containing 1.0% or 3.5% NaCl wasevaluated using polarization, electrochemical impedance spectroscopy, and Mott–Schottky curves. Thecorrosion products were analyzed using scanning electron microscopy and energy-dispersive X-rayspectroscopy. The results revealed that upon increasing the molybdate content, the corrosion currentdensity (icorr) and donor density initially rapidly decreased and then slightly increased, while thecorrosion protection efficiency and impedance first rapidly increased and then slightly decreased. Theoptimum molybdate was 1.0 g/L. The icorr of the former (0.058 μA cm?2) was considerably less thanthat of the latter (0.250 μA cm?2). The Mott–Schottky curves for the former were continuous, whereassome of those for the latter were discontinuous owing to the depletion of a less Fe3+ in the corrosionproduct. Almost no pits on the reinforcement were observed for the former, whereas a few pits werestill observed for the latter. Molybdate exhibited good corrosion inhibition of FGHS reinforcement atlow chloride concentrations, although other or composite inhibitors should be considered for highchloride concentrations.