Cathodic Protection of Reinforced concrete infrastructure using MMO-Coated Titanium Alloy Bars

ASTM B1009 titanium alloy bars (TiABs), which are chemically and mechanically equivalent to Grade 5 titanium, have recently gained attention as dual-purpose materials for near-surface-mounted retrofit (NSMR) of concrete. These bars offer both structural reinforcement and corrosion protection when used as anodes in impressed current cathodic protection (ICCP) systems. While TiABs without mixed metal oxide (MMO) coating provide inherent corrosion resistance as an ICCP anode, their effectiveness in ICCP applications may be limited. This study evaluates the electrochemical behavior of iridium-based MMO coatings on TiABs that are designed as ICCP anodes. Open circuit potential (OCP) measurements showed that both uncoated and coated metals stabilized at similar potentials, while uncoated bars initially exhibited more active behavior. Additionally, linear polarization resistance (LPR) results revealed that MMO-coated TiABs exhibit approximately three times higher reactivity compared to bare TiABs. Electrochemical impedance spectroscopy (EIS) further confirmed that MMO-coated TiABs possess significantly greater conductivity, making them a superior option for use as anodes in ICCP systems. Studies on long-term performance also show that MMO coated bars are better suited for the dual-purpose application.