The concept of a novel approach to control MIC corrosion in civil structures

Abstract

Impressed current cathodic protection (CP) based on pulse technology has been proven to be a more efficient and effective alternative of traditional CP for reinforced concrete applications. Essentially, the superiority of pulse CP is in achieving the required steel polarization with otherwise reduced side effects (e.g. influence on bond strength or cement-based bulk matrix properties are minimized); further utilization of lower anodic surface is possible with pulse CP as a result of a better “current throw” at certain frequency and duty cycle of the pulse. The technique has not been tested so far with respect to microbiologically induced corrosion (MIC) and marine applications of steel structures. This paper will present the concept of recently initiated research for MIC corrosion control through the synergetic action of pulse CP and bio-based coatings. The emphasis is on steel structures for marine applications. An essential part of the expected corrosion control is based on the action of hybrid bio-based coatings, involving competitive microorganisms. The application targets self-healing with respect to MIC and hydrogen-induced damage. Control of anaerobic MIC will be one of the main goals of this research. Extending the application to reinforced concrete and underground pipe-network is also foreseen. The fundamental mechanisms with respect to MIC corrosion will be defined in parallel to the mechanisms of cathodic polarization when MIC is involved. Clarifying the reasons for steel ennoblement in anaerobic conditions under CP will be achieved and an optimum polarization level will be derived. The first step in this research will be studying the electrochemical behavior of steel in simulated environment as within aerobic, anaerobic and mixed MIC conditions (at open circuit and under cathodic polarization) and the results coupled to steel surface analysis and bacterial viability under conventional and pulse CP.