How does cathodic prevention work on new structures?

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Cathodic prevention is an electrochemical technique which involves the application of a small electrical current using anodes which have been embedded in the concrete during construction. This system can be applied to an entire structure or to selected high corrosion risk areas with the aim of preventing reinforcement corrosion when chloride penetration from the environment takes place during the service life of the structure.

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When the cathodic prevention system is operational, the negatively charged steel repels the chloride ions preventing the critical chloride concentration from initiating corrosion at the steel. In addition, the cathodic polarisation at the steel promotes the formation of hydroxide ions at the steel surface, which promotes passivity and further increases the amount of chloride ion concentration required to initiate pitting corrosion.

Cathodic prevention applied to reinforced concrete elements before corrosion has initiated requires a fraction of the energy to stop and prevent corrosion after corrosion has initiated.

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Cathodic prevention is an environmentally friendly technology. It eliminates the need for major maintenance and concrete patch repair during the service life of the structure or the need for retrofitting cathodic protection system to stop ongoing corrosion.

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Cathodic prevention can be used effectively to manage the risks associated with prestressed concrete structures which can suffer from catastrophic failure due to corrosion problems.

 Key features of this technology are:

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• Environmentally friendly: Eliminates the need for major maintenance during the service life of the structure.

• Maintenance: Regular monitoring is essential to ensure optimum operation of the system.

• Long term global/local protection: Provides effective treatment for the entire area of application. Areas of high level of corrosion especially tidal and splash zones in marine environments can be targeted with localised cathodic prevention application.

• Proven technology: Long history and an excellent track record.  

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Our recommended application:

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• Prestressed structures, chemical containment plants , defence and nuclear power structures where premature failures due to corrosion cannot be tolerated.

• Structures located in harsh marine environment with required design life in excess of 50 years.

• Critical high corrosion risk areas of all marine structures that are subject to constant wetting and drying conditions especially tidal and splash zones.

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Standard: Australian standard AS 2832.5-2008 – Cathodic protection of metals Part 5: Steel in concrete structures.