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Hybrid Corrosion Protection

Hybridkorrosionsskyddssystem för förspända betongbroar

Many reinforced concrete structures suffer from corrosion damage. Causes include salt ingress due to the application of de-icing salts during winter maintenance, exposure to marine environments and carbonation of the concrete.

TRADITIONAL CORROSION PREVENTION METHODS FOR CONCRETE

Corrosion is an electrochemical process and as such the use of electrochemical technology treatments has been very popular. Traditional treatments such as impressed current cathodic protection (ICCP) require the passage of a constant current through the concrete to arrest corrosion activity and hinder its future development. However, for prestressed concrete reinforcement there are risks of hydrogen embrittlement of the steel if the applied polarization is not strictly controlled. (Learn more in An Introduction to Hydrogen Embrittlement.)

THE NEED FOR HYBRID CORROSION PROTECTION

Standards deal with such risks by limiting the induced change in the potential of the steel reinforcement by reducing the amount of hydrogen generated as a result of water hydrolysis during the application of an electrochemical treatment such as ICCP. However the risk to the asset owner remains throughout the long-term use of an ICCP system as monitoring and adjustments are usually undertaken at annual intervals only and this may not be sufficient. An alternative approach to reduce this risk would be to apply a brief impressed current treatment delivered using an external DC power supply to re-alkalize the corrosion sites and provide long-term corrosion prevention by means of galvanic corrosion protection. This combination of electrochemical treatments is more commonly known as hybrid corrosion protection.

THE NEED FOR HYBRID CORROSION PROTECTION

Standards deal with such risks by limiting the induced change in the potential of the steel reinforcement by reducing the amount of hydrogen generated as a result of water hydrolysis during the application of an electrochemical treatment such as ICCP. However the risk to the asset owner remains throughout the long-term use of an ICCP system as monitoring and adjustments are usually undertaken at annual intervals only and this may not be sufficient. An alternative approach to reduce this risk would be to apply a brief impressed current treatment del

ivered using an external DC power supply to re-alkalize the corrosion sites and provide long-term corrosion prevention by means of galvanic corrosion protection. This combination of electrochemical treatments is more commonly known as hybrid corrosion protection.

The advantages of employing hybrid corrosion protection included:

  1. Combining the power of a traditional electrochemical system to arrest corrosion activity with the simplicity and low maintenance requirements of galvanic technologies
  2. Corrosion activity arrested immediately through a temporary energizing phase
  3. Overall lower risks of hydrogen embrittlement
  4. No need for permanent power supplies and associated annual maintenance costs
  5. It reduced access requirements for installation and monitoring
  6. Future re-energization features
  7. It significantly reduced risks of electrical short-circuits