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Cathodic Protection
Anodes applied to corroded structural support

Cathodic Protection at work

Cathodic Protection (CP) is a cost effective process of arresting corrosion in existing structural supports.

CP prevents corrosion by converting all of the active sites (anodic) on a metal surface to passive sites (cathodic) by supplying electrical current from an alternate source.

Acol Ltd has employed Cathodic Protection (CP) to arrest corrosion in structural steel elements of structures with great success.

CP arrests corrosion of structural supports in structures such as buildings, bridges, dry-docks, piers and swimming pools, to name a few.

What is CP?

Cathodic Protection controls corrosion of a metal surface by making it the cathode of an electro-chemical cell. This method connects the metal to be protected to a more easily corroded ‘sacrificial metal’. Consequently, the sacrificial metal acts as an anode, or an electrode through which conventional current flows into a polarized electrical device.

In 2015, acol ltd employed Cathodic Protection to great effect in the restoration of the facade of the Shelbourne Hotel. We utilised a DuoGuard hybrid zinc anode on this project. This dual technology anode now uses a sacrificial metal (zinc) in both an impressed current and sacrificial anode role.

How the DuoGuard hybrid Cathodic Protection system works

First of all, the system drove a current from a DuoGuard anode to the steel. Then, corroding sites on the steel moved to the surface of the installed anode. As a result, this generated inhibitive hydroxide ions at the steel and drew aggressive chloride ions from the concrete to the installed anode. Finally, when our technical team completed this, they cut the impressed current.

Finally, the team connected a DuoGuard anode to the steel. This anode now acts as a sacrificial anode in a long-term preventative role.

In conclusion, with the anodes in place, a monitoring station monitors the metal remotely. If the monitoring station detects signs of corrosion at any future date, the team switches on the power. This sends a current to the in-situ anodes and tops-up the protective coat. We can carry out this whole process remotely without need for direct intervention.

Click here to learn more about the importance of Cathodic Protection to the success of our restoration work on the The Shelbourne Hotel, Dublin.