ForConstructionPros.com

By Ted Huck, MATCOR, Inc.

Successful contractors understand the importance of adding value to their clients' projects. One of the best ways to do this is to offer additional services that provide a cost-effective benefit to the client. Cathodic protection, known as CP in the industry, is exactly the type of additional service that adds long-term value to a concrete repair job and is appealing to building owners. Contractors should be encouraging their clients to consider cathodic protection when major repair projects are undertaken. The first reason is the most important -- quite simply, cathodic protection stops the repair cycle by preventing further corrosion. When the client/owner completes a major concrete repair only to find that more corrosion is occurring just a few years later, there is an unhappy client eager to blame the initial repair contractor. Cathodic protection stops future corrosion which in turn stops the vicious restoration cycle.

The second reason that contractors should encourage their clients to consider cathodic protection is equally important -- it affords the contractor an opportunity to provide a valuable additional service while increasing the profits of a particular job. For many applications, CP systems can be easily installed by any capable concrete repair contractor, following some basic instructions. This article will discuss the basic steps of how to install a CP system, providing long-term value to the client and opportunity to the contractor.

How does cathodic protection work?
In the simplest terms, a small DC electrical current is discharged off of an anode and flows through the concrete to the reinforcing steel. This protective current prevents corrosion from occurring. The simplest and most cost effective impressed current cathodic protection systems for balconies, walkways, garages and many other applications utilizes tiny wire anodes covered with conductive coatings that can be painted over the newly-repaired concrete. A small transformer/rectifier converts AC power available at the site to DC power to provide the negative charge, which is used to arrest the natural corrosion process. Typically these systems use very little power -- not much more than a conventional 120 Watt electric light bulb. The contractor has a wide range of decorative top coats available to finish the process while meeting the aesthetic requirements of the project. For more than 20 years, this proven technology has been employed successfully on numerous installations in coastal environments.

How is it installed?
Installing the impressed current cathodic protection system is very integrated with the restoration project. The system is installed during the restoration and coating phase of the concrete repair adding minimal additional time to the overall project. The system consists of four basic components:

Reference Electrodes -- These are buried between the top and bottom mat of the concrete and provide a test point to confirm that the reinforcing steel is being properly protected.