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Sunday, 24 November 2013 15:16

Controlling Corrosion: The Solution

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The Solution: Cathodic Protection Treats Cause

The Federal Highway Administration has found that cathodic protection is the only proven technology for stopping corrosion once concrete is contaminated with salt.

In many cases the best and most economical solution is a cathodic protection system installed by specially trained NACE certified corrosion specialists at Southern Cathodic Protection Company.

 

Conventional Repair

Conventional concrete repair methods typically treat the symptoms, but not the cause of corrosion damage. Removing delaminated concrete and patching does not address the chloride contamination or lower the pH in the adjacent concrete. In fact, patching often results in a new corrosion cell in areas next to the repair work. This can actually accelerate corrosion and within a few years, significant concrete damage can occur. Meanwhile, corrosion continues to weaken the rebar.


A variety of maintenance options are available for corrosion damaged bridges, parking facilities, docks or other steel reinforced concrete structures. These include short-term patching, applying new overlays, corrosion inhibiting additives, coating the surface with membranes or sealants, replacing corroded rebars with epoxy-coated rebars or applying cathodic protection to structures. Determining the most cost-effective option requires analysis by a qualified corrosion engineer.

Some remedies tend to prevent contaminants from reaching the reinforing steel. However, these interventions do not attacking the problem at the root, i.e. the corrosion process is not stopped and the cycle may start over again.

Cathodic Protection

Certainly for new structures the use of impermeable concrete overlays, sealing membranes or coating the rebars can achieve good results, but for already contaminated concrete the only lasting solution is the use of cathodic protection. Cathodic protection systems can indeed prevent further corrosion of the rebars.

Corrosion of steel is an electrochemical process. The corrosion process is much like a battery: it consists of an anode (the corroding element) a cathode, an electrolyte, and an electrical current flowing from the anode, through the electrolyte, to the cathode, and finally returning via a metallic path. This miniture battery is the basis for all corrosion of steel in concrete. If any one of the four parts of this battery (corrosion cell) is removed, corrosion ceases.

Cathodic protection is an external electrical system which provides currents to counteract those of the corrosion cell.Cathodic protection removes one part of the corrosion cell and corrosion ceases. Cathodic protection treats the root cause of corrosion.

Read 11952 times Last modified on Sunday, 24 November 2013 18:06

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