Cathodic Protection
Since 1984Cathodic Protection (CP) is a process used to control or limit the corrosion of metal, usually steel, by making it the cathode of an electrochemical cell. The steel is protected by using another more easily oxidized "sacrificial metal" to act as an anode, typically zinc. In its simplest and likely most common form, a nail is hot dip galvanized. The steel nail is dipped in molten zinc to provide a sacrificial coating to protect it from oxidation.
GNWC has worked with the Oregon Department of Transportation (ODOT) and other highway departments to apply this same process but on a much larger scale to bridges. While the majority of modern bridges are made from concrete, the concrete relies on internal steel reinforcement to carry the tensile and shear loads in the structure. Over time chlorides and oxygen attack that steel and can compromise the structural integrity of the bridge if nothing is done to stop the corrosion. In order to lengthen the usable lifespan of the bridges, GNWC has been applying a zinc coating to these structures to slow or even halt the corrosion process. In essence the bridges are being “galvanized” similar to the nail. |
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