Corrosion Management: Selecting a Corrosion Mitigation Strategy for Existing Concrete Structures, Whitmore & Ball

According to a recently completed study by the U.S. Federal Highway Administration, the annual direct cost of steel corrosion to the U.S. economy is estimated at $276 billion, or 3.1%, of the U.S. Gross Domestic Product (GDP).  If indirect costs such as loss of productivity are included, the annual cost is conservatively estimated at $552 billion, or over 6% of GDP. While these statistics are specifically related to the overall cost of corrosion, some estimates indicate that up to 30% of this total is related to corrosion in concrete structures.

Many engineers and owners, facing rising maintenance costs, recognize the significant incentive to protect existing structures from future corrosion damage by considering the use of corrosion mitigation systems.  Selecting the appropriate system is based on many factors, including the amount and level of existing chloride contamination or carbonation, amount of concrete damage, level and location of corrosion activity (localized or widespread), environmental exposure conditions, expected service life of the structure, and the cost and design life of the corrosion protection system.

Active corrosion mitigation systems (defined here as systems that supply a protective current to the reinforcing steel) generally fall into three performance categories:  corrosion prevention, corrosion control, and cathodic protection. These systems are similar in that they all provide a protective current to the reinforcing steel to mitigate corrosion activity. This article describes the differences in these systems in terms of the intended Corrosion Management application and the intensity of the protective current required to achieve the mitigation objective.  (read more)