Sacrificial Cathodic Protection of Reinforcing Steel in Atmospherically Exposed Concrete Structures
|Publication Date:||31 March 2016|
Scope and Limitations
The provisions of this standard shall be applied under the direction of a registered professional engineer, or a person certified by NACE as a corrosion specialist or cathodic protection specialist. The professional's qualifications should include suitable experience in cathodic protection of reinforced concrete structures. Under certain circumstances, a cathodic protection system may either become a structural component or significantly affect the serviceability and structural performance of a reinforced concrete structure; therefore, review of such impact should be made by a structural engineer.
The guidelines presented here are limited to SACP on existing atmospherically exposed concrete structures. This standard applies to both conventionally reinforced concrete and prestressed reinforced concrete.
SACP systems require monitoring provisions to determine the performance and to comply with this standard. SACP systems used without monitoring systems or methods to measure their performance do not comply with this standard practice as their performance cannot be verified.
Cathodic protection is a proven technique for controlling corrosion of steel in existing structures for certain applications. However, cathodic protection neither replaces lost steel nor returns corroded reinforcement to its original diameter. Although a reinforced concrete element may appear sound by traditional inspection techniques after a SACP system is installed, it could be experiencing corrosion-related tensile stress near ruptures in localized areas. This may lead to movements, deflection, cracking, delaminations or spalls that can appear several years subsequent to the installation of the SACP system.
Sacrificial anode systems have inherent limited current output characteristics and electrochemical characteristics. Accordingly, sacrificial cathodic protection systems may not always be the best system for all combinations of structure, environment, distress, and design life
NOTE: For further information, refer to the glossary of terms in Appendix A (nonmandatory).