Cathodic protection is an electrochemical technique used to prevent or arrest corrosion in reinforced concrete structures — particularly parkades in coastal and salt-contaminated environments where conventional repair approaches alone may not provide adequate long-term protection. Understanding when and how cathodic protection is appropriate can help strata councils and property managers make informed decisions about their most challenging concrete durability problems.
The Electrochemistry of Cathodic Protection
Rebar corrosion in concrete is an electrochemical process involving anodic (oxidation) and cathodic (reduction) reactions at the steel surface. Cathodic protection works by supplying a protective electrical current that shifts the entire rebar surface to a cathodic (non-corroding) state, effectively stopping the anodic dissolution reaction that produces corrosion. There are two types of cathodic protection systems used in concrete structures: impressed current cathodic protection (ICCP) and galvanic cathodic protection.
ICCP systems use an external power supply to deliver a controlled direct current through anodes embedded in or applied to the concrete surface. Galvanic systems use sacrificial zinc anodes — either embedded in the concrete during repair or applied to the surface as a spray or sheet — that preferentially corrode to provide protection to the rebar. ICCP systems provide more flexible control over the protection level but require ongoing power supply and monitoring. Galvanic systems are passive but provide lower, less adjustable protection currents.
When Cathodic Protection Is Appropriate for Vancouver Parkades
Cathodic protection is most valuable in situations where chloride contamination is widespread throughout the concrete structure — making conventional repair (which requires removing all chloride-contaminated concrete to interrupt the corrosion cell) prohibitively expensive. For coastal Metro Vancouver parkades with significant deicing salt history or marine salt exposure, cathodic protection can arrest active corrosion and extend the service life of the structure without the need for full chloride removal.
It is also used as a protective measure in concrete repairs to prevent the halo effect — the accelerated corrosion that occurs at the perimeter of conventional repairs where untreated chloride-contaminated concrete remains adjacent to the repair area. Installing galvanic anodes within repair areas is now standard practice on many Metro Vancouver parkade restoration projects. Our concrete repair services include galvanic anode installation where indicated.
Cost and Lifecycle Considerations
Cathodic protection systems require an upfront investment but can significantly extend the period between major repair interventions in structures with aggressive corrosion environments. For strata corporations managing expensive parkade assets, the lifecycle cost analysis often favours cathodic protection over repeated conventional repairs in heavily contaminated structures.
Our team assesses cathodic protection suitability as part of comprehensive parkade condition assessments. See our parkade resurfacing and waterproofing services and visit our FAQ for more on corrosion management strategies for Metro Vancouver parkades.
Contact Miyagi Construction for a free site assessment at estimate@miyagiconstruction.com or call (778) 513-7471.
Additional Resources
For more information on concrete standards and construction safety in British Columbia, visit WorkSafeBC and the CSA Group for industry standards and guidelines.
Get a Free On-Site Assessment
Tell us about your project and we'll get back to you within 24 hours. No obligation, no pressure.
