Cathodic Protection (CP)
Corrosion of reinforcing steel is the leading cause of premature deterioration in reinforced concrete structures. Cathodic protection is the only proven technique to stop corrosion in chloride‑contaminated concrete, regardless of the chloride level. It transforms the reinforcing steel from the active (corroding) state to a passive (protected) state by applying a small electrical current.
How Cathodic Protection Works
Corrosion is an electrochemical process. CP reverses the flow of electrical current so that the steel becomes the cathode (protected) and an external anode delivers current to the electrolyte (concrete).
Types of Cathodic Protection We Offer
1. Impressed Current Cathodic Protection (ICCP)
An external power source (transformer/rectifier) supplies low‑voltage DC current to mixed metal oxide (MMO) titanium anodes installed on the concrete surface or in slots. This system is adjustable and suitable for large or highly contaminated structures.
- Permanent monitoring and control.
- Long service life of anodes (50+ years).
- Ideal for bridges, parking garages, and marine structures.
2. Galvanic (Sacrificial) Cathodic Protection
Zinc or aluminum anodes are connected directly to the reinforcing steel. A natural voltage difference drives protective current. No external power is required.
- Simple, low‑maintenance.
- Suitable for smaller areas, patch repairs, and atmospheric zones.
- Often used in combination with concrete repair (zinc hydrogels or thermal spray).
Applications of Cathodic Protection
- Bridge decks, piers, and girders.
- Parking structures (ramps, slabs).
- Marine structures (jetties, docks).
- Industrial facilities exposed to chlorides.
- Buildings with carbonation or chloride attack.
Our CP Process
- Condition assessment: half‑cell potential mapping, chloride analysis, delamination survey.
- System design: anode selection, current density calculation, circuit layout.
- Installation: surface preparation, anode placement, connections, and encapsulation.
- Energising & commissioning: adjustment of current output, verification of protection criteria (100 mV depolarisation).
- Monitoring & maintenance: remote or on‑site data logging, annual performance reports.
Cathodic protection does not remove chlorides, but it stops further corrosion, allowing the structure to remain in service indefinitely.
