Cathodic Protection against corrosion of rebar in concrete
Concrete on its own is strong under pressure, but can be weak under tension, therefore rebar is used to give the concrete more tensile strength. Healthy concrete has not been degraded by carbonation or chloride-intrusion of internal or external influences. Healthy concrete is alkaline and provides protection for the rebar. By intrusion of chlorides of internal or external sources, like for instance additives for faster curing of concrete, sea wind or salt used for winter control operations, the acidity of the concrete can change and the layer of protection disappears. Without this protective layer and in contact with the elements, water and air, corrosion can occur on the rebar and compromise the strength of the concrete structure.
On the 20th of june 2017 we hosted a presentation at the Power Electronics convention in Den Bosch.
Tell-tale signs of corrosion of rebar in concrete:
Two ways of Cathodic Protection of Rebar in Concrete
Cathodic Protection of rebar in concrete can be applied in two different ways: Galvanic (GCP) or through Impressed Current (ICCP).Galvanic Cathodic Protection (GCP)
Galvanic Cathodic Protection uses anodes made from lesser base material than the rebar. When connected to each other the anode will oxidize instead of the rebar, therefore the term sacrificial anode is used for anodes making use of this principal, the anode sacrifices itself for rebar.Impressed Current Cathodic Protection (ICCP)
Cathodic Protection based on Impressed Current makes use of the electro-part of the electrochemical corrosion process. By placing anodes in or on the concrete and connecting an direct current power source between the anode and rebar in the concrete a potential difference has been created. Ions will be transferred through the concrete and the rebar is forced into a cathodic position, hence halting the corrosion.
ERD Power offers solutions in Impressed Current Cathodic Protection for concrete structures, but also for aquatic vessels.