Cathodic protection against corrosion

Technology and protection principles

Due to high pH of concrete, reinforcing steel does not corrode, as it is maintained in a passive state - i.e. it is coated in a very thin oxide layer which is leak-proof, resistant to chemicals and current conducting. The steel is not subjected to corrosion until a change in physicochemical properties occurs under the influence of aggressive agents - carbon dioxide and chloride ions, which in time penetrate inside the reinforced concrete structure. The resulting carbonisation of concrete (neutralisation, acidification) eliminates the conditions which maintain the passive state of the reinforcing steel and ultimately causes pitting corrosion. Concrete is a good electric current conductor and, therefore, steel can be protected against corrosion with the use of the cathodic protection. Electric current causes the so-called cathodic polarisation and prevents corrosion.

The application scope of the cathodic protection is extremely wide:

  • Buildings (residential apartments, office blocks, schools, hospitals, etc.),
  • Bridges (foundations, pylons, slabs, boxes),
  • Tunnels,
  • Quays and wharves,
  • Sewage treatment plants,
  • Reservoirs,
  • Industrial plants
  • Underground parking lots.

Using cathodic protection:

  • Prevents the spread of corrosion within the whole area where anodes have been applied,
  • Extends the durability and service life of the structure,
  • Provides protection thanks to the carbonisation level of concrete,
  • Is frequently the cheapest corrosion-inhibiting solution for reinforced concrete structures,
  • Minimises the number and scope of structural repairs,
  • Ensures many-years' long corrosion protection which is monitored using the built-in sensors.