Corrosion is a complex phenomenon because it is caused by the simultaneous influence of multiple factors.
The most efficient measure to prevent corrosion is cathodic protection. The cathodic protection is regulated by numerous standards, such as EN ISO 15257, EN 12954, ISO 15589-1, EN 12696, EN 13509, EN 50162, etc.
The cathodic protection can be applied both to new structures, where it prevents the occurrence of corrosion, and to existing structures where corrosion has already occurred, where it stops further corrosion and deterioration of the structures.
The cathodic protection as a measure to stop corrosion and prolong the service life of structures may be applied to all reinforced concrete structures and metal structures that are in contact with the electroconductive environment such as soil, concrete, water, and water solutions.
In practice, the cathodic protection is mostly applied to the following structures:
♦ underground or underwater metal pipelines;
♦ steel tanks;
♦ steel ports, docks, transfer stations, sluices, pillars;
♦ reinforced concrete structures: cooling towers, piles, wastewater treatment plants, water factories, bridges, pillars, roads, garages, tunnels, prestressing cables…
CATHODIC PROTECTION FOR REINFORCED CONCRETE STRUCTURES
The cathodic protection as a measure to stop corrosion and prolong the service life of structures may be applied to all reinforced concrete structures whether they are buried, submerged or exposed to air.
The area of cathodic protection for reinforced concrete structures is regulated by the standard EN 12696 – Cathodic Protection of Steel in Concrete.
Fulfilling the criteria of this standard guarantees that corrosion will be stopped and the service life of structures will be prolonged for several decades. The cathodic protection system for reinforced concrete consists of anodes, a cathodic protection station, a performance monitoring system and cable connections.
The cathodic protection of reinforced and prestressed concrete is technically and economically justified in the construction of bridges, roads, tunnels, locks, marinas, dams, towers, buildings and other capital structures because it extends the service life by several decades while reducing maintenance costs.
Sistem katodne zaštite za armirani beton se sastoji od anoda, stanice katodne zaštite, sistema za praćenje rada i kablovskih veza.
CATHODIC PROTECTION CAN BE APPLIED BOTH TO NEW STRUCTURES UNDER CONSTRUCTION AND TO THE EXISTING ONES, WHERE CORROSION HAS ALREADY OCCURRED.
When cathodic protection is applied to existing structures, there are additional costs of providing access to the part of the structure and accompanying constructions works. The density of the required protective current is higher if the corrosion has already occurred.
When the cathodic protection system is applied to new structures, anodes, a performance monitoring system and cable connections are placed on the reinforcement before concrete is poured. The density of the protective current is much lower on these structures. The costs of cathodic protection are lower if the cathodic protection system is installed in the construction phase.
Several anodic systems can be applied depending on the required service life of anodes, limiting environmental factors, and the structure itself.
MEASURING AND MONITORING CORROSION
Measuring parameters relevant to the standards and monitoring the performance parameters of the cathodic protection system enables verification of the fulfilment of protection criteria and provides timely information to the operator.
Measurement and performance monitoring systems can be automated and connected to remote data transfer systems.
The corrosion monitoring system can be upgraded with the system for remote data reading. The connection can be based on GSM/GPRS. Remote corrosion monitoring is necessary to react promptly in the case the structure is affected.
ECONOMIC JUSTIFICATION OF PROTECTION AGAINST CORROSION
Structure maintenance costs are lower if corrosion damage is avoided.
The application of the cathodic protection is completely justified both for new and existing structures, for this system completely stops further corrosion and prolongs service life for several decades.