Dealing with concrete corrosion
What is cathodic protection and is there another solution? Request InformationPreventing Concrete Corrosion
Reinforcing steel in concrete initially protected from corrosion by the high alkalinity provided by the cement, which stabilises the passive oxide layer on the surface of the steel. The passive layer can be destroyed by a reduction in alkalinity to below about pH 10, such as may be caused by carbonation from the atmosphere or by the presence of aggressive chloride ions (salts).
- Chloride contamination of the concrete
- Ingress from external sources such as a saltwater environment
- High salt contamination in subsoil groundwater.
What causes concrete corrosion?
Deterioration of reinforced concrete is primarily caused by poor construction practise and a high salt environment.
- Inadequate depth of cover to rebars
- Concrete cracking or spalling
- Excessively porous concrete
In the presence of oxygen and moisture, these factors combine to cause corrosion of rebars (the steel reinforcing within the concrete).
How does Cathodic Protection Work?
Cathodic protection is designed to halt all the active corrosion and prevent new sites from developing. This is achieved by using electrical currents to transfer electrons into the rebar, making it ‘passive’ to the corrosion process.
Although it has been used for immersed and buried structures for well over 100 years, Cathodic Protection of reinforced concrete by means of an impressed current has been widely used only since the early 1980s.
The relatively high electrical resistivity of concrete, compared with soil or water, and the difficulty in obtaining a uniform current spread to all the embedded steel components, have required the development of special materials and procedures.
The space for other options and co-treatment methods
Although Cathodic Protection Systems have proven success in salt water environments, they may also be considered an overkill or excessive repair method in some applications.
Equally, in some applications, cathodic protection can be effective, yet not sufficiently complete solution. This can be due to the fact, that accumulated salts are still present in the concrete, and without baseline alkalinity, unprotected areas of the rebar are still vulnerable to corrosion.
Therefore, an option to effectively restore alkalinity to the structure, would provide a more comprehensive approach to remediating concrete corrosion.
Restoring concrete alkalinity with Westox Coocon
The option to effectively remove soluble salts from concrete, present an ideal partner solution for the use of Cathodic Protection Systems.
Westox Cocoon provides a cost-effective means of reducing soluble salts, to restore alkalinity.
Cocoon is a poultice medium designed to be applied to the surface of an open capillary structure. By slowly migrating into the pores of concrete or masonry structures, Cocoon slowly withdraws soluble salts found within the surface of the structure. By reducing soluble salts, the natural and safe alkaline nature of the concrete is restored.
Want more details about concrete salt extraction?
If you’re looking for or providing treatments for concrete corrosion and would like to find out more about Westox Cocoon, Neoferma is here to help.
As distributors for Cocoon in the Middle East and Australia, our product specialists can provide the details to accurately assess the suitability for your requirements. With independent test data, proven case studies and experience in effective application, find out how Cocoon improves your treatment options for concrete corrosion.