What is concrete carbonation?
Carbonation of concrete is a natural process that occurs when carbon dioxide in the environment reacts with water or retained moisture, reducing its pH.
For a concrete to be considered an alkaline medium that protects or passivates the reinforcement, it must have pH values of around 12-13. The reduction of pH due to carbonation implies a loss of this protective capacity and, consequently, the corrosion process of the reinforcement is activated, always under the appropriate conditions.
Visible and structural causes of carbonated concrete
Over time, concrete begins the process called carbonation, although we are not aware of this phenomenon until the consequences begin to become visible. Early detection will allow the problem to be treated and solved at the root.
A thorough examination is necessary to determine if carbonation has already begun. If an analysis with rapid results is required, the most appropriate course of action is to extract a piece, preferably from the damaged area, and analyze it.
Once the results are obtained, we will be able to know to what extent the structure is affected and we will proceed to analyze the most appropriate treatment, always keeping in mind that this problem does not happen again.
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Effects of carbonation of concrete
The effect of carbonation is the oxidation of reinforcement. This process leads to an increase in their volume, which causes internal stresses in the concrete structure in the form of cracks and crazing.
Oxidation of the frame
Before starting any treatment, we must make sure that the problem is a carbonation process. Once this certainty is established, we will start with the phenolphthalein test, which is a pH indicator and that, depending on the degree, will allow us to know in depth in what state of carbonation the element is. If the pH of the element is higher than 9, it changes color and becomes pink, and if it is lower, the color remains the same.
Concrete Carbonation: The Ideal Solution to the Problem
At Molins we have the best products to treat carbonation in concrete: BETOPAINT FLEX elastic anti-carbonation paint is an elastic coating suitable for protecting concrete and mortar against carbonation. It is permeable to water vapour, allowing the support to breathe.
CORTEC MIC 2021 is a surface sealer that uses a blend of reactive silicates, surface activating agents and migratory corrosion inhibitors to protect reinforced concrete against corrosion.
It stands out for its ability to delay the onset of the corrosion process while reducing the speed of corrosion, increasing the useful life of the reinforcement, for its ease of application and because it is organic and environmentally friendly.
Finally, we have BETO PAINT , a coating for the protection of concrete and mortar against carbonation, developed based on acrylic copolymers in aqueous dispersion, single-component, waterproof, with a decorative finish and resistant to atmospheric agents.
