What is Concrete impregnation?
Concrete impregnation is a preventive treatment that enhances concrete surfaces by inhibiting the penetration of water and aggressive substances, which could lead to deterioration. This treatment employs low-viscosity liquids containing active components like organic polymers (acrylics, epoxies, polyurethanes), silicates (sodium and potassium), and fluorides. These substances, whether water or solvent-based, are designed to be absorbed into the concrete, partially filling the pores to form a discontinuous thin film that decreases surface porosity and increases surface strength. This method also serves to harden the concrete, boosting wear resistance and minimizing abrasion effects.
What is Concrete impregnation used for?
This treatment is used to prevent or mitigate deterioration processes involving reinforcement corrosion due to carbonation and/or chloride contamination, leaching, abrasion-erosion, freeze-thaw, External Sulfate Attack (ESA), acid attack or biological deterioration.
How does concrete impregnation work?
Concrete impregnation operates through the application of a specific product onto the concrete surface, which then penetrates deep into the substrate. The active components within the impregnation solution react with moisture present in the concrete, leading to a chemical reaction that generates a protective layer.
This layer, although thin (usually 10-100 micrometres), effectively lowers the concrete's surface porosity and enhances its strength. Besides offering a barrier against water and contaminants, the impregnation process also hardens the surface, making it more resistant to wear and abrasion, without altering the concrete's natural appearance.
How do I repair concrete structures using concrete impregnation?
To carry out impregnation on concrete structures to BS EN 1504-2 the following steps must be completed:
Evaluate the concrete surface for any damages or defects that need repair before the impregnation process.
Clean the surface thoroughly using a pressure washer to remove dirt, dust, oil, or deteriorated coatings.
Ensure the concrete is dry. Use a moisture meter to verify the moisture content is within acceptable levels for impregnation.
Choose the appropriate impregnation product based on the concrete type and environmental exposure. Options include products based on organic polymers, silicates, or fluorides.
Apply the impregnation product using a low-pressure sprayer, roller, or brush, ensuring even coverage across the surface.
Allow the impregnation product to dry and cure as per the manufacturer’s instructions. The time required can vary.
After curing, inspect the surface to ensure even coverage and perform any necessary touch-ups.
Keep detailed records of the process, including product details, application rates, and environmental conditions during application.
What equipment and expertise are required for impregnation of concrete structures?
The equipment required for impregnation of a concrete structure is limited to cheap, common, ubiquitously available tools such as:
A pressure washer for cleaning the concrete surface. Chemical or mechanical cleaning solutions may also be required where oil or deteriorated coatings are present.
A low-pressure sprayer or paint rollers/ brushes to apply the impregnation materials to the concrete surface.
A moisture meter to check the concrete's moisture content.
PPE such as gloves, safety glasses, and respirators to ensure the work can be done safely and protect workers from chemical exposure.
A suitable impregnation material such as an organic polymer, silicate, or fluoride solution.
Required expertise includes:
Proficiency in surface preparation techniques to ensure the concrete is properly cleaned and ready for treatment.
Expertise in the application of concrete impregnation products, including knowledge of spraying, rolling, and brushing methods to allow intelligent material selection.
Understanding of concrete assessment to identify any damage or conditions that might affect the impregnation process.
Familiarity with industry standards and regulations, particularly BS EN 1504-2:2004 and BS EN 1504-10:2003, to ensure compliance with quality and safety guidelines.
Ability to conduct moisture content analysis to determine the optimal timing for application.
Skills in quality control and inspection to evaluate the effectiveness of the treatment post-application.
What are the advantages of repairing concrete structures using concrete impregnation?
Concrete impregnation effectively prevents water and aggressive substances from entering the concrete, protecting against deterioration processes like carbonation and chloride ingress.
Impregnation partially fills pores and creates a thin film that densifies the pore structure, reduces porosity and can increase the concrete's surface strength, making it more resistant to wear and abrasion.
Concrete impregnation significantly improves the durability by limiting the effects of abrasion and environmental deterioration, concrete impregnation can prolong the service life of the structure.
The impregnation process does not alter the appearance of the concrete, maintaining its original look.
What are the disadvantages of repairing concrete structures using concrete impregnation?
The durability of the impregnation treatment may not match the structure's lifespan, requiring periodic maintenance and reapplication to remain effective.
If concrete has already sustained damage, impregnation must be preceded by concrete replacement or repair, as the treatment alone cannot restore structural integrity.
Effective application depends on the concrete being dry and the relative humidity being low; otherwise, the treatment may not be adequately absorbed.
Concrete impregnation, unlike hydrophobic impregnation, reduces permeability to gases. This may not be suitable for environments where moisture needs to evaporate from the concrete to avoid internal damage or where breathability is required for the material's longevity.
What are the limitations of repairing concrete structures using concrete impregnation?
As concrete impregnation only partially fills surface pores some carbonate ions can enter a tiny area of the concrete surface.
Achieving uniform penetration of at least 2 mm across the concrete surface is crucial but challenging due to varying moisture conditions in the concrete.
Concrete must be at least 2 months old before applying impregnation products to allow for curing and moisture content stabilization.
Concrete impregnation is not suitable for conditions where the concrete is subjected to high water pressure, limiting its applicability in certain environments.
While the treatment preserves the concrete's visual appearance, it does not improve or correct any pre-existing aesthetic flaws. Patch repairs made prior to impregnation will remain visible, and the treatment itself does not enhance the surface appearance.
Ancillary information
Service disruption: No
Preliminary works: Yes
Posterior works: Yes
Time consumption: Low
Cost: Low
References and further information