What is Hydrophobic impregnation of concrete?
Hydrophobic impregnation of concrete is a protective treatment that prevents water and aggressive substances from infiltrating concrete surfaces. This technique employs low-viscosity liquids, creams, and gels, rich in active elements like silanes and siloxanes.
Available in water or solvent-based forms, it creates a water-repellent layer on the concrete surface without filling the pores and capillaries, effectively stopping liquid ingress through capillary action while leaving the concrete's appearance unchanged.
What is Hydrophobic impregnation of concrete used for?
The treatment is used to prevent ingress of water and therefore deterioration mechanisms such as leaching, and reinforcement corrosion due to carbonation and/or chloride contamination.
Hydrophobic impregnation of concrete is not effective in providing long term durability where deterioration has already taken place. Treatments can be applied to new structures, i.e. before the initiation of the deterioration processes, or included as part of a repair system
How does Hydrophobic impregnation of concrete work?
Hydrophobic impregnation works by applying a water-repellent treatment to the concrete's surface, changing its characteristics to repel water while allowing vapor to pass through. This transformation is achieved through the use of organosilicon compounds, such as silanes and siloxanes, which create a hydrophobic barrier. This barrier reduces the movement of moisture and chloride ions significantly, by up to 98% in some cases, compared to untreated concrete. The treatment ensures that water droplets are repelled from the surface but does not obstruct the escape of water vapor, maintaining the concrete's ability to “breathe”.
How do I repair concrete structures using Hydrophobic impregnation of concrete?
To carry out hydrophobic impregnation on concrete structures to BS EN 1504-2 the following steps must be completed:
Clean the concrete surface thoroughly to remove any dirt, dust, oil, or existing deteriorated coatings. This can involve pressure washing or mechanical cleaning.
Ensure the concrete is in good condition, free from significant defects like deep cracks or spalling. Repair any major damage before proceeding.
Assess the moisture content of the concrete. The surface should be dry for the treatment to penetrate effectively.
Choose the right hydrophobic impregnation product based on the concrete type and environmental conditions. Products should comply with EN 1504-2 standards for concrete surface protection.
Apply the hydrophobic impregnation product using a low-pressure sprayer, roller, or brush, ensuring even coverage. Follow the manufacturer’s guidelines for application rates and methods.
Allow the treated surface to dry according to the product specifications. This usually varies from a few hours to a day.
Inspect the treated surface for uniform coverage and reapply if necessary. Clean up any spills or equipment according to the product's safety instructions.
Keep detailed records of the treatment process, including products used, application rates, and conditions during application. Plan for periodic inspection to monitor the performance of the hydrophobic treatment.
What equipment and expertise are required for repairing concrete structures using Hydrophobic impregnation of concrete?
Equipment required for hydrophobic impregnation of 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.
PPE such as gloves, safety glasses, and respirators to ensure the work can be done safely and protect workers from chemical exposure.
A moisture meter to check the concrete's moisture content.
Required expertise includes:
Proficiency in surface preparation techniques to ensure the concrete is properly cleaned and ready for treatment.
Expertise in the application of hydrophobic 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 Hydrophobic impregnation of concrete?
Hydrophobic impregnation creates a strongly water-repellent concrete surface, significantly reducing water ingress and the associated deterioration risks.
By preventing water and aggressive substances such as chlorides from penetrating the concrete, hydrophobic impregnation can prolong the service life of the structure.
The treatment is invisible and does not alter the appearance of the concrete surface, maintaining the structure's original look.
Effective in coastal areas or environments exposed to de-icing salts, it reduces the risk of chloride-induced corrosion of reinforcement.
Allows for the transmission of water vapor, preventing moisture buildup within the concrete structure.
What are the disadvantages of repairing concrete structures using Hydrophobic impregnation of concrete?
The protective effects may diminish over time, necessitating periodic re-application to maintain efficacy.
Any existing damage within the concrete needs to be repaired prior to treatment, as hydrophobic impregnation cannot restore structural integrity.
Achieving uniform penetration across the concrete surface is crucial; however, it can be challenging due to variations in moisture content and porosity.
Hydrophobic coatings do not protect against carbonation.
What are the limitations of repairing concrete structures using Hydrophobic impregnation of concrete?
The success of penetration relies on the moisture condition of the concrete. For new structures, a waiting period of 2-3 months is recommended before application to allow for curing.
Application is only feasible when the concrete surface is dry, and relative humidity is low, limiting the treatment's applicability in certain climates or seasons.
Hydrophobic impregnation is not suitable for conditions where the concrete is subject to high water pressure, as it cannot withstand such stresses.
While the treatment does not alter the concrete's appearance, it also does not improve or correct any aesthetic defects present. Patch repairs made prior to impregnation will remain visible.
Ancillary information
Service disruption: No
Preliminary works: Yes
Posterior works: Yes
Time consumption: Low
Cost: Low
References and further information