Various Treatment Methods for Old Concrete Floors with Floor Paint

Over time, commercial concrete floors are subject to various forms of wear and tear, including corrosion from chemicals such as oils, acids and alkalis. This wear and tear can lead to surface unevenness, loss of appearance and reduced functionality. In order to restore the floor’s original appearance or improve its performance, careful preparation is essential before applying a new floor coating. This article explores the various methods of treating old concrete floor coatings.

The Importance of Surface Treatment

Before applying any floor finish, adequate surface preparation is critical. Proper surface preparation ensures that the new finish adheres effectively and maintains good long-term performance. Treatment of old concrete floors typically involves the following steps:

• Floor condition assessment: Inspect the floor for signs of damage, such as cracks, chips, or peeling paint. Knowing the extent of the damage will help determine the appropriate treatment.
• Clean surface: Remove any dirt, grease or debris from the floor. This step is critical to ensure the new paint adheres securely.

1. Mechanical Grinding

Mechanical grinding is a widely used method in floor coating, especially for old concrete floors. This technology has several advantages:

• Keep it flat: For new concrete foundations, grinding can achieve the necessary flatness and ensure a smooth surface for painting. For older concrete floors, grinding can help level out uneven areas and make the surface more uniform.
• Remove impurities: Sanding can effectively remove impurities such as mud, old paint and pollutants from the cement surface. This cleaning work is essential for laying a new coating.
• Create surface roughness: You can use different grinding wheels to create the right roughness on the old paint film. This roughness can enhance the adhesion of the new paint and ensure that the paint surface is long-lasting and durable.
• Improved aesthetics: Grinding can significantly improve the overall appearance of a concrete floor by removing old, worn layers and blemishes, making it more visually appealing before a new coat of paint is applied.

2. Mechanical Sandblasting

What is mechanical sandblasting?

Mechanical blasting, also known as abrasive blasting, is a widely used technique in industrial floor preparation. This method uses high-speed sand or steel shot to impact the concrete surface. The impact force of the abrasive can effectively remove a variety of contaminants, old coatings and residues, preparing the floor for coating.

Advantages of mechanical sandblasting

• Thorough surface cleaning: One of the main advantages of mechanical blasting is the ability to completely remove old paint films, protective agent layers and other residues from the concrete surface. Thorough cleaning is essential to ensure that the new paint adheres firmly and maintains good performance over the long term.
• Creating surface roughness: The impact of the abrasive material creates the right amount of roughness on the concrete surface. This rough texture enhances the adhesion of the new paint film, ensuring a long-lasting, durable paint film. Good surface preparation is essential to prevent the new coating from flaking or peeling.
• High efficiency: Mechanical blasting is a fast and efficient method of treating large areas of concrete. High-speed blasting allows for rapid processing, making it ideal for commercial and industrial environments where time is of the essence.

Precautions before treatment

While mechanical blasting is effective in removing solid residues, it is important to note that it cannot remove grease or oil. Therefore, proper pre-treatment is essential to ensure optimal results:

• Degrease: Before sandblasting, the concrete floor should be treated with a degreaser or cleaner to remove any grease. This step is essential to get a clean surface so that the new paint can adhere better.
• Surface inspection: After degreasing, inspect the floor for any remaining contaminants or damage. Addressing issues at this stage will further improve the efficiency of the sandblasting process.

3. Acid Etching

What is acid etching?

Acid etching is a common method for treating the exterior surface of concrete floors, especially new concrete floors. The technique involves applying a diluted acid solution to the concrete surface to remove mud, roughen the surface, and prepare it for subsequent painting. While acid etching can effectively clean and treat the surface, it is important to note that it will not remove grease, dirt, or old paint films.

Acid etching process

The acid etching process involves several key steps to ensure effective treatment and preparation of the concrete surface:

• Preliminary cleaning: Before using the acid solution, always remove any floating debris, grease and dirt from the concrete floor. Preliminary cleaning ensures that the acid solution effectively penetrates the surface and achieves the desired effect.
• Soak the surface: The concrete floor should be fully soaked in water to dilute the acid and minimize its impact on the surface. This step is critical to achieve an even etching result.
• Application of acid: Apply a hydrochloric acid solution of approximately 10% concentration to the concrete surface. The acid solution should remain on the ground for 2-4 minutes, depending on the degree of etching required.
• Rinsing: Once the etching time is over, the acid solution must be rinsed off with clean water immediately to avoid leaving any salt residue. Thorough rinsing is essential to ensure that there is no residual acid on the surface, which would otherwise affect the adhesion of the new paint.
• Multiple applications: Acid etching can be performed as many times as necessary to achieve the desired surface roughness for the coating. After each etching, rinse thoroughly to maintain the desired surface texture, similar to that of fine sandpaper.
• pH check: Before painting, it is important to ensure that the pH of the concrete surface is at or slightly above 7. This balance helps ensure optimal adhesion of the new paint.

Safety precautions

While acid etching is an effective treatment method, it is critical to take proper safety precautions during the process:

• Protective gear: Operators should wear appropriate protective gear including masks, protective clothing, rubber gloves and rubber boots to prevent contact with acid.
• Ventilation: Ensure that the work environment is well ventilated to minimize inhalation of acid fumes.
• Handling of acid: When mixing an acid solution, always add the acid to the water slowly and never the other way around. This will help prevent a violent reaction that could occur when water is poured into the acid.

4. Mechanical Chiseling

Mechanical chipping is a method of mechanically removing the top layer of cement. This technique is particularly effective for treating heavy oils and other stubborn contaminants that may have penetrated the concrete surface.

• Effectiveness: Mechanical chiseling effectively removes thick grease, oil and other residues that are difficult to remove with traditional cleaning methods. This makes it ideal for heavily soiled floors in industrial environments.
• Repair needed: It is important to note that using this method will often result in a rough surface and may require the use of a repair material to restore the appearance of the floor. After chiseling, always assess the surface condition and apply a suitable repair material to ensure a smooth and even surface.

5. Wire Brush Grinding

Wire brush grinding is a manual method designed to remove loose material from the concrete surface and expose any voids or imperfections that may have occurred during the pouring process.

• Hand or power tools: This operation can be done manually using a handheld wire brush or with the aid of a power tool (for larger areas). The choice of method depends on the workload and the operator’s preference.
• Surface preparation: Wire brushing to remove debris and create a rough texture is an effective way to prepare the surface before painting. This method is especially suitable for floors that have accumulated dust, dirt or loose particles for a long time.
• Limitations: While wire brush abrasion is effective for surface cleaning, it may not be sufficient to remove deep-seated contaminants or heavy oils. In these cases, it may be necessary to combine with other treatment methods to achieve the best results.

6. Flame Baking

Flame baking is a method of removing deep grease and dirt from concrete surfaces using flames or hot air. This technique can be effective in certain environments where conditions allow.

• Effectiveness: The intense heat from the flame breaks down and vaporizes stubborn stains, making cleaning the surface easier. This method is especially useful on greasy floors.
• Caution: However, flame roasting must be done with caution. High temperatures can damage weaker cements and may create safety hazards, such as fire risks or the release of hazardous fumes. During implementation, it is important to ensure that safety measures are in place, including proper ventilation and protective gear for operators.
• Surface assessment: After flame baking, the condition of the concrete surface must be assessed to determine if any additional treatment or repair is required before applying a new coat of paint.