Prevent Concrete Dusting: Seal Your Patio To Stop It

Concrete dusting is a common issue for concrete patios. It is caused by a variety of factors, including excess water in the concrete mixture, poor curing, inclement weather, and the use of dirty aggregates. Concrete dusting can affect the durability of your patio and can also be harmful to your health. To prevent concrete dusting, it is important to use clean and uniformly shaped aggregates to create a strong concrete mix. Proper curing of the concrete is also essential, ensuring it is covered and protected from extreme temperatures. If your concrete has already cured and is experiencing dusting, you can use a concrete coating, densifier, or sealer to address the issue.

Sweep with a soft-bristled broom or vacuum to remove dust

Sweeping concrete dust away with a heavy-duty broom can scratch or damage the concrete beneath. Therefore, it is recommended to use a soft-bristled broom to avoid scratching the surface. Vacuums are also an excellent way to get rid of dust. If the concrete is outdoors, using an air blower to blow the dust away is a good tactic. Just make sure to wear a ventilation mask to avoid breathing in the airborne dust.

Concrete dusting is caused by a variety of problems, including exposure to inclement weather, insufficient curing of the concrete surface, weak or poor concrete mix design, carbonation through CO2 and H2O exposure, the use of tarnished or dirty aggregates, and the use of too much water during the finishing of the production process.

Dusting causes the concrete to become porous and uneven. To fix this issue, an expert will likely begin by grinding down the uneven surface to ensure that the applied coating is secure. If the concrete is soft enough to be gouged with a screwdriver, then aggressive grinding or shot blasting of the concrete surface will be required to remove the soft upper layers of concrete and expose the harder surface underneath.

To prevent concrete dusting, it is important to use the best available materials to cast your concrete. The aggregates used should be clean and of uniform shape to create a strong concrete mix design. It is also crucial to avoid using too much water during the finishing process, as this can lead to a weak layer of concrete at the surface.

Seal the concrete with a concrete densifier

Concrete dusting is a common issue for concrete patios. It is caused by a variety of problems, including exposure to weather, poor mixing, and rough treatment. Concrete dusting can cause serious durability concerns and is also detrimental to your health.

A concrete densifier is a chemical hardener that penetrates the concrete surface, reacting with the material to form crystals that fill the pores and increase surface density. It is a liquid applied after the concrete has cured. Densifiers are usually either silicate or lithium-based liquid products. They soak into the pores in the concrete after it is troweled, filling them in and densifying the top layer.

Densifiers do not create a membrane over the slab and do not change the appearance. Some densifiers also have curing properties. They are commonly used when polishing concrete floors. They are sprayed onto the slab, allowed to soak in, and dried before the final polishing is completed. The chemistry of the densifier reacts with unreacted cement and lime in the concrete to produce a crystalline structure within the concrete, making it less absorbent.

One of the best chemically reactive concrete densifiers to combat concrete dusting is the Lithi-Tek 4500. It is designed to strengthen, harden, and reduce the porosity of concrete. The small particle size of the Lithi-Tek 4500 allows it to penetrate to depths previously thought unattainable. This results in calcium silicate hydrate filling in the pores and voids of the concrete, making it stronger, harder, less porous, and less susceptible to concrete dusting.

Seal the concrete with RadonSeal® Penetrating Concrete Sealer

Concrete dusting is a common issue for concrete patios. It is caused by a variety of problems, including weather, poor mixing, and rough treatment. Concrete dusting can cause durability issues and is harmful to human health.

To stop concrete dusting, it is important to seal your concrete patio. RadonSeal® Plus Deep-Penetrating Concrete Sealer is a non-toxic, safe and easy-to-apply sealer that can be used for this purpose. It is designed to penetrate and seal the pores of indoor and outdoor concrete, permanently sealing, strengthening, and protecting the surface.

Step 1: Prepare the Concrete Surface

Before applying RadonSeal®, ensure that the concrete is clean, bare, and porous. Remove any paints, sealers, curing compounds, adhesives, oil, grease, or other contaminants that may interfere with the sealer's penetration. Use a vacuum or blower to remove excessive dust and loose particles. If necessary, use a concrete etcher or cleaner to increase the porosity of hard-troweled concrete surfaces.

Step 2: Test the Sealer

Concrete surfaces can vary, so it is recommended to test the sealer on a small area first. Apply RadonSeal® to a small test area to confirm sealer penetration, surface suitability, and the desired aesthetic.

Step 3: Agitate the Sealer

Before use, agitate the container thoroughly by stirring or shaking it. This will ensure that the sealer is properly mixed and ready for application.

Step 4: Dampen the Concrete Surface

Using a pump sprayer, mop, or roller, lightly dampen the concrete surface with water. This step will help improve the penetration of the sealer into the concrete.

Step 5: Apply the First Coat of RadonSeal®

Spray or roll RadonSeal® uniformly onto the surface, maintaining a continuous wetting film. Ensure that the entire surface is covered evenly.

Step 6: Apply the Second Coat

While the concrete is still damp, apply a second coat to the surface about 30 minutes after the first application. For concrete blocks, it is recommended to apply three applications.

Step 7: Rinse and Scrub the Surface

For concrete floors, it is recommended to moderately rinse the treated surface with water and scrub it with a bristle broom 30 minutes after the final application. Avoid over-applying the sealer and puddle formation.

Step 8: Clean Up

Rinse your tools with water and dispose of any unused material and empty containers according to local regulations.

Step 9: Allow Drying

Treated surfaces will begin to appear dry in 1-4 hours. Avoid foot and vehicular traffic until the surface is completely dry.

Step 10: Apply Paints or Coatings (Optional)

If desired, you can apply paints, coatings, adhesives, or patch repair compounds after a waiting period of at least 10 days. During this time, RadonSeal® will continue to react and expand inside the concrete, which may cause some purging of contaminants to the surface. Clean these contaminants when necessary.

By following these steps, you can effectively seal your concrete patio with RadonSeal® Penetrating Concrete Sealer, helping to prevent concrete dusting and improve the durability and appearance of your patio.

Paint the concrete with acrylic, urethane or epoxy

Painting your concrete patio with acrylic, urethane or epoxy is an effective way to prevent concrete dusting. Concrete dusting is caused by a variety of factors, including exposure to water, extreme temperatures, and poor mixing. This can lead to durability issues, an unsightly appearance, and health concerns. To prevent this, you can apply a coating to your concrete patio. Here's a detailed guide on using acrylic, urethane or epoxy coatings:

Acrylic Concrete Sealers

Acrylic sealers are the most common type of concrete sealer used, especially for external areas like patios. They form a protective film on top of the concrete, creating a water-resistant barrier. Acrylic sealers come in water-based and solvent-based options. Water-based acrylics offer more subdued colours or a matte finish, while solvent-based acrylics provide a glossier look and darken the surface. When applying an acrylic sealer, ensure the concrete is dry to avoid blistering or bubbling.

Epoxy Concrete Sealers

Epoxy sealers, often called "two-pack" epoxy, come as separate components that need mixing before application. They produce an extremely hard, long-lasting, and abrasion-resistant finish. Epoxy sealers are well-suited for indoor use as they are not UV stable and may yellow in sunlight. Ensure the concrete surface is completely dry before application. Epoxy sealers are ideal for floors in factories, garages, and food preparation areas.

Urethane Concrete Sealers

Urethane sealers, similar to epoxy, also come as a two-pack system. When mixed, they form a UV-resistant coating with excellent abrasion resistance. Urethane has a higher resistance to chemicals and is ideal for floors in high-traffic areas, wet areas, and enhancing the beauty of coloured concrete. Urethane coatings are more flexible and dry faster than epoxy, but they may not bond as tightly to concrete.

Application Process

Regardless of the sealer chosen, the application process typically involves the following steps:

• Thoroughly clean the concrete surface, removing any impurities.
• Allow the concrete to dry completely.
• Apply the sealer according to the manufacturer's instructions, ensuring proper mixing and application techniques.
• Allow the sealer to dry and cure fully before using the patio.

Cover the concrete with polythene or damp hessian

Covering newly laid concrete with polythene or damp hessian is a highly effective way of preventing concrete dusting. Concrete dusting is the release of powder from the surface of the concrete when it is touched or moved. It occurs when the surface of the concrete is not strong enough and is porous. A porous surface is weak and fragile and can lead to more dusting.

Covering concrete with polythene or damp hessian is a good way to prevent concrete dusting because it stops the concrete from drying out too fast. When concrete dries out too quickly, it becomes more susceptible to dusting. By covering it, you are helping to maintain a satisfactory temperature regime and prevent moisture loss. This is crucial to achieving a high level of hydration of the cement in the surface layer of the concrete and thus improving its durability.

If you are using polythene, make sure the ends of the formwork are also covered to avoid creating a 'wind tunnel'. The wind can rapidly dry out the concrete surface, leading to dusting. A good way to mount the polythene sheet is on a timber framework, clear of the surface. Alternatively, you could use liquid curing compounds that are sprayed onto the surface of the concrete, forming a semi-permeable layer.

If you are using hessian, make sure it stays damp. If it dries out, it will tend to remove moisture from the concrete, which is counterproductive.

In general, curing should be maintained for 4 to 6 days, depending on the type of cement used and the ambient conditions.

Frequently asked questions