Painting of concrete structures
Concrete painting is a more advanced process than you might think. In addition to the sheer aesthetics. that can be achieved, the right techniques and materials can also significantly improve the functionality and protection of concrete surfaces. Here is a more detailed description of the various steps and aspects of concrete painting:
Concrete condition assessment
Before painting, it is worth assessing the condition of the concrete. Newly poured concrete surfaces need to be properly seasoned, which means that they should dry for about 28 days so that any residual moisture evaporates and the structure becomes strong enough. The moisture content of the concrete can be checked using a hygrometer.
If the moisture content of the concrete is too high, the paint will not adhere well and will start to peel.
Types of paint for concrete
Acrylic paints
The most popular for domestic use, they are easy to apply and quick to dry. They are UV resistant, making them ideal for outdoor applications such as patios, walls and pavements. Acrylic paints are also easy to clean and offer a wide choice of colours.
Epoxy paints
Very durable and highly resistant to chemicals, scratches and abrasion.Used mainly in industrial premises, garages or workshops.Forms a strong coating that protects concrete from mechanical damage. The downside is the longer drying time and more complicated application process (often requires mixing with hardener).
Polyurethane paints
They offer excellent weather and chemical resistance, making them ideal for outdoor and industrial use. These paints form a flexible but durable coating, making them more resistant to cracking than epoxy paints.
Surface preparation
This is a key step that determines the success of the painting. A number of points need to be noted:
- Removing contaminants: Grease, oil, dirt, and other contaminants should be removed using a pressure washer or special detergents. If the surface is not cleaned thoroughly, the paint may adhere poorly and start to peel quickly.
- Removing old paint: If the concrete was previously painted, the old coating must be removed or sanded down. For large surfaces, grinders or special mechanical scrapers can be helpful.
- Repairing cracks and holes: All cracks or holes should be filled with cement mortar or special repair fillers. It's also a good idea to sand down any uneven areas on the surface.
- Sanding and dulling: If the concrete surface is too smooth, it's worth lightly sanding it to improve paint adhesion. This process is called surface dulling and can be done using sandpaper.
Priming
Priming a concrete surface is an important step, as it allows the paint to adhere better and prevents it from being absorbed by the concrete. The primer acts as a barrier between the paint and the porous concrete, which increases the durability of the paint coating.
Use a primer dedicated to concrete, often based on acrylic or epoxy resins.
Techniques for painting concrete
The technique for painting concrete can vary depending on the surface and the paint chosen:
Painting with a roller
This is the most common method used on larger areas, such as floors or walls. The roller allows the paint to be applied quickly and evenly
Brush painting
It is used in hard-to-reach places, such as edges or corners. The brush allows for precise painting of details.
Spray painting
This is the method used in large open spaces or for industrial applications. The paint is sprayed with special guns, allowing for quick and even coverage of large areas.
Ultimate protection and maintenance
This is a key step that determines the success of the painting. It is important to pay attention to several issues:
- Varnishing: For certain surfaces, especially in high-traffic areas (such as garages or warehouses), applying an additional layer of varnish over the paint can be considered to increase the durability of the coating.
- Impregnation: After painting, it's worth protecting the concrete with an additional impregnation layer, especially in areas exposed to moisture, such as terraces or walkways. Impregnating agents protect the concrete from water penetration and dirt.
Drying and curing time
The drying time of the paint depends on its type, but usually ranges from a few to several hours. In the case of epoxy or polyurethane paints, the full curing process can take up to several days, so it is important to follow the manufacturer’s recommendations for the interval between applying successive coats and operating the surface.
Summary
Concrete painting is not a complicated process, but it requires careful preparation and selection of appropriate materials. Properly performed painting provides not only an aesthetic appearance, but also protection against external factors, moisture and mechanical damage. Careful preparation of the surface, selection of the right paint and painting technique are key to achieving a lasting and satisfactory result.