Success in Learning

Problems with Painted Concrete


The biggest problem with painted concrete is its ability to chip and flake, known as spalling. Sadly once this starts, there is nothing you can do to stop it. The primary perpetrator of spalling is water.

Well-laid concrete bases will have a plastic vapor barrier laid down first before pouring. This is simply to stop the moisture from rising up through the solid concrete to come out on top. The paint cannot cope with this effect and falls apart in chips and flakes.

Water will always try and migrate up through the earth to the surface. So unless there is a vapor barrier in the way, it will always get through. No matter how thick the concrete, the water will always get through. Even studies on painted concrete bunkers laid down in the Second World War, have shown signs of vapor penetration, due to capillary action. Any chemical bond between the paint and the concrete will be broken, due to the baking effect of sunlight upon the paint surface.

The best guarantee of success is to have the concrete foundation laid by a professional. Most staining on painted concrete, and the subsequent failure of the material, is do to the concrete foundation never having had a water barrier.

Another problem, with painted concrete, is the safety hazard it might pose. The surface becomes very slippery, and can give concern from health and safety quarters, on behalf of the public.

One method of counter acting this, is to mix the paint with fine sand or other crushed materials. However, this is not easy to do and it is hard to achieve a uniform finish across the whole surface area of the concrete.

Manufacturers have tried to combat this with various products, and some degrees of success have been achieved. This results in textured epoxy paints. Solving some, but not all of the problems.

Painted concrete walls can be achieved by preparing the surface first, and cleaning it of any grease and dirt, which might break the bond. One of the best methods of preparing a painted concrete wall, is to let nature take its course and leave it to weathering. This is to reduce surface alkalinity.

But this is not always practical, for new constructions. So one solution is to use 100% acrylic latex paint. This only requires 4 weeks of aging, due to the resistance to surface alkalinity.

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