Cleaning Concrete Pavers

House Doctor | Gary Dymski

October 11, 2001

Q. Do you have any idea how I can revive the once-vibrant colors of my concrete pavers? They are about 4 years old. A sealer was applied the second season. Power washing only brings up a salty look. They are dull and dusty-looking. - Karen Kaplan, Wantagh

A. This white powder is called efflorescence and is caused when mineral salts in concrete and concrete pavers come to the surface. To clean the surface, use a 50-50 solution of vinegar and water. First remove as much of the efflorescence as you can using a long-bristled wire brush. Sweep clean then apply the vinegar solution to the concrete with a heavy nylon brush. Let it stand for about 15 minutes, but don't let it dry. Rinse the area with cool water. You might have to do this more than once to clean the area.

If this doesn't work, you can try a 10 percent solution of muriatic acid. I'd be hesitant to use this acid unless the efflorescence was simply too much to bear. It can harm the surface of the pavers if not applied and rinsed correctly. Wear rubber gloves and eye protection, work in a well-ventilated area and keep children and animals away when using muriatic acid. To mix the solution, add one part acid to nine parts water (add the acid to the water; it's safer). Apply the acid solution the same as you applied the vinegar solution with one difference. Wet the pavers with water before applying the acid solution. The acid will fizz for a while, and you can use a nylon push broom to work it into the surface. Rinse thoroughly with water, and be careful to rinse away from plants and grass. Before you apply the acid to a large area, try it on an extra paver you kept. If it drastically changes the color or etches the surface, you might want to reconsider.

Often, efflorescence diminishes over time. If it persists, it could mean your soil or the sand beneath your pavers is excessively alkaline. My suggestion is to clean the pavers once or twice a year with the vinegar solution. After a while, you should get a more natural look. If you want a more vibrant, glossy look to your pavers, penetrating sealers that also fight stains can be applied. Again, before treating the entire surface, you might want to test these sealers on a couple of spare paving stones first. These sealers can wear away and often have to be reapplied.

House Doctor Recent columns

For more information on sealing and cleaning, first contact the manufacturer of your paving stones. You also can try the Brick Institute of America (www.bia.org) or the Interlocking Concrete Pavement Institute (www.icpi.org).