Stains on your concrete driveway, patio, or garage floor can make the whole area look shabby and unkempt. Prevention is preferable over removing, since removal can be a challenge. Special mats made to place under cars or near a patio grill can work wonders for catching stains. If you still end up with a stain, the following guide can help you get rid of it. Just remember to wear gloves and eye protection, as many of these cleaning agents can be caustic if you get them on your skin.
Moss and Algae
These are the easiest stains to manage on your own. Moss and algae form in damp conditions. Keeping the concrete swept and free of leaves or other debris prevents most moss and algae growth. If you still end up with the greenish-black stains, a simple bleach solution can usually take care of it.
Combine about ½ cup of bleach with a gallon of water. Soak the stain with the solution and let it set for 10 to 15 minutes. Then, scrub it well with a stiff brush. You may need to repeat the process a few times to fully lift the stain.
Oil and Grease
Oil from your car or grease from your grill can be one of the hardest stains to remove. These seep deeply into the concrete, and scrubbing just spreads them around more. Instead, you need to soak the stains out of the concrete.
To do this, combine an absorbent material, such as diatomaceous earth or fuller's earth (available where concrete repair supplies are sold) with trisodium phosphate (TSP), following the label's mixing instructions. Make a paste and spread it over the stain. Leave overnight. Then, scrape it up and scrub with a brush. Repeat if necessary until the stain is lightened.
Paint generally sits on the surface of the concrete, so it can be easier to remove than oil and grease. Paint stripper, the same as you would use on wood, also works on concrete.
Simply spread the stripper over the paint and allow it to set for 10 to 15 minutes. Then, use your scraper to scrape up the paint. Once the stripper is removed, scrub the area with a wire brush to remove any remaining paint flecks and then rinse dry.
There are many concrete-repair products available made to remove stains. They all require some effort to use, but the result will be a pristine concrete surface. Talk to a company such as Roklin Systems Incorporated to learn more.