Paint splatters on concrete can be troublesome to remove due to the porous nature of concrete itself, which allows the fluid to seep down into its crevices. This is especially true when a concrete surface is not completely smooth or the paint has been sitting for a long period of time. Fortunately, standard paint stripper allows you to effectively remove stains from concrete regardless of how long the paint has been dried on it or how rough the surface is.
Mix 1 part absorbent material to 4 parts methylene chloride stripper in an aluminum can. Create just enough mixture to cover the paint spots.
Stir the mixture with a paint stirrer until it has an even consistency and looks like a thick paste. If the mixture is too thin, add a little more of absorbent material to the mixture in increments.
Spread at least a 1/4-inch layer of the paste over the paint spots with the paint stirrer. Let it sit for 20 minutes to ensure the stripper has time to loosen the paint.
Scrape the paste off the concrete with a paint scraper. Most of the paint should come off, but small spots may remain at this point.
Sprinkle scouring powder over the residual paint.
Dip a nylon brush in water and scrub the scouring powder into the concrete. Scrub until the paint stains come out.
Wash away the scouring powder suds with water. Examine the rinsed surface and scrub out any paint marks that you missed by repeating Steps 5 and 6.