A concrete rub brick can help remove stains, spots and rough patches in a concrete slab. Similar to sandpaper, the grit in the rub brick rubs away the top layer of concrete surface, leaving behind a smooth, clean surface. Using a concrete rub brick should only occur when routine cleaning fails to remove spots and stains. Continuously using the rub brick may make your concrete slab uneven.
Spray the concrete slab with a hose to remove dirt and dust.
Mix hot water with a concrete cleaner in a bucket. Follow the manufacturer's recommendations for directions on how much cleaner to add per gallon of water.
Dip a deck mop or cleaning brush into the soapy water. Clean the concrete.
Spray the concrete slab with a hose to remove soap residue. Allow the concrete to air dry.
Hold the handle of a concrete rub brick in your hand. Rub the brick, in a back-and-forth motion, against stains or uneven concrete. Continue rubbing all spots and stains until gone.
Spray down the concrete with a hose to remove concrete dust. Allow the concrete slab to air dry.