If the concrete blocks on the outside of your house or a garden wall are looking a little worse for wear, you can resurface the wall to give it a more finished and fresh look. Concrete wall repair and resurfacing is done in basically the same way as any other concrete repair or resurfacing except you need a trowel. For best results, use a concrete resurfacer that is specifically intended for use on walls.
Remove any paints or sealers from the surface of the concrete. Use a hard-bristled brush to scrub and scrape away any loose pieces of concrete. Spray the surface with water to remove any excess dirt. Let it dry.
Use concrete repair caulk and a concrete patching compound to repair any cracks, holes or pits in the surface of the concrete. Use a putty knife or finishing trowel to level off larger patch jobs, so the patch is level and flush with the rest of the concrete surface.
Mix the concrete resurfacer per the manufacturer's instructions. Spray the wall with just enough water to dampen the surface. This will help the resurfacer adhere to the wall.
Put some of the concrete resurfacing mixture on your finishing trowel. Spread the mixture on the wall approximately 1/8-inch thick, moving from the bottom of the wall up and pushing the concrete up. Repeat the process until you've covered the entire wall.
Let the concrete dry and cure completely per the manufacturer's instructions.