Overlays are a modified mortar that can be applied over properly prepared concrete to revitalize, renew, or revamp existing concrete. Overlays can be installed in a number of different textures, colors, and sheen levels. Applications for an overlay system include driveways, basements, patios, walkways, and even vertical applications such as retaining walls. Overlays can be stained to give you a more decorative look or add a stencil to make your driveway or patio look like flagstone or brick.