A growing number of architects and owners are opting for concrete flatwork that resembles slate, brick, tile, stone or even wood. Stamped concrete creates an illusion of expensive slate or tile at a fraction of the cost.
Tools for producing only a pattern are made of aluminum or plastic. The basic stamping tool is typically 2 to 3 feet long and 16 to 24 inches wide. Enough tools are needed to stamp one row across the complete width of the pour and still have an extra tool to line up the next row. Smaller hand tools are used for touch-up work and for filling in the pattern near the edge of a form or building. Stamping mats that impart texture as well as pattern are made of synthetic rubber. One advantage of using the mat tool is that controlling texture and depth of the impression doesn't require a great deal of skill. Contractors also report that mats allow them time to get a good impression in the concrete long after it would be too hard for an aluminum or plastic tool.
CONCRETE REQUIREMENTS FOR STAMPING
The concrete mix needed depends on depth of the stamped pattern. Embedding a stamping tool to a depth of 1/4 inch or more requires minimal interference from coarse aggregate. Concrete with a 3/8-inch maximum size aggregate (pea gravel) works best and enables workers to achieve a uniform imprint depth. Sidewalks or other areas with a lot of pedestrian traffic shouldn't be stamped as deeply because the grooves are a tripping hazard. In these areas and in slabs textured with rubber mats, concrete with 3/4- or 1-inch maximum size aggregate can be used.
PROCEDURES FOR STAMPING CONCRETE
(1) Planning and preparation--After the layout has been planned make a list of all the tools and materials needed. (2) Initial finishing--After placement, concrete should be struck off and bullfloated. (3) Coloring concrete--After bleed water has disappeared, spread about one-half the color hardener on the surface and float it into the concrete. (4) Stamping--Judgement is required in deciding when to start stamping. The concrete must still be plastic. (5) Jointing--One way to joint stamped concrete is with leave-in-place wood strips. (6) Final texturing--Wet surface brooming should eliminate most if not all stamping imperfections. (7) Curing and sealing--Colored wax curing agents must be used because other curing methods are likely to cause surface color variations.