Concrete, sometimes called "cement," is a very durable construction material but it tends to show dirt very easily due to its grayish coloring. Patios are often made of concrete and are very useful for outdoor relaxing and socializing. If the patio is not regularly cleaned and maintained, it will probably start looking dirty very quickly with winds carrying dirt and people tracking debris onto the concrete with their shoes. Cleaning a dirty concrete patio will help restore it to looking like new again.
Remove any furniture from the patio. You want a clear concrete slab so you can clean the patio more thoroughly.
Sweep the patio to remove any loose dust or dirt from the concrete. That will also get rid of leaves and other debris that may have been tracked onto the slab.
Use a pressure washer on the concrete to remove any remaining stains or grime from the patio. Pressure washers can be rented from home improvement stores if you don't have access to one. Angle the sprayer away from your home to both prevent dirt from being pushed against the house and to prevent the water pressure from damaging siding and trim.
Allow the concrete to fully dry to assess the progress.
Apply a degreaser to any grease stains that are still visible on the concrete. Allow the cleaner to sit on the concrete for several minutes and then scrub at it with a nylon brush. Rinse away the degreaser with warm water once you're finished.
Mix a trisodium phosphate cleaner (TSP) with water in accordance with the cleaner's instructions and apply it to the concrete with a sponge or a mop if you have any remaining stains. Always wear rubber gloves when using TSP because it is highly corrosive. Allow it to sit on the concrete for the time recommended on the packaging, then scrub it with a brush and rinse it away using a hose.
Place the patio furniture and other decoration back onto the concrete only after it has dried.