Over time, a concrete slab driveway or patio will become dirty and stained. Cleaning the slab removes the black marks that form on the concrete and stops the growth of mold and algae, which make the surface slippery when wet. Absorbing excess oils, sweeping and scrubbing the slab, and using a pressure washer are all ways to achieve this goal that can be used separately or as part of a combined cleaning program.Continue Reading
If oil stains are present on the concrete, use kitty litter to absorb any excess oil. Spread the litter over the oil, and allow it to stand overnight. The next morning, sweep up the material.
Use a heavy-duty broom to sweep away dirt and debris that have collected on the surface. Remove any dirt that has collected in the expansion joints to make later cleaning steps easier.
Mix ¼ cup of washing soda into 1 gallon of hot water. Use a long-handled scrub brush to scrub the solution into the concrete. Rinse using a garden hose.
If you are unhappy with the results from hand scrubbing the slab, try using a pressure washer. These machines are available at tool rental stores. Electric power washers are lighter in weight, but they do not develop the pressure of the gasoline models. Hot water pressure washers are the most effective, but they also require more fuel for heating the water and are much heavier.