Improper pressure washing can damage concrete. High pressure water on uncured concrete is a recipe for disaster and a pressure washer in the wrong hands can cause many thousands of dollars in damage in mere minutes. In this article, we will explain how pressure washing can damage concrete, how to avoid it, and what to do if you damage concrete while pressure washing.
Concrete that has not had enough time to cure will be easily damaged at the surface when being pressure washed. As you may guess, the high pressures are to blame.
Concrete cures over a long time and at different times in the process concrete can take different pressures. In general and under normal conditions, concrete is safe to walk on after 48 hours, safe to drive on after 7 days, and safe for nearly all normal activity after 28 days. However, this is under normal conditions. Temperatures below 60 degrees and low humidity can dramatically slow the curing process.
Concrete continues to strengthen over incredibly long time periods. The University of Wisconsin-Madison did a 113-year concrete strength study and found that in general, concrete continues to get stronger with more time passing. However, you won’t need to wait that long to wash your driveway. At EcoWash our rule of thumb is that concrete can be washed after curing for 2 years. Before then, just let it be or use a low-pressure washing method to remove dirt or grime.
If your concrete is getting algae, rust stains, dirt, or oil on it during those first two years, we recommend contacting a professional pressure washing company to find a low-pressure approach to cleaning your concrete. These methods generally include specialized chemicals for the exact type of stains or grime, a hard-bristled broom to help the chemicals soak into the porous surface, and a low-pressure washing of the concrete’s surface.
If you have already damaged your concrete with a pressure washer, the first step should be assessing the level of damage caused. From lowest to highest concern we have streaks, then etching, and then chipping.
If streaks are your issue, the concrete likely has no damage and instead was washed with an underpowered machine that unevenly washed the surface making it look damaged. To fix this, a higher-powered pressure washer (2800+ PSI and 2.4+ GPM) should be used. An electric pressure washer will likely not get the job done correctly due to the GPM limitations of the machinery. If you have etching, the concrete has minor damage. Etching is not only visible, but if you ran your fingers across the surface you would feel uneven and jagged portions where concrete was removed. This cannot be solved with a pressure washer and will require a concrete professional to inspect the damage. For chipping, the damage is quite severe, and medium-to-large chunks of concrete were removed. For this, please contact a concrete professional as they will likely advise new concrete to be poured to replace the missing areas.
To have your concrete washed or inspected by a local, knowledgeable professional, please get in touch with us here.