Power washing concrete surfaces can cause real problems. Relatively inexpensive high-pressure power washing units are commonly available. Some of those units can deliver water at pressures well in excess of 6,000 pounds per second (psi)!
Moreover, it is not just high-pressure water that’s the problem. The water exits the nozzle at both a high pressure and a high velocity. The resulting momentum is great enough to dislodge not only dirt and debris but also to create flakes, popouts, and even concrete spalls. Good quality concrete will also experience accelerated wear from high-pressure power washing.
However, there exists another problem that is not so obvious and requires a little bit more thought. Concrete is both porous and permeable. It is porous because it contains millions of microscopic and submicroscopic voids. Entrained air voids are just one example of the voids within concrete. As concrete hydrates, the water-filled pore space between cement particles will fill up with hydration products thereby decreasing the permeability of the concrete.
For good quality concrete, that process takes a matter of days or weeks. For poor quality concrete, that process may never occur.
We mainly cover West Lothian and Central Scotland for Concrete & Brick Cleaning but we will travel nationwide by special request. Advice is always free with no obligation.