March 2015 Job of the Month:
If an existing concrete layer is damaged, concrete surface repair may be the answer. The outdoor patio at this Buffalo Wild Wings had suffered from plenty of damage rowdy crowds and accident-prone customers. The damages were cosmetic, and they included stains from dropped pizza and wings and spills from beer. We were asked to do something about all of these blemishes.
We had a few options for this sort of concrete surface repair project. We could have simply cleaned the existing concrete surface. We would remove as many blemishes as we could from the original surface. We would then apply a color acid stain directly to the concrete layer. The acid stain would dye the concrete a new color and create colorations and variegated effects throughout the concrete surface. With any luck, the blemishes in the concrete would blend in with these variegated effects. However, it was possible that the blemishes would not blend and would, instead, create visible darker or lighter patches of concrete that would clash with the rest of the floor. This sort of concrete surface repair may not solve the problem, although we wouldn't know for certain unless we tried it out.
Another option for this concrete surface repair project would involve laying a new concrete layer on top of the existing concrete layer. First, we would clean the existing concrete layer, removing as many blemishes as we could. In the process, we would also grind the existing concrete, which would allow the new concrete to adhere to it. Then, we'd lay down a skim coat layer on top of the existing concrete layer.
Skim coats are typically used to cover up cosmetic issues like the ones on this particular patio. The new opaque concrete layer would create a new, smooth, unblemished surface that would hide any damages in the older concrete layer. This new surface could also be dyed or stained a wide range of colors, and the result would be completely free from interference from the colors and blemishes in the original concrete layer. Skim coats are thin, so less concrete is used than in other types of concrete surface repair projects. This can cut down on the cost. Skim coats are ideal for smooth surfaces, while more concrete is needed to create textures, stamps, or scored surfaces. Another advantage to a skim coat layer is that it adheres well to the existing concrete. This helps to prevent the possibility that the new concrete layer will lift up and separate from the bottom concrete layer.
At the Buffalo Wild Wings, we laid down a skim coat layer. After cleaning and grinding the existing concrete, we mixed a brown-tan color into the white skim coat mixture. We poured this on top of the existing concrete. Next, we waited until the skim coat layer had dried and hardened. We returned to the site and applied a stain, which created variegated tan-brown colorations across the surface. To protect the new concrete layer, we also applied a sealer on top of the skim coat. This is the final step of most concrete surface repair projects. The sealer protects the concrete from any new stains from dropped food and drinks or other stains. Sealers can last a long time, although they usually need to be reapplied every two to four years. It depends on how much sun exposure the sealer gets.
The new brown flooring complemented the patio's stone well and black furniture. Time would tell if the next concrete layer would withstand encounters with future customers and crowds. We waited a year and returned to the Buffalo Wild Wings to check on our concrete surface repair job. The sealer had done its job and protected the patio from blemishes. The photographs show that patio still looked great, even after a year had passed.