Never Apply Integral Color to the Concrete Surface

Question:
I just purchased a home with a concrete patio that was poured 5 years ago. I was told by the previous homeowner that the person who poured the concrete added the color by hand, sprinkling it on top after the pour. The color was not mixed in with the concrete. He used 1-pound color packs that are supposed to add color to a 60-pound bag of concrete mix. The color is uniform, but every time we step on the patio, the color comes off on our shoes and appears to be flaking away. The concrete surface also appears to be somewhat soft. When moving a table the other day, I noticed that when I dragged it across the patio, it etched into the concrete. I have tried sealing the surface, but the sealant doesn't stick in all areas. What are my options? Is there anything I can do to prevent the flaking and rubbing off of the color, or do I have to remove the entire patio?

Answer:
The color packs that the contractor used are designed to integrally color concrete rather than be cast onto the surface. Integral color should never be used as a surface-applied colorant. It has no binder, so it must be mixed in with the concrete to “lock in” and bond. If it’s applied to the surface, there is no way to get a strong bond between the color and the concrete. That’s why the color on your patio is flaking off and the surface is weak. The proper product for surface application is a color hardener, which contains color, sand and cement and is broadcast on the surface and worked in while the concrete is still wet. Color hardener will actually produce a stronger surface because of the additional cement and sand contained in the product.

In this case, there is no way to strengthen the soft top layer. And applying sealer to the surface is like sealing over dust or dirt. The sealer is clinging to a weak layer, which is why it’s not adhering. You don’t need to remove the entire patio, however. The best approach is to use a power washer or grinder to remove the soft top layer until you get down to solid concrete. After removing the top layer, you can keep the concrete gray or use a microtpping overlay or stain to add back some color if desired. You can learn more about staining or overlays on The Concrete Network. Go to:
www.concretenetwork.com/concrete/concrete_resurfacing
www.concretenetwork.com/stained-concrete

Soft, flaky surface caused by improper broadcasting of
integral color on top of the concrete, rather than mixing it in.