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Fixing Sealer Failure on a Stamped Concrete Driveway

Question:

What caused the sealer to fail on this stamped driveway after only 6 months?

Answer:

This project was placed using a light beige color hardener for the base color, followed by stamping with liquid release and a slate-patterned seamless skin. The secondary accent color is a medium-brown acrylic/alcohol tint. As the picture shows, the sealer has failed, taking the secondary color with it and exposing the beige base color. The failures occurred only in low areas of the stamped texture and the driveway, as well as next to the control joints (not shown).

Sealer failure

There are two triggers at play here causing these failures. The first is overapplication of the secondary accent color. With most stamped concrete projects, the secondary color should make up only 10% to 20% of the visible color, whether the color is from a release powder or, as in this case, a liquid tint. On this stamped driveway, the secondary tint makes up over 90% of the visible color. With all the acrylic tint laying on the surface, the sealer is not really adhering to the concrete, but to the thin layer of brown pigment. Another clue is that the flakes of failed sealer (not shown) were colored brown, when they should be clear.

The second trigger is moisture. These failures occurred in early spring, two weeks after the area experienced a 30-inch snowstorm. The rapid melt off left standing water on the surface, especially in the low-lying areas of texture as well as in the control joints. Pour drainage and slope caused this standing water to penetrate the already weak sealer, and failure occurred. If the sealer had been well adhered, discoloration might have occurred but probably not failure. Chances are the remaining areas of the driveway will fail over time because of weak adhesion caused by overapplication of the secondary color.

The fix for this driveway is to strip all the sealer. This process usually removes the excess offending secondary color as well. Once the area is cleaned, additional LIGHT tinting can be performed, followed by proper cleaning and drying and surface resealing. Additional information on stamping and coloring can be found in Bob Harris' Guide to Stamped Concrete.

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