Heavy coats of sealer, or a buildup of sealer applied numerous times over the years, will cause moisture to become entrapped under the sealer and, in time, the sealer loses adhesion from the concrete.
One of the biggest disadvantages of concrete driveway sealing is the cost. The materials and labor required to seal a concrete driveway properly can be expensive. In addition, concrete driveways that are improperly sealed can trap moisture underneath the surface, which can lead to problems such as mold and mildew.
Sealer that is applied too heavily or too often will create an impermeable barrier and trap that water vapor beneath it. If enough pressure is created by trapped water vapor, the sealer can delaminate from the concrete surface, and might even take some of the concrete paste with it!
The culprits of blotchy concrete after sealing
When you find yourself staring at discolored concrete that has already been sealed, there are usually three potential sources of blame: The sealer was applied poorly. Not enough sealer was applied. The concrete itself had varying absorption rates.
Concrete sealers are best applied in two thin coats. The first coat of sealer acts like a primer. Most of it will disappear into the concrete surface, and the concrete will probably look fairly unattractive after the first coat. The second thin coat will provide an even finish, color enhancement and gloss.
You do not want to apply a second coat after the first coat has dried or the first coat will try to repel the second coat. The second wet-on-wet coat is applied anywhere from 1-15 minutes after the first coat is applied.
Apply the first coat, waiting at least two hours before applying the second. Check your sealant can for specific drying times. Apply two thin coats to ensure a smooth and even finish.
If you experience any dew, accidental sprinkling of water or rain as the sealant dries, the sealant can become stained, cloudy, blotchy, or discolored and it will no longer be aesthetically pleasing. Simply don't seal your paver if there is even a remote chance of rain, fog, or a drizzle.
In short, yes, sealing concrete will change the appearance of your concrete. Leaving concrete unsealed will leave it with a flat look.
Deters Color to Fade
Many people prefer using a driveway concrete sealer as it would enhance the color of stamped and exposed aggregate concrete, making it look vibrant and shiny. Also, sealing keeps the color from progressively fading.
Most concrete sealers dry fairly quickly and usually dry to touch within 1-3 hours. This is true of both penetrating and topical sealers. Penetrating sealers usually fully dry for traffic in less than 24 hours with topical sealers generally taking up to 48 hours to fully dry for traffic.
The sealant should fill the entire crack from edge to edge without oozing over the top of the crack; you can get a good look at the technique in this video from Quikrete. Use a small trowel, if necessary, to remove any excess sealant from the surface of the concrete.
Concrete sealing can stop most types of concrete fractures. This fact is especially true if the crack is a result of poor-quality work in the concrete mix or site preparation. However, sealing can prevent future damage that may start from the top layer of the concrete.
As we noted earlier, concrete sealers produce a very smooth surface on top of the concrete once it has fully cured, which gives your driveway valuable resistance to water, oil, and stains.
Outdoor concrete sealers are not only worthwhile but necessary. Experts who recommend having a concrete surface sealed are doing their customers a big favor. Without this extra layer of protection, concrete will absorb moisture and may begin to crack, spall, flake, and discolor, among other things.
The answer depends on the surface's square footage. For large surfaces such as commercial floors, a sprayer is faster and way more efficient. Finally, for small surfaces, such as garages or any other exterior surface, a paint roller or any other type of roller will do the trick. Rolling is a less expensive process.
Water-based sealers do not change the color of the decorative concrete, but solvent-based sealers darken the color by several shades. This darkening effect is called color saturation. The color saturation remains as long as the seal coat is maintained.
How Long Will The Product Last? Acrylic topical coatings have the shortest lifespan, needing re-applied every 1-3 years. Epoxy and urethane systems last between 5-10 years, closer to 5 if the surface experiences heavy traffic.
A strong enough power washer will blast most types of sealer off of concrete with ease. The trick is to make sure to pressure wash the entire surface area. For more sturdy sealers, it may take a few passes with the pressure washer to get it completely removed.
Another potential cause is rain or morning dew. It's best to wait to seal concrete until the weather is dry - ideally less than 65% humidity. The sealer needs to have 12-24 hours cure time prior to any moisture getting on it, so avoid fog or dew during this period.
A clear sealer which turns frosty white in color has delaminated from the concrete surface. This is most likely due to the coating's inability to release water vapor trapped within the concrete quickly enough to prevent pressure buildup beneath the coating.
Applying a sealer in the morning or at noontime is not recommended. The concrete surfaces of your outdoor structures during the morning may contain moisture. The presence of moisture can disrupt the properties of a solvent-based sealer, which will only generate white spots or blotchy spots on your concrete surface.
Why does concrete need to be acid washed? The acid washing of concrete is a requirement after the concrete has cured sufficiently, in order to remove surface efflorescence and to open the pores before sealing. This will help the sealer to penetrate and result in a superior bond between the sealer and the surface.