How to Seal a Concrete Driveway by Aaron Kuertz

Concrete Driveways
Many homes now have concrete driveways. Concrete is used because it is long lived, easy to maintain and aesthetically pleasing. Most driveways have a broom finish to them and while more expensive, exposed aggregate is popular, too.
A proper concrete driveway installation starts with a quality concrete mix. Air entrained concrete should be used. This means that the concrete has microscopic air bubbles trapped inside the concrete and remain there once the concrete cures. These bubbles help maintain the strength and integrity of the concrete when it expands and contracts from temperature changes. Also, any water that gets into the concrete has room to expand when it freezes and not cause spalling or scaling.
Spalling and Scaling Causes
Spalling and scaling is the deterioration that is seen in concrete surfaces. The top layer breaks down or flakes away. This exposes the stone aggregate underneath and will only get worse with time. The concrete flakes and pits lead to a weakening of the concrete. The causes of the damage vary, but they all lead back to a poor concrete mix or installation. The concrete is weak from either not having enough Portland Cement mixed in, too much water added or there not being enough air entrapment. When the water inside the concrete freezes, it expands and the top layer of concrete can break from this expansion.
De-icing Salts and Deteriorating Concrete
As salts melt snow and ice, water enters the concrete. If the temperature drops below the working temperature of the de-icing compound, the water will freeze. This increases the number of expansion cycles caused by freeze-thaw cycles. While the de-icing salt itself does not damage the concrete, the expansion of freezing water does. The de-icing salts do cause corrosion of the steel reinforcement that is used in concrete driveways. This can lead to a further weakening of the concrete used in the driveway.
Penetrating Sealers to Protect Concrete Driveways
You cannot tell just by looking at the concrete driveway if it is strong enough to withstand freezing water expansion. To be safe, you should use a penetrating siloxane/silane sealer. These penetrate below the surface of the concrete and chemically bond to it. The pores get filled and stop water from entering the concrete. And they allow the concrete to breathe and release any water vapor that is inside of them. Water can also come up from under the concrete and it must be able to escape. If it cannot and is trapped below the surface, the water will freeze and cause spalling and scaling. You should avoid silicones, epoxies and acrylics because they do not allow the water vapor to escape. The sealers leave an invisible barrier to water. They will not color, darken or change the texture of the concrete.
About the Author
This article is written by Aaron Kuertz with Applied Technologies, LLC. Aaron has been in the waterproofing industry since 1998. Applied Technologies is a manufacturer and supplier to professional waterproofing contractors and homeowners in the United States. Please visit them at www.appliedtechnologies.com/pages/content/masonry_brick_sealer.html
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