Most Common Reasons for Blistering in Concrete Epoxy Coatings

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Concrete is the most popular material used for floors, walls, countertops, driveways, walkways, sidewalks, and many other vertical and horizontal surfaces. Although concrete is extremely strong and durable, it can develop a problem called “blistering.”

Concrete Coating Blisters

Concrete Coating Blisters

Understanding ASR and NSAR

Blistering occurs within the near-surface area of a concrete slab. Known as Near-Surface Alkali Reaction, or NSAR, this problem is unique to Alkali-Silica Reaction, or ASR. With ASR, blistering of low-permeance coating systems develops, which usually takes years and results in mapping-type cracks. A gel that forms when certain conditions occur absorbs moisture and swells. An expansion follows due to an increase in pressure.

Experts have discovered that NSAR happens much closer to the surface of concrete, with smaller aggregates, and much faster than with ASR. With NSAR, blistering also develops because of a gel formation. Through osmosis, fluid builds up beneath the coating, thereby creating pressure and an imbalance of solute that attracts even more water.

What happens is that the additional water pulls through the concrete, where it serves as a semi-permeable membrane, which collects on the surface. From there, the impermeable coating that covers the surface traps the excess water, which leads to blistering.

Avoiding Blistering

To avoid the problem of blistering with the epoxy coatings on your New York concrete, a high-quality product and proper preparation of the surface are essential. Without preparation, epoxy coatings will not adhere properly. Therefore, the risk of water seeping up toward the surface exists, followed by the development of blistering.

For an aesthetically pleasing as well as strong, durable, and long-lasting concrete surface, you need to trust your concrete epoxy coatings to Specialty Concrete Services. With our extensive experience with and knowledge of concrete and epoxy coatings, it is possible to avoid blistering.

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