Moisture Mayhem: The Enemy of Concrete Coatings

Moisture Mayhem: The Enemy of Concrete Coatings

March 1, 2024 Fred Hueston Comments Off

Moisture Mayhem: The Enemy of Concrete Coatings

Frederick M Hueston

Excess moisture in concrete is a silent threat to the success of any coating project, from epoxies to urethanes and beyond. Understanding how moisture reacts with coatings and implementing proper testing procedures are crucial for long-lasting results.

The Trapped Villain:

Concrete acts as a porous material, naturally containing some level of moisture. When a coating is applied prematurely, this moisture becomes trapped. As the water vapor tries to escape, it creates a vapor pressure beneath the coating, causing:

Delamination: The coating separates from the concrete substrate, resembling peeling sunburn.

Blistering: Bubbles form within the coating as the vapor pressure builds.

Adhesion Failure: The coating loses its bond to the concrete, compromising its effectiveness.

Even if the coating is marketed as breathable, it will still reduce the escape of moisture.

Flooding’s Lingering Impact:

Flooding events are a prime culprit for introducing excessive moisture. Even if the flood occurred months ago, the concrete may still harbor hidden water, jeopardizing the performance of any coating system.

Testing is Key:

Before embarking on any coating project, a thorough moisture evaluation is essential. This involves using a reliable moisture meter to determine the concrete’s moisture content (MC). Industry standards typically recommend an MC below 5% for optimal coating adhesion.

Addressing the Issue:

If the MC exceeds the recommended level, several strategies can be employed to dry the concrete:

Moisture Vapor Transmission (MVT) Testing: This test assesses the rate at which moisture escapes from the concrete slab.

Desiccant Dehumidification: This method utilizes specialized equipment to remove moisture from the concrete.

Chemical Treatments: Certain chemicals can promote faster drying and moisture evaporation.

The Takeaway:

Moisture is a silent saboteur of successful concrete coatings. By employing moisture testing and appropriate drying techniques, professionals can ensure a strong foundation for any coating system, maximizing its lifespan and performance.