Concrete pH and Alkalinity Testing

The sharp scent of caustic dust fills the air during diamond grinding on a fresh slab. Technical details regarding surface chemistry can be found at allen commercial epoxy flooring tx tncraftbeermag for those managing a commercial epoxy project in Allen, TX. High alkalinity in a concrete slab often leads to catastrophic bond failure if the substrate is not properly neutralized or assessed before a primer is applied.

Understanding pH Levels in Concrete

Concrete is naturally alkaline, often sitting at a pH level between 12 and 13. This high alkalinity can trigger a chemical reaction known as saponification. This occurs when the alkaline surface reacts with the oils or resins in a coating, turning the binder into a soft, soap like substance. If this happens, the coating will peel away from the surface in large sheets. Testing the pH with litmus paper or a digital meter is a standard step before any polyurea or urethane application. We look for a level that has stabilized to ensure the chemical bond remains permanent.

The Relationship Between Alkalinity and Adhesion

A high pH level interferes with the mechanical bond created during the preparation phase. Even after shot blasting or diamond grinding, the chemical makeup of the surface dictates how well a base coat will bite into the pores. If the alkalinity is too high, the chemical reaction of the resin is interrupted. This is not just about the surface. It can affect the entire depth of the coating system, including the layers of flake or quartz sand used in decorative systems. We check the pH to ensure the substrate is ready for a heavy duty topcoat.

Testing Methods and Moisture Concerns

Beyond pH, we must also consider the moisture content of the slab. A moisture test, such as the calcium chloride test, tells us if vapor pressure will push the coating off the floor. High moisture and high alkalinity together are a recipe for failure. We perform these checks to decide if a specialized moisture mitigating primer is necessary. Without these steps, even a thick solid color system will eventually delaminate. We do not rely on visual inspections alone because the chemistry is often invisible to the naked eye.

Preparing the Substrate for Coating

Once the pH and moisture levels are confirmed, we move to mechanical preparation. This involves grinding to achieve the correct surface profile. We also address any spall or deep cracks using a high strength joint filler. Proper crack repair ensures that the movement of the slab does not telegraph through the finished floor. After the surface is clean, dry, and chemically stable, we can proceed with the application of the primer and subsequent layers of the coating system.