Properly Sealing Cracks Before Applying Epoxy Floor Coating

Before applying any Epoxy floor coating, it’s important to properly assess the concrete and repair any damage, including sealing cracks. This will help the Epoxy coating to properly cure and not bubble or peel with time.

Assessing the Concrete Cracks

First, begin by identifying the type and cause of the cracks. This will determine the best solutions for repairing them. The most common causes of cracks are concrete flexure, thermal or drying shrinkage of the concrete, or material defects such as improper quantities in the concrete mix or improper curing during construction.

There are two types of cracks – moving and non-moving.

  • Moving cracks are generally more than 1mm wide, penetrate the full depth of the concrete, and come from excessive stress in the concrete. Moving cracks often have chipped edges from freeze-thaw and edge impacts.
  • Non-moving cracks can be from hairline to over 1mm wide, don’t usually penetrate the full depth of the concrete, and come from shrinkage during the concrete curing process. There are some non-moving cracks from concrete drying shrinkage that tend to be 1mm or wider, and penetrate deeper into the concrete up to the full depth.

Choosing the Best Crack Sealer

Once you have determined the type of crack, you need to decide on the best solution to sealing it. Filling a crack with a penetrating sealer rather than just sealing over the top, is always the strongest, longest lasting solution to repairing a crack.

Moving cracks are the most difficult to seal and your success depends on the total movement of the crack. Moving cracks should be repaired in accordance with the project specifications or American Concrete International (ACI) standards which include Low-Viscosity Epoxy, Methyl Methacrylate or High Molecular Weight Methacrylate.

There are two different methods for repairing thin non-moving cracks. The first solution is not permanent and requires reapplication. Materials such as Silane or Siloxane will render a crack hydrophobic by increasing the surface tension of the crack so that water will not penetrate it.

The second solution for repairing a non-moving crack is permanent and uses the same resin-based systems that are recommended for moving cracks, such as Low-Viscosity Epoxy, Methyl Methacrylate or High Molecular Weight Methacrylate. These materials flow into the cracks and won’t allow water to penetrate them after curing has been completed. The depth of penetration is affected by the viscosity of the material as well as the amount of time the material can penetrate the crack before curing begins.

Sealing the Crack

Begin with a clean and dry surface (no moisture for 24 hours is preferred). The concrete surface and large cracks should be blown to remove any dirt or moisture.

If there are numerous thin cracks or they are difficult to visually detect, the sealer should be done as a flood coat to the entire surface to make the cracks hydrophobic. This is done by mixing the Divot Patch, pouring it onto the concrete and spreading it with a squeegee. They can also be sprayed onto the surface and allowed to dry.

Larger cracks may require several applications before they are completely filled. The Crack Weld should be mixed and poured directly into the crack. It is critical that the entire crack is filled for it to properly seal.

Once the crack repair has cured, you can grind it flush to create an even surface to apply your Epoxy floor coating. This will prevent the repairs from showing through the coating.

All the Epoxy flooring solutions come with a lifetime adhesion warranty for your protection and peace of mind.