How To Stop Outgassing With Concrete Coatings – Denver Colorado
How To Stop Outgassing With Concrete Coatings – A Denver Colorado Project
Outgassing from a concrete surface is a result of temperature increases causing air and moisture vapor to be emitted from the slab. Concrete by nature is porous, full of tiny air holes. Air and vapor are released when temperatures rise and are absorbed when temperatures drop.
Coatings provide a cap, restricting release of air and vapor, but can present a problem during application.
Curing Outgassing with Concrete Coatings in Denver Colorado by Fishers Concrete
The project featured here is a 2,400 sf floor in a Colorado barn. The requirement for the flooring was a high performance epoxy using our Endura E21, Self Priming, 100% solids epoxy.
The process started with mechanically grinding the surface to open up the pores , level the floor and remove any potential bond breakers in the surface. After grinding, the surface was mopped and cleaned, then bubbles were observed as a result of outgassing from the slab.
As you can see in the photos attached, after the epoxy primer was applied, tiny air bubbles formed. The solution was to lightly sand the floor and reapply a second , high build coating. It seems like a simple solution, but could have been a serious problem if Fishers Concrete did not have experience dealing with outgassing and did not have the appropriate equipment for proper sanding. Let’s not overlook the importance of being prepared, by having enough product on hand for additional coatings should a problem arise.
Outgassing and the results in floor coatings can cause a significant scare when applying. There is no way to anticipate the level of outgassing in a slab until application. The remedy, like in this case, is experience, proper equipment, problem solving skills and enough product.
In this project a final Polyurethane top coat providing abrasion and chemical resistance with UV protection was applied.
Project Summary
Location – Denver Colorado
Size – 2,400 sf
Concrete Coatings – Endura E21 and Perdure U50
Contractor – www.fishersconcrete.com
Shouldn’t a moisture test have been conducted prior to the primer application?
How much outgassing can your primer take before failing?
With quantitative data the proper moisture mitigation system can be selected prior to costly failures.
The Calcium Chloride test for MVER was not conducted. Certainly it should have been done before applying the coating. However, this was case of outgassing and not MVER. These two different things. Primer will not fail due to outgassing but it will fail due to MVER. We recommend any of the two systems – Perdure MVT or Perdure MVT+ to mitigate the MVER.