Koster VAP Moisture Mitigation System used at a global electrical company, Plymouth

A global electrical company  in Plymouth had been suffering repeated problems with epoxy floors laid in a particular area of the massive Plymouth factory. The factory floor is approximately 30 years old and did not have a vapour barrier installed. There were elevated pH and Relative Humidity values over the whole factory, but there seemed to be one area of approximately 120m² that was having particular problems with osmotic blistering. The concrete substrate seemed quite sound, but significant out-gassing had occurred when applying the previous primers and coatings. The section of floor that was having the osmotic blister issues was within a temperature-controlled room.

Osmotic blistering is a common problem with Epoxy and Vinyl floors where there is an issue with water vapour passing from the concrete into the area immediately below the impermeable coating.  The vapour condenses as a highly alkaline liquid which destroys the bond of the adhesive or coating.  These problems can be caused when there is no functioning vapour barrier beneath a concrete slab, or where there is a vapour barrier, but the concrete has not had sufficient time to dry out prior to application of a non-permeable floor finish.

As this particular floor was 30 years old with a troublesome history Koster Aquatecnic advised that test cores should be taken, and a full investigation made using an independent laboratory.  The cores were taken by our approved VAP installer, they also tested the Relative Humidity and pH levels within the blisters.  The laboratory testing was undertaken and the sample core was subjected  to Infrared (FTIR) and Petrographic examination.  Using these tests it was able to determine the make-up of the concrete, test for oil-based contamination and check for signs of ASR (Alkali Silica Reaction).

The detailed analysis that came back showed that the concrete was quite porous, but strong enough to be shot blasted and receive our VAP treatment.  There were only trace values of contaminants.

Armed with the technical evaluation Koster Aquatecnic formulated a specification tailored for this floor.

After filling any non-moving cracks, potholes and voids with Koster VAP 2000 FS mixed with Koster thickening agent, the floor was shot blasted to a surface profile (CSP) of 3.  This is a very important stage of any VAP application as it removes any weak material and surface contaminants, as well as providing a perfect surface profile.

Application of Koster’s VAP system is normally a one coat procedure, however on this project we decided to carry out a pre-treatment with Koster KB Pox IN.  The KB Pox IN is a very low viscosity epoxy resin with good adhesion to damp surfaces.  It is flooded on to the surface to fill open pores within the surface concrete to significantly reduces outgassing.

Once the KB Pox was dry Koster VAP 2000 FS was applied with a notched squeegee and back rolled with a 10mm nap epoxy roller.

The VAP 2000 FS is our fast set vapour barrier system that is overcoatable after only 4 hours.  We also have VAP 2000 UFS which can be overcoated in 2-3 hours making overnight applications possible.

The VAP system has unrivaled adhesion to the prepared surface, can resist surface RH up to 100%, is VOC free and provides a long term resistance to water vapour transmission.  In this respect the VAP should not be confused with a moisture tolerant primer. Moisture tolerant primers will adhere to a damp surface but will not provide a published Sd value and will not provide long term resistance to vapour drive.

After 4 hours the VAP was carefully inspected prior to the application of an Epoxy Floor Top Coat within 48 hours of the VAP application.

Koster VAP systems are always installed by an approved contractor and can provide a guaranteed solution to the problems of vapour drive in both old and new concrete slabs.  Koster are one of the worlds leading authorities in the area of moisture mitigation and always provide an in depth and bespoke solution whether the project is for repair of an existing floor or in the case of new builds, prevention of future flooring issues.

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