#MAPEITechTip: How can Alkalinity affect the installation of 'soft' floor covering?

First what is pH? pH is used to refer to the relative acidity or alkalinity of a water-based solution, ranging from 0 to 14 to indicate the pH level of a product. For each point the pH moves in either direction away from 7 (neutral), it increases by 10 times the previous number.  Acids have a pH of 0 to 7, with 0 being the most acidic and 7 being neutral, which is neither acidic nor alkaline. A reading above 7 and the products become increasingly alkaline.  High alkalinity-pH has been recognized for years as the destructive resource for damaging adhesives, primers, coating adhesion and peal-n-stick flooring products.

Optimally ‘soft’ floor covering (VCT, resilient, rubber, linoleum & carpet) adhesives should be installed on concrete substrates with pH readings between 9 and 11.  Concrete substrates in excess of a PH of11 run the risk of attacking and breaking down the adhesive, effecting bond and causing system failure. In traditional multipurpose adhesives there can be destabilization while acrylic based adhesives can begin to become unstable and not properly cure out. How can a project continue if there are PH levels in excess of 11?

In some cases you can skim coat with a cementitious patching compound helping to control ‘hot spots’ by giving a uniform PH, allowing the adhesive to dry evenly.

In extreme cases it might require using a 100% two-component solid epoxy moisture control system that complies with ASTM F3010-13 “Standard Practice for Two-Component Resin Based Membrane-Forming Moisture Mitigation Systems for Use Under Resilient Floor Coverings”.   When the ‘moisture control’ is placed as the first layer on the concrete slab it isolates the high pH from interfering with adhesive bond and mitigates adhesive degradation–avoiding a system wide resilient flooring failure.
 
For additional information on PH Test Methods, consult the following information:
 -ACI 302.2R-06 "Guide for Concrete Slabs that Receive Moisture-Sensitive Flooring Materials"
 -ASTM F710 – 11 "Standard Practice for Preparing Concrete Floors to Receive Resilient Flooring"
 -ASTM WK28850 "New Practice for the Measurement of Surface pH of Concrete Floor Slabs"