Tags: #ASTM #buildingdesign #buildingenclosures #buildingenvelopes #buildingmaterials #buildingproducts #buildingscience #coatings #materialsscience #mgo #researchanddevelopment #roguetesting

In this study, I examine water resistance of coated magnesium oxide under freeze-thaw cycling and intermittent hydrostatic pressure. This novel approach employs test specimens that are re-tested at each step of a multi-step cycling regimen. The effects of freeze-thaw are therefore assessed explicitly and repeatedly to offer a much-improved indicator of AWB durability.

ABSTRACT: There is a fundamental void in our understanding of how Air and Water Barriers (AWB)
perform in response to freeze-thaw cycling. Water resistance is merely implied based on physical changes
imparted by the cycle regimen. This blind spot is particularly relevant considering emerging strategies
placing AWBs outboard of exterior insulation. In this study, I describe a new approach for evaluating water resistance under freeze-thaw cycling and intermittent hydrostatic pressure. Predictive value for AWB
evaluation is vastly improved beyond considerations for test rigor, resolution, and duration.

Key takeaways:

  1. I address a leading criticism that AWBs installed outboard of exterior insulation are somehow more vulnerable to freeze-thaw cycling. That’s simply untrue as I show here for DuPont’s ArmorSeal Plus AWB.
  2. I highlight that conventional evaluation methods do not consider the effects of freeze-thaw cycling in terms of water resistance. In other words, water resistance is merely inferred based on observed physical changes in cycled barriers. Here, I present a novel test that assesses water resistance at each freeze-thaw cycle using the same specimen and test apparatus.
  3. My ongoing work with the ArmorSeal Plus AWB has shown very low water absorption, an attribute that sets it apart from many other thin-mil acrylic coatings. Indeed, its resilience to freeze-thaw cycling is likely attributed to this very property. Its marriage to MgO, a perfect match.