Moisture Mitigation

moisture mitigation

Moisture in concrete slabs is an ever present problem.

No matter how dry a concrete slab may appear, it still contains moisture, and the moisture condition can be increased by external sources. Floor covering distress and failures are often associated with high levels of moisture within the concrete floor.

The moisture condition within a slab, as measured by internal relative humidity (RH), depends on many factors including concrete mixture proportions, season when the slab is placed, environmental humidity and temperature, curing-time, and construction procedures. A concrete slab with an exposed top surface typically has a moisture gradient along the slab thickness where the RH values are lower near the top of the slab and higher at the bottom. After a floor covering is installed, the RH values become more nearly uniform along the thickness of the slab, increasing the RH values near the top. This increase in moisture condition near the surface of the slab can result in post-installation problems months or even years after installation of the floor covering.

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High moisture conditions within a concrete slab and tight project schedules pose challenges to building owners, general contractors and flooring installers. Practically all floor coverings require low moisture conditions within the concrete before allowing warranted flooring installation. If a floor is not sufficiently dry, “shotblast and seal” moisture mitigation systems require extensive surface preparation followed by layers of coatings and cementitious underlayment. Until now, contractors and installers were faced with two equally unattractive alternatives: wait and risk project delays while the floor dries, or install expensive multi-component moisture mitigation systems.