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Reprinted from Amrstrong Guaranteed Installation Systems 1996 ã1996 Armstrong World Industries, Inc. Pages 48-50
Curing and Parting Compounds "Some curing compounds also reduce the adhesion of resilient flooring materials, and should not be used on floors intended to be covered with resilient flooring unless these compounds are known not to interfere with adhesion." (Quote from American Concrete Institute, Ad, publication 302.1R-89, "Guide for Concrete Floor and Slab Construction.") When curing, sealing, hardening or parting compounds have been used, the following general statements can be made: a. If they contain soap, wax, oil or silicone, they must be removed before a resilient floor can be installed. They can be removed by using a terrazzo or concrete grinder, by sanding with a drum sander or by using a polishing machine equipped with a heavy duty wire brush. b.There are many materials that do not contain soap, wax, oil or silicone and are advertised as being compatible with resilient flooring adhesives. No specific statement can be made regarding their use or need for removal. Conduct a Bond and Moisture Test to determine the need for removal. If after 72 hours the bond fails, the compound must be removed. Note: In the event of adhesion failure, the responsibility for warranties and/or performance guarantees rests with the compound manufacturer and not with the manufacturer of resilient flooring and/or adhesives.
After the concrete is cured, the flooring contractor needs to ensure that it dries properly. The elimination of free water is essential for the formation of a bond between the adhesives, the flooring materials and the concrete. In the presence of free water, water-based adhesives will not set up, and solvent-type adhesives will not adhere. In the case of asphaltic adhesives already bonded to dry concrete, the asphalt will eventually be displaced by water if the availability of water is sustained. Alkaline salts in solution with moisture, which exude from drying cement or which work their way up from the earth in concrete on grade and below grade, have a tendency to prevent or destroy satisfactory bonding of adhesives by sheer physical displacement. They can leave unsightly salt deposits at the seams of sheet materials and joints of tiles. They can also have a deteriorating effect on the overall installation. Too much ground moisture can create problems for on-grade and below-grade areas of commercial and residential buildings over and beyond those relating to the installation and use of resilient flooring. These problems vary from merely slight but unpleasant dampness to actual structural damage. Moisture in a concrete slab varies as the weather changes. The amount of moisture in the slab usually approximates the dampness of the subsoil. What may be a relatively dry slab at one time can be quite different at another.
The drying of concrete is a slow process and the loss of water is a direct function of the surface area. Slow evaporation is desirable the first several days; thereafter, a tedious but necessary wait is unavoidable. Usually, suspended concrete is protected from all sources of moisture except the moisture initially in the mix and water vapor in the atmosphere. However, it should be kept damp for some time to permit chemical reaction to cure the concrete. When resilient floors are to be installed, allow suspended concrete to dry thoroughly for several months with good ventilation and, if possible, with heat. When suspended concrete is known by tests to be sufficiently dry, then a resilient floor may be installed. b. On-Grade and Below-Grade Concrete Although the concrete used for slabs at all grade levels may be identical, certain differences are important as they influence the drying. Slabs in contact with the ground are exposed to ground moisture. When covered with resilient flooring, these slabs will be approximately as moist as the soil on which they are placed. A concrete slab on grade or below grade is always damp in the absence of a perfect moisture barrier.
Bond and Moisture Test
Calcium Chloride Test
Armstrong offers the following guidelines as maximum acceptable moisture emission levels for commercial installations: Product Pounds Per 1,000 ft2 Per 24 Hours As a reminder, neither the Bond and Moisture Test nor the calcium chloride test can detect lone-term moisture conditions with on-grade or below-grade slabs. They are only indicators of moisture conditions at the time the tests are conducted.
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