Concrete surfaces that are to be coated with a polymer floor coating or system require preparation to insure proper adhesion to maximize the performance and service life. An acceptable concrete surface should be free of loose concrete, contaminants, laitance and should be uniform and sound.
The basic procedure for preparing a concrete surface to receive a polymer floor system includes the following.
A visual inspection should be conducted of all concrete surfaces for signs of concrete defects, cracks, physical damage, chemical damage, contamination and presence of moisture.
Concrete that is loose, unsound or deteriorated must be removed to a point where sound concrete is exposed. Depending upon the extent and depth of the repair, cementitious materials from the Terrafuse product line or polymer mortars from the ICR product line may be used to restore the concrete.
There are several methods available to clean and prepare concrete surfaces for the application of a polymer floor coating system. Depending upon the degree of contamination some surface preparation methods may remove contaminants sufficiently to receive a coating system, whereas some methods and degree of contamination require washing, scrubbing and rinsing of the concrete surface prior to surface preparation. The primary goal of the surface preparation method is to create a sound profiled surface that is free of laitance and contaminants. Refer to the table below for a list of surface preparation methods.
Patching and repair of surface irregularities of concrete surfaces to fill gouges, surface air voids or transitions to other adjacent areas or finishes may be performed using polymer mortars from the ICR product line.
Cracks in concrete may be categorized as structural or non-structural. Non-structural cracks are the most common and appear as fine spider web cracks or larger more severe cracks that are generally wider, jagged and irregular shape. As a general rule, if a crack is wider than the width of a credit card, consult a concrete structural engineer to determine if the crack is structural. Most non-structural cracks may be filled with ECT-CF Epoxy Crack Filler that is specifically designed for crack repairs. Cracks may also be filled with a flexible joint filler when thicker or elastomeric flooring systems will be used.
Elastomeric crack isolation products such as ICR may be applied beneath a rigid polymer flooring system. This flexible under layer absorbs the movement of minor cracks without transferring the crack through the more rigid polymer flooring system. When a crack isolation membrane is used, cracks should be filled with an elastomeric caulking and may also be reinforced with fiberglass to help distribute stress loads created from movement.
Some polymer floor coatings are tolerant to moisture in concrete and on the surface, but most are not. Since concrete is a porous material, moisture can move through the pore structure and cause harmful effects on non-permeable polymer coatings. The use of proper vapour barriers beneath a concrete slab greatly reduces moisture vapour transmission. The period of time required to allow excess moisture to leave a new concrete surface is 28 days from time of placement, however, this does not imply that the surface is suitable to apply a polymer coating. If a system is being used in an environment where moisture content will affect the performance, test methods as in the table below may be used to determine the moisture content.
If moisture issues are determined, systems designed to reduce moisture vapour transmission can be used to prevent potential polymer floor system failures. Penetron VB225 moisture vapour emission reduction systems are effective systems that can be applied directly to a prepared concrete slab prior to the installation of a polymer floor system when moisture vapour readings are above the acceptable range indicated in the table above. For time sensitive situations where a polymer flooring system needs to be applied on a concrete surface promptly, Penetron VB225 may be applied to concrete 5-7 days after concrete placement for on-grade or below-grade applications.
For additional information or assistance regarding surface preparation or moisture issues, contact us prior to starting a project.
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