Concrete Coatings: Successful Applications
February 16, 2011
This is Chris Matt, Managing Editor of Print & E-Media with Maintenance Solutions magazine. Today's tip is successful applications of concrete coatings.
Managers should provide written specifications spelling out performance criteria, product choices, installation methods, and testing requirements. Coatings and accessories must be compatible, and this must be clear in the specifications. Accessory products also must be acceptable to the manufacturer to avoid warranty problems.
Successful installation begins with proper surface preparation, including concrete spall and crack repair. Specifications should address appropriate repair materials and processes. Removing previous coatings might involve hazardous materials, so managers need to mandate proper procedures. Installers should perform surface preparation according to the coating manufacturer's recommendations. The process typically includes sand blasting, water blasting, shot blasting, or acid etching.
Managers can consider specifying mock-ups in selected areas that are representative of the overall conditions. Mock-ups allow all parties to evaluate the process required to achieve the final application, and they provide a method to identify challenges so installers can make adjustments.
Managers also should specify adhesion tests in the mock-up areas. These tests indicate how well a product bonds to the substrate. Testing can verify adhesion for different products, surface-preparation methods, and primers.
The specifications also should mandate a check of wet-film thickness to verify the application rate is within recommended limits. Installers should apply coatings only to surfaces that are cooling or expected to remain at a steady temperature. Rising temperatures can cause vapor drive in the slab or elevated deck, leading to blisters and pinholes.
Before accepting the work, managers should specify flood testing. Checking for water leaks at terminations, joints and penetrations will show whether the installation is watertight.
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