CoatingsPro Magazine

MAY 2015

CoatingsPro offers an in-depth look at coatings based on case studies, successful business operation, new products, industry news, and the safe and profitable use of coatings and equipment.

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36 MAY 2015 COATINGSPROMAG.COM Inspector's Corner Inspector's Corner Because moisture will always take the path of least resistance, cracks, contraction joints (sawcuts), isolation joints, and other penetrations will all provide shortcuts for moisture transmission. M oisture in concrete is one of the biggest problems we face in the coatings industry today. Proper testing and understanding the problems of moisture are necessary for the successful installation of any epoxy foor coating system. Te consultant, general contractor, coating supplier, and applicator all need to understand moisture and the efect it has on coatings. Get Testy Moisture is responsible for many types of coating failures. Some of the common ones are incomplete curing, poor adhesion, softening of applied coating, blisters, craters, and discolor- ation. Cracks and sawcuts are an avenue for moisture to escape from a concrete slab. Once a foor has been coated, the equilibrium of moisture within the slab can cause joint and crack repairs to rise. Because moisture will always take the path of least resistance, cracks, contraction joints (sawcuts), isolation joints, and other penetrations will all provide shortcuts for moisture trans- mission. Tere are no guarantees that proper inspection and testing prior to coating a concrete foor will help in identifying potential moisture-related problems. Te fve applicable ASTM standards for moisture testing are: • ASTM F1869-11: Standard Test Method for Measuring Moisture Vapor Emission Rate of Concrete Subfloor Using Anhydrous Calcium Chloride • ASTM F2170-11: Standard Test Method for Determining Relative Humidity in Concrete Floor Slabs Using in situ Probes • ASTM F2420-05: Standard Test Method for Determining Relative Humidity on the Surface of Concrete Floor Slabs Using Relative Humidity Probe Measurement and Insulated Hood (Withdrawn 2014) • ASTM D 4263-83 (2005): Standard Test Method for Indicating Moisture in Concrete by the Plastic Sheet Method • ASTM F2659-10: Standard Guide for Preliminary Evaluation of Comparative Moisture Condition of Concrete, Gypsum Cement, and Other Floor Slabs and Screeds Using Non-Destructive Electronic Moisture Meter Photos courtesy of DP Coatings What's Under the Coating? Inspecting the Concrete By Brian O'Farrell, President of DP Coatings Ltd.

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