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Concrete Dec 2018

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28 CONCRETE COVERED DECEMBER 2018 COATINGSPROMAG.COM Surface Preparation Standard of finished concrete, and Table A2 provides an extensive list of surface preparation methods for concrete surfaces. A lso, changes were made to include additional and/ or updated definitions and updated references. Asked what these changes mean for users of the standard, Goodwin noted, "We worked to include clearer information with indus- try consensus on proper practice and evaluation of surface preparation, and we updated the references and definitions, added guidance on microcracking/bruising, and revised guidance on moisture testing." Surface Prep Main Focus W hile adding new information and reorganizing the standard 's content was important, just as important was removing practices that no longer reflect how the indus- try prepares concrete surfaces. A lso, some information was moved around, some new information was added, and infor- mation was removed if it was considered obsolete or outside the scope of concrete surface preparation. "A few things also went away, such as 'flame clean- ing,' which was regarded as obsolete since nobody could be found who has seen it performed in many years," said Jenkins. "Moisture requirements and curing were also treated differently by adding these to the appendix; they are important and addressed, but they aren't methods of surface preparation, so they were not included in the body of the standard." e published revised standard can be found in the NACE and SSPC stores. e committee members worked to bring together industry best practices, clarified and updated information, and updated references to make the standard more relevant to today's specifiers, contractors, applicators, inspectors, and others in the concrete and coatings industry. " To be succinct, [the revised NACE No. 6/SSPC-SP 13] means less ambiguity. If correctly used by the specifier, the contrac- tor will know exactly what method or methods he or she can use and exactly what the surface condition should be when it is finished," said Jenkins. CP Table 2 Minimum Acceptance Criteria for Concrete Surfaces Before Coatings Are Applied Property Test Method Light Service (A) Severe Service (B) Surface tensile strength and/or ASTM D7234 1.4 MPa (200 psi) min. 2.1 MPa (300 psi) min. Surface tensile strength ASTM C1583 1.4 MPa (200 psi) min. 1.7 MPa (250 psi) min. Surface profile ICRI No. 310.2 CSP 2 min. CSP 3 min. Surface cleanliness ASTM D4258 (Visible dust) No significant dust No significant dust Residual contaminants (C) ASTM F21 27,28 Water droplets wet surface immediately forming a continuous uniform film Water droplets wet surface immediately forming a continuous uniform film pH (acid etching) ASTM D4262 –1pH to +2pH change in rinse water Not Recommended Moisture content (D) and/or ASTM D4263 No visible moisture No visible moisture Moisture content (D) and/or ASTM F1869 15 g/24 hr/m 2 (3 lb/24 hr/1,000 ft 2 ) max. 15 g/24 hr/m 2 (3 lb/24 hr/1,000 ft 2 ) max. Moisture content (D) ASTM F2170 80% max. 80% max. (A) Light service refers to exposure conditions such as light traffic (i.e., foot traffic and light rubber wheeled carts), moisture, nonaggressive chemicals or freeze/thaw cycles. (B) Severe service refers to exposure conditions such as heavy machinery traffic (i.e., forklifts, heavy trucks, or steel wheeled carts), deleterious chemicals, immersion or thermal shock (e.g., hot water washing or steam cleaning). (C) Though the figures in ASTM F21 depict the assessment results on nickel specimens, the standard and water films depicted are applicable to concrete surfaces. (D) NOTE: There are two scenarios where the criteria for Moisture Content in Table 2 may not apply. The first is at or below grade or outdoor slabs or walls where it may be impossible or impractical to achieve the low level of moisture indicated. The second scenario is where moisture suppressing, or moisture tolerant coatings are specified. See Paragraph A9 in Appendix A for more information.

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