AASHTO R 31:09(2019) Standard Practice for Evaluation of Protective Coating Systems for Structural Steel. 1 .1. AASHTO R 31 practice covers testing criteria thr evaluation of protective coating systems for use on iron and steel surfaces. It is not recommended for the evaluation of hot-dip galvanizing or metalizing. 1.2. The protective coating systems are intended for use on bridges, similar structural steel, and other ferrous metal surfaces, both new and existing, prepared by abrasive blast cleaning, which are subject to corrosive atmospheric environments, such as marine, industrial, deicing chemicals, and high humidity. 1.3. The values stated in SI units are to be regarded as the standard. 4. CLASSIFICATION Primer—Primers act as the initial barrier over the prepared steel substrate. Single-coat systems shall consist only of the primer. Primers recommended for use on structures with painted connections designed for Class B allowable stress will be evaluated for Class B slip coefficient as detailed in Section 9.1 of this standard practice. Primers intended only for use on structures as maintenance applications (i.e., blast and recoat) may not be evaluated for Class B slip coefficient as detailed in Section 9.1 of this standard practice. 4.2. Touch-Up Primer—The touch-up primer shall be as recommended by the manufcturer at the time of application. Touch-up procedures for the intermediate and finish coats shall be detailed in the product data sheets or by written submission. 4.3. intermediate coat—The intermediate coat for a three-coat system serves as a tie coat between primer and finish coat as well as a protective barrier for the structural steel. The manuficturers for each (three-coat) coating system submitted for evaluation shall recommend the appropriate intermediate coat. 4.4. Finish Coat—The finish coat for each system evaluated serves as the final barrier coating and provides the desired aesthetic finish for the surface of the structure. The manufacturers for each coating system submitted for evaluation shall recommend the appropriate finish coat.AASHTO R 31 pdf download.
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