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March 25 - March 29, 2019

How do I determine when a cementitious-based mortar used to repair exterior concrete is ready to be coated?

Selected Answers

From Zenith Czora of Master Builders Solutions on March 25, 2019:
The standard practice for coating cementitious-based mortar is to allow the mortar to cure for 14 days prior to painting with water-based paints, or a minimum of 28 days when oil-based paints are used. Prior to painting, the moisture content of the substrate must be checked. The moisture content should be not more than 5.5%. The pH of the substrate should be checked also to make sure it is not too alkaline for painting. pH of 10 or less is typically desirable. The pH can be checked by using a pH paper. Using  highly-alkaline-resistant water primers are highly recommended to inhibit the occurrence of efflorescence.

From Richard Devick of UCI PAINTS on March 25, 2019:
Check the pH of the cementitious patch. Ideally, it should be less than 10. Hydrating the area with periodic water wash will help “cure” the concrete, minimize surface fissures and insure the proper strength.

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Tagged categories: Asia Pacific; Coating Application; EMEA (Europe, Middle East and Africa); Latin America; Mortars; North America

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