The First Word in Protective & Marine Coatings

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October 11 - October 17, 2010

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

Selected Answers

From David Grove of Shaw Nuclear Power Services on November 9, 2010:
The criteria for what you are asking should be based strictly upon what you are trying to do. If you are going to paint the surface for barrier- type protection, then preforming a plastic sheet test is only part of the answer. I would suggest that you contact the technical service department of the coatings manufacturer for more specifics. Cementitous grout is like regular concrete and most manufacturers require a minimum cure of 28 days, but will concede to a minimum hardness and no moisture. Be careful that the plastic sheet method requires a seal around the edges. Many only use tape and do not consider that the irregular surface will invalidate the results.

From remko tas of Futuro SRL on October 26, 2010:
An inexpensive way to determine if the humidity level of the concrete is low enough to be coatedis to tape a medium- sized plastic sheet to the surface in the evening and see if there is any condensation on the inside in the morning. You can also use special humidity gauges for concrete.

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