Problem Solving Forum
May 8 - May 12, 2017
What is the best method of testing for moisture content in concrete masonry unit (CMU) walls prior to application of coatings?
Zenith Czora of Durotech Industries, Inc. on
January 11, 2018:
There are 5 standard test methods in detecting moi ...read more There are 5 standard test methods in detecting moisture in concrete. If you don't have any moisture meters, either the electrical impedance type or the radio frequency type, then the best and quickest option is using the Standard Test Method for Indicating Moisture in Concrete by the Plastic Sheet Method. This method is a qualitative test and does not really measure moisture content but shows evidence of moisture and whether the moisture is moving toward the wall, in which case the CMU wall is typically ready for coating application. This test involves covering the surface of the CMU wall with impermeable material such as plastic sheet. A 460X460-mm square of 0.1-mm thick plastic sheet is placed on the CMU wall surface and sealed around the edges with tape. After 16 to 24 hours, the sheet is removed and the area is inspected for moisture or color darkening. Color darkening occurs in some instances when the moisture movement is slow and there is still a slight dampness on the surface.