ASTM D6490-99(2014)

4.1 One of the factors affecting the performance provided by a cementitious treatment is how readily water vapor passes through it. Hence, the water vapor transmission characteristics of treatments are important in assessing their performance in practical use.

4.2 The purpose of this test method is to obtain values of water vapor transfer through treatments that range in permeability from high to low. These values are for use in design, manufacture, and marketing.

4.3 Water vapor transmission is not a linear function of film thickness, temperature or relative humidity.

4.4 Values of water vapor transmission rate (1.1 This test method covers the determination of the rate at which water vapor passes through non film forming treatments, such as silanes, siloxanes and blends of silanes/siloxanes applied to cementitious substrates.

1.2 This test method covers the use of the wet cup technique, which most closely approaches the exterior conditions for use for these materials. Other conditions can be used if agreed upon between purchaser and supplier. Agreement should not be expected between results obtained by different methods or test conditions.

1.3 The values stated in SI units of measurement are designated as the standard. Factors for conversion to inch-pound units are given in 9.2.1.1 and 9.2.2.1.

1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.