ASTM D6490-99(2014)

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: D6490 − 99 (Reapproved 2006) D6490 − 99 (Reapproved 2014)
Standard Test Method for
Water Vapor Transmission of NonFilm Forming Treatments
Used on Cementitious Panels
This standard is issued under the fixed designation D6490; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope
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.
2. Referenced Documents
2.1 ASTM Standards:
D823 Practices for Producing Films of Uniform Thickness of Paint, Varnish, and Related Products on Test Panels
D1193 Specification for Reagent Water
D1734 Practice for Making Cementitious Panels for Testing Coatings
D3924 Specification for Environment for Conditioning and Testing Paint, Varnish, Lacquer, and Related Materials
E104 Practice for Maintaining Constant Relative Humidity by Means of Aqueous Solutions
3. Summary of Test Method
3.1 The treated cementitious substrate is sealed to the open mouth of an assembly containing water with the treated side facing
the water, and the assembly placed in a test chamber with a controlled atmosphere maintained at 50 6 5 % relative humidity at
23 6 2°C (73.5 6 3.5°F). Periodic weighings of the assembly are made to determine the rate of water vapor movement through
the specimen.
4. Significance and Use
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 (WVT) and water vapor permeance (WVP) can be used in the relative rating of
treatments only if the treatments are tested under the same closely controlled conditions of temperature and relative humidity.
This test method is under the jurisdiction of ASTM Committee D01 on Paint and Related Coatings, Materials, and Applications and is the direct responsibility of
Subcommittee D01.47 on Concrete, Stone and Masonry Treatments.
Current edition approved June 1, 2006Dec. 1, 2014. Published June 2006December 2014. Originally approved in 1999. Last previous edition approved in 19992006 as
D6490 - 99.D6490 DOI: 10.1520/D6490-99R06.– 99 (2006). DOI: 10.1520/D6490-99R14.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’sstandard’s Document Summary page on the ASTM website.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
D6490 − 99 (2014)
5. Apparatus
5.1 Assembly, consisting of a container, typically with an opening of approximately 75 mm (3 in.) by 150 mm (6 in.). The depth
of the dish is such that there is a 20 6 5 mm (0.8 6 0.2 in.) distance between the water surface and the surface of the under surface
of the test specimen, with a water depth of at least 5 mm (0.2 in.). The assembly should be made of a noncorroding material,
impermeable to water or water vapor in order to be found acceptable. The treated cementitious substrate can be sealed with wax
or sealant to the assembly. If the assembly is made of aluminum, it must be anodized or given a protective clear coating to prevent
corrosion.
5.2 Test Chamber, with a controlled temperature and relative humidity as specified in Section 3. Air shall be circulated
throughout the chamber to maintain uniform conditions at all test locations.
NOTE 1—For maintaining constant relative humidities other than those specified in 3.1, by means of aqueous solutions, refer to procedures outlined
in Practice E104.
5.3 Analytical Balance, having an adequate capacity for the weight of the test assemblies and a sensitivity of 10 mg (0.0002
lb).
6. Reagents and Materials
6.1 Purity of Water, unless otherwise indicated, reference to water shall be understood to mean reagent water conforming to
Type IV of Specification D1193.
6.2 Sealant, such as wax for attaching the coated panel to the top of the test assembly. It must be highly resistant to the passage
of water vapor. It must not lose weight to, nor gain weight from the atmosphere in an amount, over the required period of time,
that would affect the test results by more than 2 %. It must not affect the vapor pressure in a water-filled assembly.
NOTE 2—Among acceptable sealants are (1) a 60:40 mixture of microcrystalline wax and refined crystalline parafin wax, ( 2) tissue embedding wax,
and (3) a 50:50 mixture of beeswax and rosin.
7. Test Specimen
7.1 Suggested cementitious substrates to be used should be 75 by 150 by 15 mm (3 by 6 by ⁄16 in.) as outlined in Practice
D1734. Before use, the substrates should be removed from storage in water, dried at 80 6 5°C (176 6 9°F) until a constant weight
has been reached. A constant weight shall be assumed when the specimen weighed to the nearest 0.1 g loses not more than 0.1 %
in any 4-h period. Allow specimens to cool and store at standard conditions as outlined in Specification D3924 before use.
7.2 Apply treatment to one face of the test substrates u
...