1、Designation: D6490 99 (Reapproved 2014)Standard Test Method forWater Vapor Transmission of NonFilm Forming TreatmentsUsed on Cementitious Panels1This standard is issued under the fixed designation D6490; the number immediately following the designation indicates the year oforiginal adoption or, in t
2、he case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the rate atwhich water vapor passes thro
3、ugh non film forming treatments,such as silanes, siloxanes and blends of silanes/siloxanesapplied to cementitious substrates.1.2 This test method covers the use of the wet cuptechnique, which most closely approaches the exterior condi-tions for use for these materials. Other conditions can be usedif
4、 agreed upon between purchaser and supplier. Agreementshould not be expected between results obtained by differentmethods or test conditions.1.3 The values stated in SI units of measurement aredesignated as the standard. Factors for conversion to inch-pound units are given in 9.2.1.1 and 9.2.2.1.1.4
5、 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Docu
6、ments2.1 ASTM Standards:2D823 Practices for Producing Films of Uniform Thicknessof Paint, Varnish, and Related Products on Test PanelsD1193 Specification for Reagent WaterD1734 Practice for Making Cementitious Panels for TestingCoatingsD3924 Specification for Environment for Conditioning andTesting
7、Paint, Varnish, Lacquer, and Related MaterialsE104 Practice for Maintaining Constant Relative Humidityby Means of Aqueous Solutions3. Summary of Test Method3.1 The treated cementitious substrate is sealed to the openmouth of an assembly containing water with the treated sidefacing the water, and the
8、 assembly placed in a test chamberwith a controlled atmosphere maintained at 50 6 5 % relativehumidity at 23 6 2C (73.5 6 3.5F). Periodic weighings ofthe assembly are made to determine the rate of water vapormovement through the specimen.4. Significance and Use4.1 One of the factors affecting the pe
9、rformance providedby a cementitious treatment is how readily water vapor passesthrough it. Hence, the water vapor transmission characteristicsof treatments are important in assessing their performance inpractical use.4.2 The purpose of this test method is to obtain values ofwater vapor transfer thro
10、ugh treatments that range in perme-ability 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 filmthickness, temperature or relative humidity.4.4 Values of water vapor transmission rate (WVT) andwater vapor permean
11、ce (WVP) can be used in the relativerating of treatments only if the treatments are tested under thesame closely controlled conditions of temperature and relativehumidity.5. Apparatus5.1 Assembly, consisting of a container, typically with anopening of approximately 75 mm (3 in.) by 150 mm (6 in.).Th
12、e depth of the dish is such that there is a 20 6 5 mm (0.8 60.2 in.) distance between the water surface and the surface ofthe under surface of the test specimen, with a water depth of atleast 5 mm (0.2 in.). The assembly should be made of anoncorroding material, impermeable to water or water vapor i
13、norder to be found acceptable. The treated cementitious sub-strate can be sealed with wax or sealant to the assembly. If theassembly is made of aluminum, it must be anodized or given aprotective clear coating to prevent corrosion.1This test method is under the jurisdiction of ASTM Committee D01 on P
14、aintand Related Coatings, Materials, and Applications and is the direct responsibility ofSubcommittee D01.47 on Concrete, Stone and Masonry Treatments.Current edition approved Dec. 1, 2014. Published December 2014. Originallyapproved in 1999. Last previous edition approved in 2006 as D6490 99 (2006)
15、.DOI: 10.1520/D6490-99R14.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 B
16、arr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States15.2 Test Chamber, with a controlled temperature and relativehumidity as specified in Section 3. Air shall be circulatedthroughout the chamber to maintain uniform conditions at alltest locations.NOTE 1For maintaining const
17、ant relative humidities other than thosespecified in 3.1, by means of aqueous solutions, refer to proceduresoutlined in Practice E104.5.3 Analytical Balance, having an adequate capacity for theweight of the test assemblies and a sensitivity of 10 mg (0.0002lb).6. Reagents and Materials6.1 Purity of
18、Water, unless otherwise indicated, reference towater shall be understood to mean reagent water conforming toType IV of Specification D1193.6.2 Sealant, such as wax for attaching the coated panel tothe top of the test assembly. It must be highly resistant to thepassage of water vapor. It must not los
19、e weight to, nor gainweight from the atmosphere in an amount, over the requiredperiod of time, that would affect the test results by more than2 %. It must not affect the vapor pressure in a water-filledassembly.NOTE 2Among acceptable sealants are (1) a 60:40 mixture ofmicrocrystalline wax and refine
20、d crystalline parafin wax, ( 2) tissueembedding wax, and (3) a 50:50 mixture of beeswax and rosin.7. Test Specimen7.1 Suggested cementitious substrates to be used should be75 by 150 by 15 mm (3 by 6 by916 in.) as outlined in PracticeD1734. Before use, the substrates should be removed fromstorage in
21、water, dried at 80 6 5C (176 6 9F) until a constantweight has been reached. A constant weight shall be assumedwhen the specimen weighed to the nearest 0.1 g loses not morethan 0.1 % in any 4-h period. Allow specimens to cool andstore at standard conditions as outlined in Specification D3924before us
22、e.7.2 Apply treatment to one face of the test substrates usingone of the methods described in Practices D823 or by brushfollowing manufacturers application instructions. The amountof material (spreading rate) applied to the substrate must thenbe calculated and reported.7.3 Air-dry the treated substr
23、ate in a horizontal position for7 days in a room preferably maintained at 23 6 2C (73.5 63.5F) and 50 6 5 % relative humidity as outlined in Specifi-cation D3924. The drying schedule may be modified asrecommended by manufacturer.8. Procedure8.1 Prepare at least three test assemblies for each testmat
24、erial as follows:8.1.1 Fill the assembly with water to within 20 6 5mm(0.8 6 0.2 in. ) of the treated substrate.8.1.2 Seal the treated substrate to the top edge of theassembly with wax or sealant with the treated face placedfacing the water.8.2 Weigh the test assemblies to 0.1 g. and place them in t
25、hetest chamber. Record time, temperature, and relative humidity.Unless other conditions are agreed upon between the purchaserand the seller, perform the test(s) in a chamber maintained at 236 2C (73 6 3.5F) and 50 6 5 % relative humidity.8.2.1 In general, the test assemblies should be weighedevery 2
26、4 h for a period of time until the weight change per 24h has become consistent. The time that weighings are takenshould be recorded to the precision of approximately 1 % ofthe time span between weighings. Thus, if weighings are madeevery day, a time to the nearest 15 min would be allowed.8.2.2 Treat
27、ments expected to have high WVT ratings, over6.7 metric perms (10 perms), may require weighings morefrequently than once a day.8.3 Return the test assemblies to the test chamber immedi-ately after weighings.9. Calculation9.1 For each material tested, plot the weight changes againstelapsed time. When
28、 a straight line adequately fits the plot of atleast four properly spaced points, a nominal steady state existsand the slope of the straight line is the rate of water vaportransmission.9.2 Calculate one or more of the following, depending of thewater vapor transmission characteristics to be determin
29、ed:9.2.1 Calculate the water vapor transmission rate, WVT:9.2.1.1 In inch-pound units as follows:WVT 5 G/t!/A 5 grains per square foot per 1 h (1)where:G = weight change, grains (from the straight line),t = time during which G occurred, h,A = test area, square foot, and1 g = 15.43 grains.9.2.1.2 In
30、metric units as follows:TABLE 1 Saturation Vapor PressureTemperature PressureF C in. Hg mm Hg72.3 22.4 0.800 20.31672.5 22.5 0.805 20.44072.7 22.6 0.810 20.56572.9 22.7 0.816 20.69073.1 22.8 0.819 20.81573.3 22.9 0.824 20.94173.4 23.0 0.829 21.06873.6 23.1 0.834 21.19673.8 23.2 0.840 21.32474.0 23.3
31、 0.845 21.45374.2 23.4 0.850 21.58374.4 23.5 0.855 21.71474.5 23.6 0.860 21.84599.3 37.4 1.894 48.10299.5 37.5 1.904 48.36499.7 37.6 1.914 48.62799.9 37.7 1.925 48.891100.1 37.8 1.935 49.157100.2 37.9 1.946 49.424100.4 38.0 1.956 49.692100.6 38.1 1.967 49.961100.8 38.2 1.978 50.231101.0 38.3 1.988 5
32、0.502101.1 38.4 1.999 50.774101.3 38.5 2.010 51.048101.5 38.6 2.021 51.323D6490 99 (2014)2WVT 5 G/t!/A 5 grams per square metre per 24 h (2)where:G = weight change, grams (from the straight line),t = time during which G occurred, h, andA = test area, square metre.9.2.2 Calculate the permeance, WVP:9
33、.2.2.1 In inch-pound units as follows:WVP 5 WVT/p 5 grains per ft2per 1 h per inch of mercury perms!(3)where:p =S(R1R2),S = inches of mercury (saturation vapor pressure at testtemperature) see Table 1,R1= relative humidity at vapor source, andR2= relative humidity at vapor sink.9.2.2.2 In metric uni
34、ts as follows:WVP 5 WVT/p 5 grams per square metre per 24 h per (4)millimetre of mercury, metric perms!where:p = S (R1 R2),S = millimetres of mercury (saturation vapor pressure attest temperature) see Table 1,R1= relative humidity at vapor source, andR2= relative humidity at vapor sink.10. Report10.
35、1 Report the following information:10.1.1 Method of application and curing procedure used.10.1.2 Spreading rate applied or mean film thickness of thetest specimens for each material.10.1.3 Substrate, if different than specified in SpecificationD1734.10.1.4 Test temperature and relative humidity in t
36、he testchamber.10.1.5 Computed rate of water vapor transmission (WVT),either in inch-pound or in metric units.10.1.6 The computed permeance in terms of both perms andmetric units.11. Precision and Bias11.1 Precision is being developed in Subcommittee D01.47.11.2 Bias is not applicable to this test m
37、ethod.12. Keywords12.1 permeability; permeance; perms; water vapor per-meance; water vapor transmissionASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that d
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