ASTM C1498-2004a(2016) Standard Test Method for Hygroscopic Sorption Isotherms of Building Materials《建筑材料吸湿吸着等温线的标准试验方法》.pdf
《ASTM C1498-2004a(2016) Standard Test Method for Hygroscopic Sorption Isotherms of Building Materials《建筑材料吸湿吸着等温线的标准试验方法》.pdf》由会员分享,可在线阅读,更多相关《ASTM C1498-2004a(2016) Standard Test Method for Hygroscopic Sorption Isotherms of Building Materials《建筑材料吸湿吸着等温线的标准试验方法》.pdf(4页珍藏版)》请在麦多课文档分享上搜索。
1、Designation: C1498 04a (Reapproved 2016)Standard Test Method forHygroscopic Sorption Isotherms of Building Materials1This standard is issued under the fixed designation C1498; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the yea
2、r 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 specifies a laboratory procedure for thedetermination of hygroscopic sorption isotherms of any c
3、on-struction materials. The method was originally developed forthe ASTM Thermal Insulation committee.1.2 For material characterization, the primary emphasis ison the adsorption isotherm (that is, sorption isotherm thatdescribes the wetting process of the material from the oven-drycondition).1.3 Dete
4、rmination of desorption isotherm, (that is, sorptionisotherm that describes the drying process of a material fromthe state of absolute saturation with water) is performed wheninformation on drying characteristics of construction materialsis required. Typically both adsorption and desorption isotherm
5、sare required for the purpose of hygrothermal models.1.4 The values stated in SI units are to be regarded asstandard. No other units of measurement are included in thisstandard.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsi
6、bility 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 Documents2.1 ASTM Standards:2E104 Practice for Maintaining Constant Relative Humidityby Means of Aqueous SolutionsE337 Test
7、Method for Measuring Humidity with a Psy-chrometer (the Measurement of Wet- and Dry-Bulb Tem-peratures)3. Terminology3.1 Definitions of Terms Specific to This Standard:3.1.1 adsorption isothermthe sorption isotherm measuredexclusively during the hygroscopic adsorption process startedfrom the oven-dr
8、y condition.3.1.2 desorption isothermthe sorption isotherm measuredexclusively during the hygroscopic desorption process startedfrom the condition of full water saturation of the material.3.1.3 hygroscopic adsorptionfixation of water moleculesfrom ambient air on surfaces of a material until equilibr
9、ium isestablished.3.1.4 hygroscopic desorptionrelease of adsorbed watermolecules from surfaces of a material into the ambient air untilequilibrium is established.3.1.5 hysteresisa physical phenomenon which makes thedesorption isotherm different from the adsorption isotherm dueto the difference in th
10、e energy level of pore water.3.1.6 moisture content, by massmass of water retained inthe specimen divided by the dry mass of the specimen.3.1.7 moisture content, by volumevolume of water re-tained in the specimen divided by the volume of the dryspecimen.3.1.8 sorption isothermrelationship between th
11、e relativehumidity (RH) (see Test Method E337) and the equilibriummoisture content of the material, at a specified temperature.4. Significance and Use4.1 The purpose of these tests is to obtain, for a specifiedtemperature, by means of a specified laboratory procedure, thevalues of the equilibrium mo
12、isture content at various levels ofRH. These values are used either as means to characterize thematerial or as material characteristics needed as input toappropriate computer models that can simulate wetting ordrying potential of individual building materials or materialassemblies under specified en
13、vironmental conditions.4.2 A specified value of the equilibrium moisture contentcan also be used for material characterization. If this type ofmaterial characterization is called for in a material specification(for example, mineral or cellulose fiber insulation), the equi-librium at 95 6 3 %RH shall
14、 be used.1This test method is under the jurisdiction ofASTM Committee C16 on ThermalInsulation and is the direct responsibility of Subcommittee C16.33 on InsulationFinishes and Moisture.Current edition approved Aug. 15, 2016. Published August 2016. Originallyapproved in 2001. Last previous edition a
15、pproved in 2010 as C1498 04a (2010)1.DOI: 10.1520/C1498-04AR16.2For 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 websit
16、e.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14.3 For ease and repeatability of measurements, the mea-surements for characterization are performed on adsorptionisotherms. Though desorption is the reverse of adsorption,most porous
17、materials reach different equilibrium levels duringthese two processes. Usually, the equilibrium moisture contenton the desorption isotherm is higher than that on the adsorptionisotherm for the same level of RH.5. Apparatus5.1 Weighing CupsWeighing cups, made from non-absorbing material3, for exampl
18、e, glass, shall be provided withtight-fitting lids and the volume shall not be less than 15 cm3.5.2 BalanceAn analytical balance capable of weighing thecups within 1 mg shall be used. The accuracy of the balanceshall be at least 6 0.1 percent of the total specimen weight.5.3 Drying OvenA ventilated
19、drying oven, capable ofmaintaining the required drying temperature within 62K fortemperatures less than 75C and 64K for temperatures above75C, and a relative humidity of less than 10 %, shall be used.In warm-humid laboratory environment or at low dryingtemperatures, it will be necessary to provide a
20、 supply of driedair to achieve the less than 10 % relative humidity specificationin the drying oven.5.4 Environment ChamberThe specimens shall be ex-posed to controlled environmental conditions. The precisecondition for the test environment shall be maintained in one ofthe following two ways, (a) wi
21、th desiccators placed in a roomwith controlled temperature , or (b) with a climatic chamber.5.4.1 The test conditions can be generated within thedesiccators that contain saturated salt solutions4, (see alsoPractice E104). Since the partial pressure of the vapor abovethe solution is strongly dependen
22、t on the temperature stability,temperature oscillation in the desiccator should be as small aspossible. The range 60.1K is recommended. The maximumvariation permitted by this standard shall not exceed 60.5K.Normally, the desiccators are placed inside a chamber or aroom with controlled temperature. I
23、n this case, it is recom-mended that the chamber or room is capable of maintaining thetest conditions within 61K.5.4.2 If the climatic chamber is used for the determinationof the hygroscopic sorption isotherms, the chamber shall becapable of maintaining the test conditions within 63 % for thefull ra
24、nge of RH.5Temperature shall be maintained within60.5K.5.5 Desiccator, with (a) calcium chloride as desiccant fordrying, or (b) with saturated salt solution to generate specificrelative humidity level.6. Test Specimens6.1 A test specimen shall have a mass of at least 10 g. Thetest specimen may be cu
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