1、Designation:C169909(Reapproved 2015)Standard Test Method forMoisture Retention Curves of Porous Building MaterialsUsing Pressure Plates1This standard is issued under the fixed designation C1699;the number immediately following the designation indicates the year oforiginal adoption or,in the case of
2、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 specifies a laboratory procedure for thedetermination of the water retention curve(or
3、 moisture storagecapacity)of porous building materials at very high relativehumidity(RH)levels(95 to 100%RH)corresponding to thecapillary moisture region of the sorption isotherm.This isachieved by using the pressure plate test apparatus.Thistechnique was originally developed to study soil moisturec
4、ontent and eventually had been adapted to building construc-tion materials.1.2 At higher RH levels(95 to 100%RH)of the sorptionisotherm(see Test Method C1498),use of climatic chamber isnot an option.This technique uses overpressure to extractwater out of the pore structure of porous materials untile
5、quilibrium between the moisture content in the specimens andthe corresponding overpressure is achieved.Using the pressureplate extractors,equilibrium can only be reached by desorp-tion.1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thiss
6、tandard.1.4 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.Referenc
7、ed Documents2.1 ASTM Standards:2C1498 Test Method for Hygroscopic Sorption Isotherms ofBuilding MaterialsD2325 Test Method for Capillary-Moisture Relationshipsfor Coarse-and Medium-Textured Soils by Porous-PlateApparatus(Withdrawn 2007)3D3152 Test Method for Capillary-Moisture Relationshipsfor Fine-
8、Textured Soils by Pressure-Membrane Apparatus(Withdrawn 2007)3E337 Test Method for Measuring Humidity with a Psy-chrometer(the Measurement of Wet-and Dry-Bulb Tem-peratures)3.Terminology3.1 Definitions of Terms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 desorption isothermthe sorption isotherm measuredexclusiv
9、ely during the hygroscopic desorption process startedfrom the condition of full water saturation of the material.3.1.2 sorption isothermrelationship between the relativehumidity(see Test Method E337)and the equilibrium moisturecontent of the material,at a specified temperature.3.1.3 pressure-plate f
10、acilityHeavy steel vessel capable ofholding different pressure levels.3.1.4 moisture content,by massmass of water retained inthe specimen divided by the dry mass of the specimen.4.Significance and Use4.1 The purpose of this test is to obtain,by means of aspecified laboratory procedure,the values of
11、the equilibriummoisture content at higher RH levels(95 to 100%).Thesevalues are used either as means to characterize the material oras material characteristics needed as input to appropriatecomputer models that can simulate wetting or drying potentialof individual building materials or material asse
12、mblies underspecified environmental conditions.5.Apparatus5.1Pressure vesselHeavy-duty steel vessels of approxi-mately 305 mm in diameter and about 75 mm or 250 mm highwith heavy top lid tightly-held against O-ring gasket byclamping bolts(see Fig.1).1This test method is under the jurisdiction ofASTM
13、 Committee C16 on ThermalInsulation and is the direct responsibility of Subcommittee C16.33 on InsulationFinishes and Moisture.Current edition approved May 1,2015.Published August 2015.Originallyapproved in 2008.Last previous edition approved in 2009 as C169909.DOI:10.1520/C1699-09R15.2For reference
14、d 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.3The last approved version of this historical standard is referenced onwww.astm.
15、org.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 5.2 Porous ceramic platesThis is the plate upon which thespecimens sit and is composed of microscopic pores allowingonly water to flow through it.The plate assembly is exposed toan overp
16、ressure that can be adjusted,while the other side of theplate is always at atmospheric pressure resulting in a pressuredifference over the plate and the specimens.5.3 BalanceAn analytical balance capable of weighingwithin 1 mg shall be used.The accuracy of the balance shall beat least 6 0.1 percent of the total specimen weight.5.4 Drying ovenA ventilated drying oven,capable ofmaintaining the required drying temperature within 62K fortemperatures less than 75C and 64K for temperatures above75C,an