ASTM D6539-2000(2006)e2 用流动空气测定局部饱水孔隙材料气动渗透性的标准试验方法

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【英文标准名称】:StandardTestMethodforMeasurementofPneumaticPermeabilityofPartiallySaturatedPorousMaterialsbyFlowingAir
【原文标准名称】:用流动空气测定局部饱水孔隙材料气动渗透性的标准试验方法
【标准号】:ASTMD6539-2000(2006)e2
【标准状态】:现行
【国别】:美国
【发布日期】:2000
【实施或试行日期】:
【发布单位】:美国材料与试验协会(US-ASTM)
【起草单位】:D18.04
【标准类型】:(TestMethod)
【标准水平】:()
【中文主题词】:
【英文主题词】:airflow;flexiblewallpermeameter;permeability;permeameter;pneumaticpermeability;rigidwallpermeameter;Flowingairtest;Partially-saturatedporousmaterials;Pneumaticpermeability;Porousmedia/materials
【摘要】:Thistestmethodappliestotheone-dimensionallaminar(viscous)flowofairinporousmaterialssuchassoil.Note18212;Thistestmethoddealswithporousmaterialswithbothgaseous(air)andliquid(porewater)mobilefluids:Theliquidphaseismuchlesscompressible,hasahigherviscosity,andismuchmoretightlyboundtothesolidphasebychemicalforces.Theassumptionofsingle-phaseflowmaystillbepresumedtobevalidsincethetestgradientensuringtheconditionsoflaminarflowmaybelowenoughthatflowoftheliquidphaseisnegligible.Thedegreeofsaturationofthespecimenshallbelessthanthatwhichwouldproducesignificantinternaltransportofporewateroralterthecontinuityofairvoidsundertheappliedpneumaticgradients.Themaximumpermissibledegreeofsaturationmustbeevaluatedbyanexperiencedanalyst.Innoinstanceshallthespecimenbesosaturatedthatporewaterappearsattheexitofthepermeametercellduringthetest.Thistestmethodisbasedontheassumptionthattherateofmassflowthroughthespecimenisconstantwithtime.Note28212;Whenaspecimencontainsvolatilematerialsthisassumptionisviolated.Themassofgasflowingoutwillbegreaterthanthatflowingin,thepneumaticgradientisindeterminateandthetestmaybecomemeaningless.Suchspecimensposespecialproblemsandmustbedecontaminatedbeforeanalysisinordertominimizehealthandsafetyconcernsandtopreventcontaminationofthetestapparatus.Thepneumaticpermeabilityofporousmaterialsmaybestronglydependentonavarietyofphysicalpropertiesincludingthevoidratio,thedegreeofsaturation,percentanddirectionofcompaction,andsoforth.Itisbeyondthescopeofthistestmethodtoelaboratethesedependencies.Rather,thistestmethodisintendedtobeameasurementtechniquefordeterminingthepneumaticpermeabilityunderacertainsetoflaboratoryconditions.Itistheresponsibilityoftherequestortospecifywhichsoilparametersmustbecontrolledtoensureavalidextensionofthetestresultstofieldconditions.ItisassumedthatDarcy''sLawisvalid.ThevalidityofDarcy''slawmaybeevaluatedbyplottingthevolumetricflowthroughthespecimenagainstthedifferentialpressuredropacrossthespecimen.Iftheindividualtestpointsliewithin25%ofastraightlinepassingthroughtheorigin,thenDarcy''slawmaybetakenasvalid.Note38212;Darcy''slawisvalidonlywhensaturationdoesnotchangeovertime.Longmeasurementtimesassociatedwiththeuseofbubblemetersandmanometersmayindirectlybeanuncontrolledsourceofvariabilitywhenplottingflowversuspressuredrop(see8.2).Therecommendeduseofdigitalelectronicflowandpressuresensorsleadstoconsiderablyreducedmeasurementtimesbecausetheusercanquicklydeterminebyinspectionwhenasteadystateconditionhasbeenreached.Atthatpointonlyasinglereadingneedstobetakenforareliablemeasurement.Arapidcourseofmeasurementwillminimizedehydrationofpartiallysaturatedspecimens.Note48212;Humidifyingthetestgastominimizespecimendehydrationisnotrecommendedbecause:(1)thereisnopracticalwaytoeithermeasureorcontroltherelativehumidityofthetestgas,eitherattheinletoroutletofthespecimen;(2)thecalibrationoftheelectronicflowmeterisfordryaironlyandwouldbecomeunreliableinthepresenceofwatervapor,especiallyinviewofthepotentialforirreversibleadsorptionofmoistureonthesensorelements;(3)thereisadangerofpermanentwatercondensationinthestatictransfer..........
【中国标准分类号】:P13
【国际标准分类号】:13_080_20
【页数】:10P.;A4
【正文语种】:英语