1、Designation: D5886 95 (Reapproved 2011)Standard Guide forSelection of Test Methods to Determine Rate of FluidPermeation Through Geomembranes for SpecificApplications1This standard is issued under the fixed designation D5886; the number immediately following the designation indicates the year oforigi
2、nal adoption or, in the 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 guide covers selecting one or more appropriate testmethods
3、to assess the permeability of all candidate geomem-branes for a proposed specific application to various per-meants. The widely different uses of geomembranes as barriersto the transport and migration of different gases, vapors, andliquids under different service conditions require determina-tions o
4、f permeability by test methods that relate to and simulatethe service. Geomembranes are nonporous homogeneous ma-terials that are permeable in varying degrees to gases, vapors,and liquids on a molecular scale in a three-step process (1)bydissolution in or absorption by the geomembrane on theupstream
5、 side, (2) diffusion through the geomembrane, and (3)desorption on the downstream side of the barrier.1.2 The rate of transmission of a given chemical species,whether as a single permeant or in mixtures, is driven by itschemical potential or in practical terms by its concentrationgradient across the
6、 geomembrane. Various methods to assessthe permeability of geomembranes to single component per-meants, such as individual gases, vapors, and liquids arereferenced and briefly described.1.3 Various test methods for the measurement of permeationand transmission through geomembranes of individual spec
7、iesin complex mixtures such as waste liquids are discussed.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-bi
8、lity of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D471 Test Method for Rubber PropertyEffect of LiquidsD814 Test Method for Rubber PropertyVapor Transmis-sion of Volatile LiquidsD815 Method of Testing Coated Fabrics Hydrogen Per-meance3D1434 Test Method for Deter
9、mining Gas PermeabilityCharacteristics of Plastic Film and SheetingD4439 Terminology for GeosyntheticsD4491 Test Methods for Water Permeability of Geotextilesby PermittivityE96/E96M Test Methods for Water Vapor Transmission ofMaterialsF372 Test Method for Water Vapor Transmission Rate ofFlexible Bar
10、rier Materials Using an Infrared DetectionTechnique3F739 Test Method for Permeation of Liquids and Gasesthrough Protective Clothing Materials under Conditions ofContinuous Contact3. Terminology3.1 Definitions:3.1.1 downstream, nthe space adjacent to the geomem-brane through which the permeant is flo
11、wing.3.1.2 geomembrane, nan essentially impermeable geo-synthetic composed of one or more synthetic sheets. (SeeTerminology D4439.)3.1.2.1 DiscussionIn geotechnical engineering, essen-tially impermeable means that no measurable liquid flowsthrough a geosynthetic when tested in accordance with TestMe
12、thods D4491.3.1.3 geosynthetic, na planar product manufactured frompolymeric material used with soil, rock, earth, or other geo-technical engineering-related material as an integral part of aman-made project, structure, or system. (See TerminologyD4439.)3.1.4 permeability, nthe rate of flow under a
13、differentialpressure, temperature, or concentration of a gas, liquid, orvapor through a material. (Modified from Test MethodsD4491.)1This guide is under the jurisdiction ofASTM Committee D35 on Geosyntheticsand is the direct responsibility of Subcommittee D35.10 on Geomembranes.Current edition appro
14、ved June 1, 2011. Published July 2011. Originally approvedin 1995. Last previous edition approved in 2006 as D5886 95 (2006). DOI:10.1520/D5886-95R11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStand
15、ards volume information, refer to the standards Document Summary page onthe ASTM website.3Withdrawn. The last approved version of this historical standard is referencedon www.astm.org.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.3
16、.1.5 permeant, na chemical species, gas, liquid, or vaporthat can pass through a substance.4. Summary of Guide4.1 The wide range of uses of geomembranes as barriers inmany different environments to many different permeatingspecies requires different test procedures to assess the effec-tiveness of a
17、given membrane for a given application. Thepermeating species range from a single component to highlycomplex mixtures such as those found in waste liquids andleachates. In specialized applications, service it may be impor-tant to measure transmission or migration of a species thatwould take place un
18、der specific conditions and environmentsincluding temperature, vapor pressure, and concentration gra-dients. Tests that would be applicable to the measurement ofthe permeability of a material to different permeants present invarious applications are summarized in Table 1.4.1.1 In the use of geomembr
19、anes in service as barriers tothe transmission of fluids, it is essential to recognize thedifference between geomembranes that are nonporous homo-geneous materials and other liner materials that are porous,such as soils and concretes. The transmission of permeatingspecies through geomembranes withou
20、t holes proceeds byabsorption of the species in the geomembrane and diffusionthrough the geomembrane on a molecular basis. The drivingforce is chemical potential across the geomembrane. A liquidpermeates porous materials in a condensed state that can carrythe dissolved constituents, and the driving
21、force for suchpermeation is hydraulic pressure. Due to the selective nature ofgeomembranes, the permeation of the dissolved constituents inliquids can vary greatly, that is, components of a mixture canpermeate at different rates due to differences in solubility anddiffusibility in a given geomembran
22、e. With respect to theinorganic aqueous salt solution, the geomembranes are semi-permeable, that is, the water can be transmitted through thegeomembranes, but the ions are not transmitted. Thus, thewater that is transmitted through a hole-free geomembranedoes not carry dissolved inorganics. The dire
23、ction of perme-ation of a component in the mixture is determined thermody-namically by its chemical potential difference or concentrationgradient across the geomembrane. Thus the water in thewastewater on the upstream side is at a lower potential than theless contaminated water on the downstream sid
24、e and canpermeate the geomembrane into the wastewater by osmosis.4.1.2 Although inorganic salts do not permeate geomem-branes, some organic species do. The rate of permeationthrough a geomembrane depends on the solubility of theorganic in the geomembrane and the diffusibility of the organicin the ge
25、omembrane as driven by the chemical potentialgradient. Principle factors that can affect the diffusion of anorganic within a geomembrane include:4.1.2.1 The solubility of the permeant in the geomembrane,4.1.2.2 The microstructure of the polymer, for example,percent crystallinity,4.1.2.3 Whether the
26、condition at which diffusion is takingplace is above or below the glass transition temperature of thepolymer,4.1.2.4 The other constituents in the geomembrane com-pound,4.1.2.5 Variation in manufacturing processes,4.1.2.6 The flexibility of the polymer chains,4.1.2.7 The size and shape of the diffus
27、ing molecules,4.1.2.8 The temperature at which diffusion is taking place,and4.1.2.9 The geomembrane.4.1.3 The movement through a hole-free geomembrane ofmobile species that would be encountered in service would beaffected by many factors, such as:4.1.3.1 The composition of the geomembrane with respe
28、ctto the polymer and to the compound,TABLE 1 Applicable Test Method for Measuring Permeability of Geomembranes to Various PermeantsFluid Being Contained Example of Permeant Example of Field ApplicationApplicable Test Method and PermeantDetector and QuantifierSingle-Component Fluids:Gas H2,O2Barriers
29、, pipe, and hose liners D815N2,CH4D1434-VCO2D1434-PWater vapor H2O Moisture vapor barriers, water reservoircoversE96/E96M, D653Liquid water H2O Liners for reservoirs, dams, and canals Soil-type permeameter with hydraulicpressureOrganic vapor Organic species Secondary containment for organicsolvent a
30、nd gasolineD814, E96/E96M, F372Organic liquid Organic solvents species Containers, tank liners secondarycontainmentD814, E96/E96MMulticomponents Fluids:Gases CO2/CH4Barriers, separation of gases F372, GC, GCMSAqueous solutions of inorganic, forexample, brines, incinerator ashleachates, leach pad lea
31、chateIons, salts Pond liners Pouch, osmotic cell, ion analysisMixtures of organics, spills,hydrocarbon fuelsOrganic species Liners for tanks and secondarycontainmentE96/E96M with headspace, GCAqueous solutions of organics Organic species, H2O Liners for ponds and waste disposal Pouch, Multi-compartm
32、ent cell withanalysis by GC on GCMSComplex aqueous solutions of organicsand inorganic speciesH2O, organic species, dissolved salts Liners for waste disposal Pouch, Multi-compartment cell, osmoticcell, analysis by head-space GCD5886 95 (2011)24.1.3.2 The thickness of the geomembrane,4.1.3.3 The servi
33、ce temperature,4.1.3.4 The temperature gradient across the geomembranein service,4.1.3.5 The chemical potential across the geomembrane,that includes pressure and concentration gradient,4.1.3.6 The composition of the fluid and the mobile con-stituents,4.1.3.7 The solubility of various components of a
34、n organicliquid in the particular geomembrane that increase concentra-tion of individual components on the upstream side of thegeomembrane and can cause swelling of the geomembraneresulting in increased permeability,4.1.3.8 The ion concentration of the liquid, and4.1.3.9 Ability of the species to mo
35、ve away from the surfaceon the downstream side.4.1.4 Because of the great number of variables, it is impor-tant to perform permeability tests of a geomembrane underconditions that simulate as closely as possible the actualenvironmental conditions in which the geomembrane will be inservice.5. Signifi
36、cance and Uses5.1 The principal characteristic of geomembranes is theirintrinsically low permeability to a broad range of gases, vapors,and liquids, both as single-component fluids and as complexmixtures of many constituents. As low permeable materials,geomembranes are being used in a wide range of
37、engineeringapplications in geotechnical, environmental, and transportationareas as barriers to control the migration of mobile fluids andtheir constituents. The range of potential permeants is broadand the service conditions can differ greatly. This guide showsusers test methods available for determ
38、ining the permeabilityof geomembranes to various permeants.5.2 The transmission of various species through a geomem-brane is subject to many factors that must be assessed in orderto be able to predict its effectiveness for a specific service.Permeability measurements are affected by test conditions,
39、 andmeasurements made by one method cannot be translated fromone application to another.Awide variety of permeability testshave been devised to measure the permeability of polymericmaterials; however, only a limited number of these procedureshave been applied to geomembranes. Test conditions andproc
40、edures should be selected to reflect actual service require-ments as closely as possible. It should be noted that fieldconditions may be difficult to model or maintain in thelaboratory.This may impact apparent performance of geomem-brane samples.5.3 This guide discusses the mechanism of permeation o
41、fmobile chemical species through geomembranes and the per-meability tests that are relevant to various types of applicationsand permeating species. Specific tests for the permeability ofgeomembranes to both single-component fluids and multicom-ponent fluids that contain a variety of permeants are de
42、scribedand discussed.6. Basis of Classification6.1 Even though geomembranes are nonporous and cannotbe permeated by liquids as such, gases and vapors of liquidscan permeate a geomembrane on a molecular level. Thus, evenif a geomembrane is free of macroscopic holes, some compo-nents of the contained
43、fluid can permeate and might escape thecontainment unit.6.2 The basic mechanism of permeation through geomem-branes is essentially the same for all permeating species. Themechanism differs from that through porous media, such assoils and concrete, which contain voids that are connected insuch a way
44、that a fluid introduced on one side will flow fromvoid to void and emerge on the other side; thus, a liquid canflow through the voids and carry dissolved species.6.3 Overall rate of flow through saturated porous mediafollows Darcys equation that states that the flow rate isproportional to the hydrau
45、lic gradient, as is shown in thefollowing equation:Q 5 kiA (1)where:Q = rate of flow,k = constant (Darcys coefficient of permeability),A = total inside cross-sectional area of the sample con-tainer, andi = hydraulic gradient.6.4 With most liquids in saturated media, the flow followsDarcys equation;
46、however, the flow can deviate due tointeractions between the liquid and the surface of the soilparticles. These interactions become important in the escape ofdissolved species through a low-permeability porous linersystem in a waste facility. Dissolved chemical species, eitherorganic or inorganic, n
47、ot only can permeate such a mediumadvectively (that is, the liquid acts as the carrier of thechemical species), but also by diffusion in accordance withFicks two laws of diffusion.6.5 Even though polymeric geomembranes are manufac-tured as solid homogeneous nonporous materials, they containinterstit
48、ial spaces between the polymer molecules throughwhich small molecules can diffuse. Thus, all polymericgeomembranes are permeable to a degree.Apermeant migratesthrough the geomembrane on a molecular basis by an activateddiffusion process and not as a liquid. This transport process ofchemical species
49、involves three steps:6.5.1 The solution or absorption of the permeant at theupstream surface of the geomembrane,6.5.2 Diffusion of the dissolved species through thegeomembrane, and6.5.3 Evaporation or desorption of the permeant at thedownstream surface of the geomembrane.6.6 The driving force for this type of activated permeationprocess is the “activity” or chemical potential of the permeantthat is analogous to mechanical potential and electrical poten-tial in other systems. The chemical potential of the permeantdecreases continuously in the direction of the permeation.C
