1、Designation: D 5886 95 (Reapproved 2006)Standard Guide forSelection of Test Methods to Determine Rate of FluidPermeation Through Geomembranes for SpecificApplications1This standard is issued under the fixed designation D 5886; the number immediately following the designation indicates the year ofori
2、ginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide covers selecting one or more appropriate testmetho
3、ds 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-tion
4、s of 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 theupstr
5、eam 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
6、the 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 s
7、peciesin 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
8、-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 471 Test Method for Rubber PropertyEffect of LiquidsD 814 Test Method for Rubber PropertyVapor Transmis-sion of Volatile LiquidsD 815 Method of Testing Coated Fabrics Hydrogen Per-meance3D 1434 Test Method fo
9、r Determining Gas PermeabilityCharacteristics of Plastic Film and SheetingD 4439 Terminology for GeosyntheticsD 4491 Test Methods for Water Permeability of Geotextilesby PermittivityE 96/E 96M Test Methods for Water Vapor Transmission ofMaterialsF 372 Test Method for Water Vapor Transmission Rate of
10、Flexible Barrier Materials Using an Infrared DetectionTechniqueF 739 Test Method for Resistance of Protective ClothingMaterials to Permeation by Liquids or Gases Under Con-ditions of Continuous Contact3. Terminology3.1 Definitions:3.1.1 downstream, nthe space adjacent to the geomem-brane through whi
11、ch the permeant is flowing.3.1.2 geomembrane, nan essentially impermeable geo-synthetic composed of one or more synthetic sheets. (SeeTerminology D 4439.)3.1.2.1 DiscussionIn geotechnical engineering, essen-tially impermeable means that no measurable liquid flowsthrough a geosynthetic when tested in
12、 accordance with TestMethods D 4491.3.1.3 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 TerminologyD 4439.)3.1.4 permeability, n
13、the rate of flow under a differentialpressure, temperature, or concentration of a gas, liquid, orvapor through a material. (Modified from Test MethodsD 4491.)3.1.5 permeant, na chemical species, gas, liquid, or vaporthat can pass through a substance.1This guide is under the jurisdiction ofASTM Commi
14、ttee D35 on Geosyntheticsand is the direct responsibility of Subcommittee D35.10 on Geomembranes.Current edition approved June 1, 2006. Published June 2006. Originallyapproved in 1995. Last previous edition approved in 2001 as D 5886 95 (2001).2For referenced ASTM standards, visit the ASTM website,
15、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.3Withdrawn.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, Unite
16、d States.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 given membrane for a given application. Thepermeating species range from a single
17、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 under specific conditions and environmentsincluding temperature, vapor pressure, and
18、 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 geomembranes in service as barriers tothe transmission of fluids, it is essential to recog
19、nize 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 without holes proceeds byabsorption of the species in the geomembrane and diffusionthrou
20、gh 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 force for suchpermeation is hydraulic pressure. Due to the selective nature ofgeom
21、embranes, 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 geomembrane. With respect to theinorganic aqueous salt solution, the geomembranes are semi-p
22、ermeable, 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 direction of perme-ation of a component in the mixture is determined thermody-namicall
23、y 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 side and canpermeate the geomembrane into the wastewater by osmosis.4.1.2 Although in
24、organic 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 geomembrane as driven by the chemical potentialgradient. Principle factors that can
25、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 condition at which diffusion is takingplace is above or below the glass transition
26、 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 diffusing molecules,4.1.2.8 The temperature at which diffusion is taking place,and4.1.2.
27、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 respectto the polymer and to the compound,4.1.3.2 The thickness of the geomembrane,4.1.
28、3.3 The service temperature,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, pipe, a
29、nd hose liners D 815N2,CH4D 1434-VCO2D 1434-PWater vapor H2O Moisture vapor barriers, water reservoircoversE 96/E 96M, D653Liquid water H2O Liners for reservoirs, dams, and canals Soil-type permeameter with hydraulicpressureOrganic vapor Organic species Secondary containment for organicsolvent and g
30、asolineD 814, E 96/E 96M, F 372Organic liquid Organic solvents species Containers, tank liners secondarycontainmentD 814, E 96/E 96MMulticomponents Fluids:Gases CO2/CH4Barriers, separation of gases F 372, GC, GCMSAqueous solutions of inorganic, forexample, brines, incinerator ashleachates, leach pad
31、 leachateIons, salts Pond liners Pouch, osmotic cell, ion analysisMixtures of organics, spills,hydrocarbon fuelsOrganic species Liners for tanks and secondarycontainmentE 96/E 96M with headspace, GCAqueous solutions of organics Organic species, H2O Liners for ponds and waste disposal Pouch, Multi-co
32、mpartment 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 GCD 5886 95 (2006)24.1.3.4 The temperature gradient across the geomemb
33、ranein 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 an organicliquid in the particular geomembrane that increase concen
34、tra-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 move away from the surfaceon the downstream side.4.1.4 Because of th
35、e 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. Significance and Uses5.1 The principal characteristic of geomembranes is
36、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 engineeringapplications in geotechnical, environmental, and transp
37、ortationareas 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 determining the permeabilityof geomembranes to various permeants.5.2 The
38、 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, andmeasurements made by one method cannot be translated fromone a
39、pplication 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 andprocedures should be selected to reflect actual service require-ments
40、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 ofmobile chemical species through geomembranes and the per-meabilit
41、y 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 describedand discussed.6. Basis of Classification6.1 Even though geo
42、membranes 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 fluid can permeate and might escape thecontainment unit.6.2 The ba
43、sic 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 that a fluid introduced on one side will flow fromvoid to void and
44、 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 hydraulic gradient, as is shown in thefollowing equation:Q 5 kiA (1)wher
45、e: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; however, the flow can deviate due tointeractions between the liqui
46、d 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, not only can permeate such a mediumadvectively (that is, the liquid
47、 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 containinterstitial spaces between the polymer molecules throughwhich small molecu
48、les 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 involves three steps:6.5.1 The solution or absorption of the perme
49、ant 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.Concentration is often used as a practical measure of thechemical po
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