1、Designation: D6766 12Standard Test Method forEvaluation of Hydraulic Properties of Geosynthetic ClayLiners Permeated with Potentially Incompatible AqueousSolutions1This standard is issued under the fixed designation D6766; the number immediately following the designation indicates the year oforigina
2、l 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 test method covers laboratory measurement of bothflux and hyd
3、raulic conductivity (also referred to as coeffcientof permeability) of geosynthetic clay liner (GCL) specimenspermeated with chemical solutions and leachates utilizing aflexible wall permeameter. For test measurement of indexhydraulic properties of geosynthetic clay liners, refer to TestMethod D5887
4、.1.2 This test method may be utilized with GCL specimensthat have a hydraulic conductivity less than or equal to 1 10-5 m/s (1 10-3cm/s).1.3 This test method is applicable to GCL products havinggeotextile backing(s). It is not applicable to GCLproducts withgeomembrane backing(s), geofilm backing(s)
5、or polymer coat-ing backing(s).1.4 This test method provides measurements of flux andhydraulic conductivity under a prescribed set of conditions, asan index test, that can be used for manufacturing qualitycontrol. The flux and hydraulic conductivity values determinedusing this test method under the
6、prescribed set of conditions isnot considered to be representative of the in-service conditionsof GCLs. However, the test method allows the requester toestablish a set of test conditions; thus, the test method also maybe used to check performance or conformance, or both.1.5 The values stated in SI u
7、nits are to be regarded as thestandard, unless other units are specifically given. By traditionin U.S. practice, hydraulic conductivity is reported in centime-ters per second, although the common SI units for hydraulicconductivity are meters per second.1.6 This standard does not purport to address a
8、ll 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. Referenced Documents2.1 ASTM Standards:2D653 Terminology Re
9、lating to Soil, Rock, and ContainedFluidsD2216 Test Methods for Laboratory Determination of Water(Moisture) Content of Soil and Rock by MassD4439 Terminology for GeosyntheticsD4753 Guide for Evaluating, Selecting, and Specifying Bal-ances and Standard Masses for Use in Soil, Rock, andConstruction Ma
10、terials TestingD5887 Test Method for Measurement of Index FluxThroughSaturated Geosynthetic Clay Liner Specimens Using aFlexible Wall PermeameterE145 Specification for Gravity-Convection and Forced-Ventilation Ovens3. Terminology3.1 Definitions:3.1.1 flux, nthe rate of discharge of liquid under lami
11、narflow conditions through a unit cross-sectional area of a GCLspecimen at a standard temperature condition (22 6 3C).3.1.2 geosynthetic clay liner (GCL), n a factory-manufactured geosynthetic hydraulic barrier consisting of claysupported by geotextiles, geomembranes, or a combinationthereof, that a
12、re held together by needling, stitching, chemicaladhesives or other methods.3.1.3 hydraulic conductivity, k, nthe rate of discharge ofliquid under laminar flow conditions through a unit cross-sectional area of a GCL specimen under a unit hydraulicgradient and standard temperature conditions (22 6 3C
13、).3.1.3.1 DiscussionThe term coeffcient of permeability isoften used instead of hydraulic conductivity but hydraulicconductivity is used exclusively in this test method. A more1This test method is under the jurisdiction of ASTM Committee D35 onGeosynthetics and is the direct responsibility of Subcom
14、mittee D35.04 on Geosyn-thetic Clay Liners.Current edition approved July 1, 2012. Published September 2012. Originallyapproved in 2002. Last previous edition approved in 2009 as D676609. DOI:10.1520/D6766-12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Custome
15、r Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1complete discussion of the terminology
16、associated with Dar-cys law is given in the literature.33.1.4 index test, na test procedure that may contain bias,but may be used to establish comparable results with respect tothe property of interest.3.1.5 pore volume of flow, nthe cumulative quantity offlow into a test specimen divided by the vol
17、ume of voids in thespecimen.3.2 For definitions of other terms used in this test method,see Terminology D653 and D4439.4. Significance and Use4.1 This test method applies to one-dimensional, laminarflow of water or other aqueous solutions, such as chemicalsolutions, landfill leachate, and contaminat
18、ed water (here onreferred to as test liquid), through saturated/hydrated GCLspecimen that is consolidated and permeated under a pre-scribed or requested set of conditions.4.2 This test method can be performed to determine if theflux and/or hydraulic conductivity of a GCL specimen exceedsthe maximum
19、value stated by the manufacturer or required bythe regulatory agencies, or both.4.3 It is assumed that Darcys law is valid and that thehydraulic conductivity is essentially unaffected by hydraulicgradient. The validity of Darcys law may be evaluated bymeasuring the hydraulic conductivity of the spec
20、imen at threedifferent hydraulic gradients; if all measured values are similar(within about 25 %), then Darcys law may be taken as valid.However, when the hydraulic gradient acting on a test speci-men is changed, the state of stress will also change, and, if thespecimen is compressible, the volume o
21、f the specimen willchange. Thus, some change in hydraulic conductivity mayoccur when the hydraulic gradient is altered, even in caseswhere Darcys law is valid.4.4 This test method provides tools for determining flux andhydraulic conductivity values for a given GCL under thefollowing two different sc
22、enarios, which should be specified bythe requester:4.4.1 Scenario 1Hydrated/Saturated with Water Prior toContact with Test LiquidThis scenario simulates the fieldconditions where the GCL is well hydrated with water prior tocontact with actual test liquid. It should be noted that initialdegree of sat
23、uration/hydration greatly affects the hydraulicproperties of a GCL product. The test has two phases: (Phase1) hydrate, saturate, consolidate and permeate with water asTest Liquid 1, and (Phase 2) switch to permeation with testliquid as Test Liquid 2.4.4.2 Scenario 2Hydrated/Saturated with Test Liqui
24、d(Worst Case)This scenario simulates the field conditionswhere the GCLis in contact with test liquid prior to being fullyhydrated with water. It should be noted that this scenario mayresult in higher flux and hydraulic conductivity values com-pared to Scenario 1 as chemicals present in test liquid m
25、ay alterthe hydration and hydraulic properties of a GCL product.4.5 The apparatus used in this test method is commonlyused to determine the hydraulic conductivity of soil specimens.However, flux values measured in this test are typically muchlower than those commonly measured for most natural soils.
26、 Itis essential that the leakage rate of the apparatus in this test beless than 10 % of the flux.5. Apparatus5.1 CompatibilityAll parts in contact with the test liq-uid(s) shall be checked/verified for long-term compatibility.This can be established either based on the available informa-tion or by i
27、n-house testing.5.2 Hydraulic SystemConstant head (Method A), fallinghead (Methods B and C), or constant rate of flow (Method D)systems may be utilized provided they meet the criteriaoutlined as follows:5.2.1 Constant Head (Method A)The system must becapable of maintaining constant hydraulic pressur
28、es to within65 % and shall include means to measure the hydraulicpressures to within the prescribed tolerance. In addition, thehead loss across the tests specimen must be held constant towithin 65 % and shall be measured with the same accuracy orbetter. Pressures shall be measured by a pressure gage
29、, elec-tronic pressure transducer, or any other device of suitableaccuracy.5.2.2 Falling Head (Methods B and C) The system shallallow for measurement of the applied head loss, thus hydraulicgradient, to within 65 %. In addition, the ratio of initial headloss divided by final head loss over an interv
30、al of time shall bemeasured such that this computed ratio is accurate to within65 %. The head loss shall be measured with a pressure gage,electronic pressure transducer, engineers scale, graduatedpipette, or any other device of suitable accuracy. Falling headtests may be performed with either a fall
31、ing headwater andconstant tailwater elevation (Method B) or a falling headwaterand rising tailwater elevation (Method C).5.2.3 Constant Rate of Flow (Method D) The system mustbe capable of maintaining a constant rate of flow through thespecimen to within +5 %. Flow measurement shall be bycalibrated
32、syringe, graduated pipette, or other device of suit-able accuracy. The head loss across the specimen shall bemeasured to an accuracy of 5 % or better using an electronicpressure transducer or other device of suitable accuracy. Moreinformation on testing with a constant rate of flow is given inthe li
33、terature.45.2.4 System De-airingThe hydraulic system shall bedesigned to facilitate rapid and complete removal of free airbubbles from flow lines.5.2.5 Back Pressure SystemThe hydraulic system shallhave the capability to apply back-pressure to the specimen tofacilitate saturation. The system shall b
34、e capable of maintain-ing the applied back-pressure throughout the duration of3Olson, R. E. and Daniel, D. E. “Measurement of the Hydraulic Conductivity ofFine-Grained Soils,” Symposium on Permeability and Groundwater ContaminantTransport, ASTM STP 746, ASTM, 1981, pp. 1864.4Olson, H. W., Morin, R.
35、H., and Nichols, R. W., “Flow Pump Applications inTriaxialTesting,” Symposium on Advanced Triaxial Testing of Soil and Rock, ASTMSTP 977, ASTM, 1988, pp. 6881.D6766 122hydraulic conductivity measurements. The back-pressure sys-tem shall be capable of applying, controlling, and measuringthe back-pres
36、sure to 5 % or better of the applied pressure. Theback-pressure may be provided by a compressed gas supply(see Note 1), a deadweight acting on a piston, or any othermethod capable of applying and controlling the back-pressureto the tolerance prescribed in this paragraph.NOTE 1Application of gas pres
37、sure directly to a fluid will dissolve gasin the fluid.Any suitable technique, including separation of gas and liquidphases with a bladder, may be used to minimize dissolution of gas in theback-pressure fluid.5.3 Flow Measurement SystemBoth inflow and outflowvolumes shall be measured unless the lack
38、 of leakage, conti-nuity of flow, and cessation of consolidation or swelling can beverified by other means. Flow volumes shall be measured by agraduated accumulator, graduated pipette, vertical standpipe inconjunction with an electronic pressure transducer, or othervolume-measuring device of suitabl
39、e accuracy.5.3.1 Flow AccuracyRequired accuracy for the quantity offlow measured over an interval of time is 65%.5.3.2 De-airing and Compliance of the SystemThe flow-measurement system shall contain a minimum of dead spaceand be capable of complete and rapid de-airing. Compliance ofthe system in res
40、ponse to changes in pressure shall beminimized by using a stiff flow measurement system. Rigidtubing, such as metallic or rigid thermoplastic tubing, shall beused.5.3.3 Head LossesHead losses in the tubes, valves, porousend pieces, and filter paper may lead to error. To guard againstsuch errors, the
41、 permeameter shall be assembled with nospecimen inside and then the hydraulic system filled. If aconstant or falling head test is to be used, the hydraulicpressures or heads that will be used in testing a specimen shallbe applied, and the rate of flow measured with an accuracy of5 % or better.This r
42、ate of flow shall be at least ten times greaterthan the rate of flow that is measured when a GCL specimen isplaced inside the permeameter and the same hydraulic pres-sures or heads are applied. If a constant rate of flow test is tobe used, the rate of flow to be used in testing a specimen shallbe su
43、pplied to the permeameter and the head loss measured.The head loss without a specimen shall be less than 0.1 timesthe head loss when a GCL specimen is present.5.4 Permeant Interface Device (Bladder Accumulator) Apermeant interface device shall be used when a hazardous/corrosive or volatile test liqu
44、id, or both, is to be used as thepermeant. The permeant interface device shall contain the testliquid in a closed chamber and allow neither possible contami-nation of flow measurement and pressure systems nor potentialrelease of chemicals present in the test liquid to the breathingair, while maintai
45、ning the desired test pressures. A schematicdiagram of a typical permeant interface device is shown in Fig.1. The device consist of mainly a water chamber and a testliquid chamber, which are separated with a flexible bladdermembrane. The device should be checked for leaks at thedesired test pressure
46、s prior to the testing.5.5 Permeameter Cell-Pressure System The system forpressurizing the permeameter cell shall be capable of applyingFIG. 1 Schematic Diagram of Permeant Interface DeviceD6766 123and controlling the cell-pressure to within 65 % of the appliedpressure. However, the effective stress
47、 on the test specimen(which is the difference between the cell-pressure and the porewater pressure) shall be maintained to the desired value with anaccuracy of 65 % or better.The device for pressurizing the cellmay consist of a reservoir connected to the permeameter celland partially filled with de-
48、aired water, with the upper part ofthe reservoir connected to a compressed gas supply or othersource of pressure (see Note 2). The gas pressure shall becontrolled by a pressure regulator and measured by a pressuregage, electronic pressure transducer, or any other devicecapable of measuring to the pr
49、escribed tolerance. A hydraulicsystem pressurized by dead-weight acting on a piston or anyother pressure device capable of applying and controlling thepermeameter cell-pressure to the tolerance prescribed in thisparagraph may be used.NOTE 2De-aired water is commonly used for the cell fluid tominimize potential for diffusion of air through the membrane into thespecimen. Other fluids, such as oils, which have low gas solubility are alsoacceptable, provided they do not react with components of the permeame-ter. Also, use of a long (approximatel
