1、Designation: D6767 11D6767 14Standard Test Method forPore Size Characteristics of Geotextiles by Capillary FlowTest1This standard is issued under the fixed designation D6767; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year
2、 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 the determination of the pore size distribution of geotextile filters with pore sizes rang
3、ing from 1to 5001000 m.NOTE 1The accuracy of this procedure has been verified up to a maximum pore size of 200500 m. Above this value accuracy has been found tobe equipment dependent and should be verified by the user through checks on materials with known opening sizes.1.2 The test method measures
4、the entire pore size distribution in terms of a surface analysis of specified pore sizes in ageotextile, defined in terms of the limiting diameters.1.3 The analyst should be aware that adequate collaborative data for bias statements as required by Practice D2777 is notprovided. See the precision and
5、 bias section for details.1.3 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.4 This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address allof the safety concerns, i
6、f any, associated with its use. It is the responsibility of the user of this standard to establish appropriatesafety and health practices and determine the applicability of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD2777D1193 Pr
7、actice for Determination of Precision and Bias of Applicable Test Methods of Committee D19 on Specificationfor Reagent WaterD4354 Practice for Sampling of Geosynthetics and Rolled Erosion Control Products(RECPs) for TestingD4439 Terminology for Geosynthetics3. Terminology3.1 DefinitionsFor definitio
8、ns of other terms used in thesethis test methods,method, refer to DefinitionsTerminologies D4439and D1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 bubble point pore size (O98) , ), nthe largest effective pore diameter detected by the sudden increase of flow rate at thebeginning of th
9、e wet test.3.2.2 pore constriction (O), ndiameter of a circle having the same area as the smallest section of a given pore.3.2.3 pore size (Oi), ncapillary equivalent pore diameter for which the percent of total pore diameters i in a given geotextilebased on the surface occupied by the pores are sma
10、ller than or equal to that diameter.3.2.4 pore size distribution (PSD), npercent cumulative distribution of the complete range of pore sizes with in a givengeotextile based on the surface occupied by the pores.1 This test method is under the jurisdiction of ASTM Committee D35 on Geosynthetics and is
11、 the direct responsibility of Subcommittee D35.03 on Permeability andFiltration.Current edition approved Feb. 1, 2011July 1, 2014. Published March 2011July 2014. Originally approved in 2002. Last previous edition approved in 20082011 asD676708.11. DOI: 10.1520/D6767-11.10.1520/D6767-14.2 For referen
12、cedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document is not an ASTM standard and is intended only to provide the
13、user of an ASTM standard an indication of what changes have been made to the previous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard
14、 as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13.2.5 wetting liquid, nliquid used to submergewet the geotextile specimen prior to beginning the test.test specimen for th
15、ecapillary porometry portion of the test method, that is, the “wet” test. The verb “wet” is intended to mean to completely saturatethe geotextile specimen with the wetting fluid thoroughly such that the entire thickness of the specimen contains fluid with noentrained air bubbles.4. Summary of Test M
16、ethod4.1 Geotextile filters have discrete pores from one side to the other of the geotextile. The bubble point test is based on theprinciple that a wetting liquid is held in these continuous pores by capillary attraction and surface tension, and the minimumpressure required to force liquid from thes
17、e pores is a function of pore diameter.4.2 A fluid-wet geotextile will pass air when the applied air pressure exceeds the capillary attraction of the fluid in the poreconstriction. Smaller pore constrictions will exhibit similar behavior at higher pressures. The relationship between pore size andpre
18、ssure has been established for water.the wetting fluid.4.3 By comparing the gas flow rates of both a wet and dry geotextiletest at the same pressures, the percentage of the flow passingthrough the filter pores larger than or equal to the specified size may be calculated from the pressure-size relati
19、onship. Byincreasing pressure in small steps, it is possible to determine the flow contribution of very small pore size increments by difference.5. Significance and Use5.1 This test method may be used to:5.1.1 Determine the pore size distribution of a geotextile,5.1.2 Determine the maximum pore size
20、 of a geotextile,5.1.3 Determine the mean flow pore size of a geotextile,5.1.4 Determine the effect of processes such as calenderingcalendaring or needle punching upon the pore size distribution,5.1.5 Determine the effect of compression upon the pore size distribution of a geotextile, andif the test
21、 equipment allows,5.1.6 Determine the gas flow rate of a geotextile, and thereby its gas flow capability.5.2 The pore size distribution test is significant not only for indicating pore sizes, but may also indicate a damaged,contaminated, or clogged geotextile.may also be used for research, material
22、development or to assess clogging on field-retrievedsamples.6. Apparatus6.1 Clean Gas Pressure Source, with regulation (filtered air or nitrogen).air).6.2 Pressure Transducer, U-tube Manometer or Gage, Sensor, (or set of gages), pressure measurements may be obtained witha digital pressure transducer
23、 a U-Tube manometer or an inclined manometer covering the necessary pressure range for the poresizes under study (seeand Table 1).the wetting fluid used. The pressure sensor sensitivity shall be dictated by the range of pressuresassociated with the openings sizes. The bubble point pressure should b
24、e measured with an accuracy of 61 % or 65 Pa, whicheveris larger.6.2.1 Pressure sensor(s) must be installed immediately upstream (for example, within 5 mm) of the sample holder.NOTE 2Pressure measurements must be installed immediately upstream (for example, within 5 mm) of the sample holder.6.3 Clos
25、ed Filter Holder, (see Fig. 1 and Fig. 2).6.3.1 Filter holder for the test specimens that fully confines the perimeter of the specimen to prevent any lateral pressure losses.6.3.2 The specimen flow area shall be 25-mm diameter. Other diameters shall be verified with comparative tests with thestandar
26、d 25-mm diameter.FIG. 1 Closed Filter HolderD6767 1426.3.3 The filter holder should be checked for leaks by placing an impermeable membrane in the holder and increasing thepressure to the maximum capacity of the pressure sensor and holding it for a period of 1 min. The flow rate measured during this
27、period must be “zero.”NOTE 3The filter holder should be checked for leaks by placing a geomembrane in the holder and increasing the pressure to 70 kN/m2 and holdingit for a period of one minute.6.4 Metal Punch, used to cut a suitable size geotextile from the test sheet to fit the test filter holder.
28、6.5 Set of Flowmeters, Flow Rate Measurement Sensors, covering the range from 0 to 5000 the porometer should be equippedwith sensors to measure the flow rate that are high enough to derive the desired pore size distribution. The maximum flow ratemeasurement required will depend on the opening diamet
29、er and the dry air flow that corresponds to the smallest opening that canbe determined with this method on the geotextile type under test. The minimum sensitivity, that is, the detection threshold, isdictated by the flow rate that corresponds to the onset of flow at the bubble point. For some geotex
30、tiles, this value may be as lowas 0.1 L/min.6.5.1 A series of floating ball-type flow meters placed in a parallel arrangement to cover the ranges of flow rates is acceptableprovided the minimum and maximum flow rate measurements can be obtained with an accuracy of 5 % or less of the measuredvalue.6.
31、5.2 Digital flow meters are preferred for measurement of flow rates. Two or more digital flow meters of different capacitiesand sensitivities may be necessary to cover both the minimum detection value and the maximum dry specimen value. The accuracyof digital flow meters shall be 0.25 % of the maxim
32、um reading.NOTE 4Four flowmeters with flow rates of 0 to 0.4, 0 to 2.5, 0 to 25, and 0 to 100 L/min, placed in a parallel arrangement to cover the range of flowrates anticipated are recommended for geotextiles. The smallest flow rate that could be measured by the flowmeters is typically reported to
33、be 0.02 L/min.The manufacturer-rated precision of each flowmeter is typically reported to be 0.25 percent of the maximum reading.6.6 In-Line Fluid Trap, for porometers which have the flow rate sensors downstream from the test specimen to protect theflowmeters from the flow meters from being contamin
34、ated by the exhausted fluid.6.7 Appropriate Fittings, Hose, Connectors, Piping, to assemble apparatus as shown in apparatus.Figs. 3 and 4.6.8 x-y Recorder, Balance, to assist in graphing results of mean flow pore test.with a precision of 0.001 g.7. Sampling7.1 Lot SampleFor routine Quality Control t
35、esting, divide the product into lots and take the lot sample as directed in PracticeD4354, Section 7 “Procedure B Sampling for Quality Assurance Testing.” For Specification Conformance testing, sample asdirected in Practice D4354, Section 6 “Procedure A-Sampling for Specification Conformance.”7.2 La
36、boratory SampleAs a laboratory sample for acceptance testing, take a full width swatch 1 m long from the end of eachroll of fabric in the lot sample, after first discarding a minimum of 1 m of fabric from the very outside of the roll.7.3 Test SpecimensCut five specimens from each swatch in the labor
37、atory sample with each specimen being cut to fit theappropriate sieve pan. Cut the specimens from a single swatch regularly spaced along a diagonal line on the swatch.8. Specimen Preparation8.1 Weigh the specimens previously conditioned at the standard atmosphere for testing geosynthetics to 0.001 g
38、8.2 Submerge them in water for 1 h.8.3 Weigh the specimens, submerge them in water for 1 h, and then allow the Allow the specimens to air dry at the standardatmosphere for testing. testing geosynthetics. The specimen must be completely dry before testing. Weigh the specimen to 0.001g after air dryi
39、ng until a constant weight equal to or less than the initial weight of the specimen is achieved. Air may be blownover the specimens with a fan to facilitate drying.Alternatively, condition the specimens 24 h at the standard atmosphere for testinggeosynthetics.9. Wetting Liquids9.1 Purity of Reagents
40、Reagent grade chemicals shall be used for wetting liquids in all tests. Unless otherwise indicated, it isintended that all reagents shall conform to the specifications of the Committee on Analytical Reagents of the American ChemicalSociety where such specifications are available.3 Other grades may b
41、e used provided it is first ascertained that the reagent is ofsufficient high purity to permit its use without lessening the accuracy of the determination.9.2 Water, conforming to Specification D1193, Type IV or higher purity.9.3 Denatured Alcohol.3 Reagent Chemicals, American Chemical Society Speci
42、fications, Am. Chemical Soc., Washington, DC. For suggestions on the testing of reagents not listed by theAmerican Chemical Society, see “Reagent Chemicals and Standards,” by Joseph Rosin, D. Van Nostrand Co., Inc., New York, NY, and the “United States Pharmacopeia.”D6767 1439.3 Mineral Oil,Wetting
43、Fluid, such as the standard wetting fluid for this test method is Mineral Oil, USP liquid petrolatumheavy, with surface tension of 34.7 dynes/cm at 25C.9.3.1 Other wetting fluids may be used as a deviation from the standard. The user shall then verify the consistency of theresulting opening size dis
44、tribution with the distribution obtained with Mineral Oil using comparative tests.9.5 PorewickTM, 59.6 SilwickTM, 59.7 GalwickTM, 59.4 Clean Gas Pressure Source, with regulation (filtered air or nitrogen).air).NOTE 5Table 1 lists the nominal surface tension of these liquids at 25C. There is a potent
45、ial influence of the liquid on a measurement of pore size,which should be taken into account by users through verification tests on materials with known pore size. Other liquids can be used and several arecurrently under evaluation10. Procedure for One Holder (see Fig. 3)10.1 Place a dry geotextile
46、sample disk in the geotextile holder.10.2 Close the holder and apply gas pressure in increments.pressure.10.2.1 The pressure shall first be increased from zero to a pressure lower to, but close to the pressure associated with the smallestopening. No flow should be detected through the specimen at th
47、is stage.10.2.2 The pressure shall then be increased at a constant rate. The rate at which the pressure is increased can affect the resultingopening distribution. The pressure ramp rate should be slow enough not to produce a “right-shift” of the wet curve, that is,underestimate of the opening size.
48、This should be confirmed with consecutive tests using a single test specimen tested at varyingpressure ramp rates. Pressure and flow rate shall be recorded with an acquisition rate sufficient to capture the requisite values.10.3 Plot gas the air flow rate versus gas pressure over the intended range
49、of use.10.4 Reduce gas pressure and remove the geotextile from the holder.10.5 Completely wet the geotextile by submerging it in wetting liquids (for example, water) the wetting liquid for a period of30 min. Replace the wet geotextile in the holder, and apply a slight pressure, checking to see that a tight seal exists. This pressuremust not exceed the bubble point pore size.1 h. Air bubbles should not be entrained in the wetting fluid.10.6 Increase the pressure using the same precautions regarding the ramp rate and data acquisition rate described in 10.2.2.10.
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