1、Designation: D 6767 02Standard Test Method forPore Size Characteristics of Geotextiles by Capillary FlowTest1This standard is issued under the fixed designation D 6767; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of la
2、st 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 test method covers the determination of the poresize distribution of geotextile filters with pore sizes rangingfro
3、m 1 to 500 m.NOTE 1The accuracy of this procedure has been verified up to amaximum pore size of 200 m. Above this value accuracy has been foundto be equipment dependent and should be verified by the user throughchecks on materials with known opening sizes.1.2 The test method measures the entire pore
4、 size distribu-tion 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 collaborativedata for bias statements as required by Practice D 2777 is notprovided. See the precision and bias section
5、for details.1.4 This standard may involve hazardous materials, opera-tions, and equipment. This standard does not purport toaddress all of the safety concerns, if any, associated with itsuse. It is the responsibility of the user of this standard toestablish appropriate safety and health practices an
6、d deter-mine the applicability of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:D 1129 Definition of Terms Relating to Water2D 2777 Practice for Determination of Precision and Bias ofApplicable Methods of Committee D-19 on Water2D 4354 Practice for Sampling Geosynthet
7、ics (for Testing)3D 4439 Terminology Relating to Geosynthetics3E 128 Test Method for Maximum Pore Diameter and Per-meability of Rigid Porous Filters for Laboratory Use4F 316 Pore Size Characteristics of Membrane Filter byBubble Point and Mean Flow Pore Test43. Terminology3.1 DefinitionsFor definitio
8、ns of other terms used in thesetest methods, refer to Definitions D 4439 and D 1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 bubble point pore size (O98), nthe largest effectivepore diameter detected by the sudden increase of flow rate atthe beginning of the wet test.3.2.2 pore const
9、riction (O), ndiameter of a circle havingthe same area as the smallest section of a given pore.3.2.3 pore size (Oi), ncapillary equivalent pore diameterfor which the percent of total pore diameters i in a givengeotextile based on the surface occupied by the pores aresmaller than or equal to that dia
10、meter.3.2.4 pore size distribution (PSD), npercent cumulativedistribution of the complete range of pore sizes with in a givengeotextile based on the surface occupied by the pores.3.2.5 wetting liquid, nliquid used to submerge the geo-textile specimen prior to beginning the test.4. Summary of Test Me
11、thod4.1 Geotextile filters have discrete pores from one side tothe other of the geotextile. The bubble point test is based on theprinciple that a wetting liquid is held in these continuous poresby capillary attraction and surface tension, and the minimumpressure required to force liquid from these p
12、ores is a functionof pore diameter.4.2 A fluid-wet geotextile will pass air when the applied airpressure exceeds the capillary attraction of the fluid in the poreconstriction. Smaller pore constrictions will exhibit similarbehavior at higher pressures. The relationship between poresize and pressure
13、has been established for water.4.3 By comparing the gas flow rates of both a wet and drygeotextile at the same pressures, the percentage of the flowpassing through the filter pores larger than or equal to thespecified size may be calculated from the pressure-size rela-tionship. By increasing pressur
14、e in small steps, it is possible todetermine the flow contribution of very small pore sizeincrements 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 of a geotextile,5.1.3 Determi
15、ne the mean flow pore size of a geotextile,5.1.4 Determine the effect of processes such as calenderingor needle punching upon the pore size distribution,1This test method is under the jurisdiction of ASTM Committee D35 onGeosynthetics and is the direct responsibility of Subcommittee D35.03 on Hydrau
16、licProperties.Current edition approved Feb 10, 2002. Published August 2002.2Annual Book of ASTM Standards, Vol 11.01.3Annual Book of ASTM Standards, Vol 04.02.4Annual Book of ASTM Standards, Vol 14.02.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959
17、, United States.5.1.5 Determine the effect of compression upon the poresize distribution of a geotextile, and5.1.6 Determine the gas flow rate of a geotextile, andthereby its gas flow capability.5.2 The pore size distribution test is significant not only forindicating pore sizes, but may also indica
18、te a damaged,contaminated, or clogged geotextile.6. Apparatus56.1 Clean Gas Pressure Source, with regulation (filtered airor nitrogen).6.2 Pressure Transducer, U-tube Manometer or Gage, (orset of gages), covering the necessary pressure range for thepore sizes under study (see Table 1).NOTE 2Pressure
19、 measurements must be installed immediately up-stream (for example, within 5 mm) of the sample holder.6.3 Closed Filter Holder, (see Fig. 1).NOTE 3The filter holder should be checked for leaks by placing ageomembrane in the holder and increasing the pressure to 70 kN/m2andholding it for a period of
20、one minute.6.4 Metal Punch, used to cut a suitable size geotextile fromthe test sheet to fit the test filter holder.6.5 Set of Flowmeters, covering the range from 0 to 100L/min.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 t
21、o cover the range offlow rates anticipated are recommended for geotextiles. The smallest flowrate that could be measured by the flowmeters is typically reported to be0.02 L/min. The manufacturer-rated precision of each flowmeter istypically reported to be 0.25 percent of the maximum reading.6.6 In-L
22、ine Fluid Trap, to protect the flowmeters from thefluid.6.7 Appropriate Fittings, Hose, Connectors, Piping,toas-semble apparatus as shown in Figs. 2 and 3.6.8 x-y Recorder, to assist in graphing results of mean flowpore test.7. Sampling7.1 Lot SampleFor routine Quality Control testing, dividethe pro
23、duct into lots and take the lot sample as directed inPractice D 4354, Section 7 “Procedure B Sampling for QualityAssurance Testing.” For Specification Conformance testing,sample as directed in Practice D 4354, Section 6 “ProcedureA-Sampling for Specification Conformance.”7.2 Laboratory SampleAs a la
24、boratory sample for accep-tance testing, take a full width swatch 1 m long from the endof each roll of fabric in the lot sample, after first discarding aminimum of1moffabric from the very outside of the roll.7.3 Test SpecimensCut five specimens from each swatchin the laboratory sample with each spec
25、imen being cut to fit theappropriate sieve pan. Cut the specimens from a single swatchspaced along a diagonal line on the swatch.8. Specimen Preparation8.1 Weigh the specimens and then submerge them in dis-tilled water for 1 h and allow to air dry at the standardatmosphere for testing.9. Wetting Liq
26、uids9.1 Purity of ReagentsReagent grade chemicals shall beused for wetting liquids in all tests. Unless otherwise indicated,it is intended that all reagents shall conform to the specifica-tions of the Committee on Analytical Reagents of the AmericanChemical Society where such specifications are avai
27、lable.6Other grades may be used provided it is first ascertained thatthe reagent is of sufficient high purity to permit its use withoutlessening the accuracy of the determination.9.2 Water, conforming to Specification D 1193, Type IV orhigher purity.9.3 Denatured Alcohol.9.4 Petroleum Distillate, wi
28、th surface tension of 30dynes/cm at 25C.9.5 Mineral Oil, such as USP liquid petrolatum heavy, withsurface tension of 34.7 dynes/cm at 25C.9.6 1,1,2-trichloro-1,2,2-trifluoret hane. (Freon TFt), avail-able from commercial chemical supply houses.9.7 Clean Gas Pressure Source, with regulation (filtered
29、 airor nitrogen).NOTE 5Table 1 lists the nominal surface tension of these liquids at25C. There is a potential influence of the liquid on a measurement of poresize, which should be taken into account by users through verification testson materials with known pore size. Other liquids can be used and s
30、everalare currently under evaluation10. Procedure for One Holder (see Fig. 2)10.1 Place a dry geotextile sample disk in the geotextileholder.10.2 Close the holder and apply gas pressure in increments.10.3 Plot gas flow versus gas pressure over the intendedrange of use.10.4 Reduce gas pressure and re
31、move the geotextile fromthe holder.10.5 Completely wet the geotextile by submerging it inwetting liquids (for example, water) for a period of 30 min.Replace the wet geotextile in the holder, and apply a slight5Different equipment is available for obtaining pore size measurements includ-ing commercia
32、lly available equipment from Porous Materials Inc. (PMI) (withspecial modifications for geotextiles) and Beckman Coulter, Inc. The equipmentdevelopers should be contacted for limitation specifically in relation to measuringthe larger opening sizes of geotextiles.6Reagent Chemicals, American Chemical
33、 Society Specifications, Am. ChemicalSoc., Washington, DC. For suggestions on the testing of reagents not listed by theAmerican Chemical Society, see “Reagent Chemicals and Standards,” by JosephRosin, D. Van Nostrand Co., Inc., New York, NY, and the “United StatesPharmacopeia.”TABLE 1 Pressure Range
34、s RequiredFluidUsedPore Size Range to be InvestigatedSurfaceTensiondynes/cmat 25C$ 100 m $ 50 m $ 10 m $ 1mWater 0 to 2.5 kPa 0 to 7.5 kPa 0 to 25 kPa 0 to 200 kPa 72Petroleumdistillate0 to 100 kPa 30Mineraloil0 to 75 kPa 34.7D6767022pressure, checking to see that a tight seal exists. This pressurem
35、ust not exceed the bubble point pore size.10.6 Plot the fluid-wet filter gas flow versus pressure on thesame coordinates as for the plot made in accordance with 10.3.10.7 Reduce the pressure, remove the filter, and clean theholder for the next test.11. Procedure for Two Holders (see Fig. 3)11.1 Plac
36、e a dry geotextile in the holder to be used exclu-sively for dry geotextiles.11.2 Wet a geotextile of the same type and lot as thegeotextile used in 11.1, in reagent and place it in a holder to beused exclusively for wet geotextiles.11.3 Apply gas pressure to the dry geotextile and plot gasflow vers
37、us gas pressure.11.4 Change the two position valve to apply gas pressure tothe wet geotextile holder and record the first gas flow asFIG. 1 Closed Filter HolderFIG. 2 Setup for One HolderFIG. 3 Setup for Two HoldersD6767023detected by the capillary tube as the bubble point. Switch toflowmeters and p
38、lot fluid-wet gas flow versus gas pressure.12. Calculation of Pore Size, Pore Size Distribution andFrequency12.1 The calculation of pore size is based on the equilibriumof forces as shown by Eq 1.p Oig B cosu5Sp4DO2P (1)where:Oi= pore size, m,g = surface tension, mN/m, (dynes/cm),P = pressure, Pa or
39、 cm Hg, andB = capillary constant.The left-hand side of Eq 1 is the resisting force developedfrom surface tension acting between the liquid and the side-walls of a pore constriction of diameter O. The right-hand sideof Eq 1 is the driving force developed from the appliedpressure multiplied by the ar
40、ea of the pore constriction. Eq 2 isderived by rewriting Eq 1 to solve for O.O 54TB cosu!P(2)If the test liquid is known to wet the geotextile completely,and u = 0, then:O 5C gP(3)where:C = constant, 2860 when P is in Pa, 2.15 when P is in cmHg, and 0.415 when P is in psi units.NOTE 6If the contact
41、angle is greater than zero, the calculatedeffective pore size will be larger than the actual effective pore size rating.12.2 Select the limits of the pore size range being evaluated.Substitute the limits individually into the pore-size versuspressure formula, obtain their respective pressures and pl
42、ot theresults. From the test results, determine the wet and dry flowsat each pressure measured in the wet test and extrapolated fromthe dry curve over the pressure limits (pore size limits of therange) as shown in Fig. 4.12.3 The PSD of a geotextile is found by using Eq 4 at eachdifferent pressure a
43、nd flow rate measured.% Finer 5F1 2wet flow rate!dry flow rate!G100! (4)NOTE 7Since the change in pore size per unit change in appliedpressure is greatest at large pore sizes and diminishes hyperbolically,repeatability and reproducibility increase accordingly with applied pres-sure.13. Report13.1 Re
44、port the geotextile identification, date and time oftest, and all pertinent general testing conditions.13.2 Indicate in a table for each tested specimen: BubblePoint (O98) and values (O95, O90, O85, O60, O30, O15, O10, O5).Indicate the mean values and the coefficient of variation foreach pore size.1
45、3.3 Provide a complete pore size distribution curve show-ing the pore size on the x-axis and percent finer than on they-axis as shown in the example in Fig. 5.14. Precision and Bias14.1 Results should not differ from the mean by more thanthe following amounts:Pore SizeRangeRepeatability, %Same Opera
46、torand ApparatusReproducibility, %Different Operatorand ApparatusGreater than 100 m 2 410 to 100 m 1 2.51to10m 0.5 1FIG. 4 Example of Pore Size Frequency DeterminationD6767024APPENDIXX1. PORE SIZE FORMULA DERIVATIONX1.1 The pore size formula is derived as follows:Surface tension formula:g5hpgr2 cos
47、fbRearranging for diameter (2r):d 54 cos fBghpgAt bubble point pressure P = hgp:d 54 cos fBgPWhen a fluid wets a filter cos f =1:d 54 BgPwhere:h = height of rise,p = density of fluid,g = gravitational constant,r = radius of tube,f = contact angle,B = capillary constant,7andg = surface tension.Substi
48、tuting pressure conversion factors and the capillaryconstant:For centimetres of HG:d 52.145 g dynes/cm!#P cm Hg!#For psi:d 50.415 g dynes/cm!#P psi!#For Pa:d 52860 g dynes/cm!#P Pa!#7Bechold, H., “The Permeability of Ultrafilters,” Zeitschrift fuer Physik andChemie, Vol 64, 1908, p. 328.FIG. 5 Typic
49、al Geotextile Pore Size Distribution CurveD6767025ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must be reviewed every five years andif not revised, either reapprov
