1、Designation: D4751 16Standard Test Methods forDetermining Apparent Opening Size of a Geotextile1This standard is issued under the fixed designation D4751; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A
2、 number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.This standard has been approved for use by agencies of the U.S. Department of Defense.1. Scope1.1 These test methods cover the determination of th
3、eapparent opening size (AOS) of a geotextile either by dry-sieving glass beads through a geotextile (Method A) or byusing a capillary porometer (Method B).1.2 Method B will not be used in lieu of Method A unlessthe prequalification procedure specified in this standard isfollowed.1.3 These test metho
4、ds show the values in both SI units andinch-pound units. SI units is the technically correct name forthe system of metric units known as the International System ofUnits. Inch-pound units is the technically correct name for thecustomary units used in the United States. The values ininch-pound units
5、are provided for information only.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-bility of regulatory limita
6、tions prior to use.2. Referenced Documents2.1 ASTM Standards:2C136/C136M Test Method for Sieve Analysis of Fine andCoarse AggregatesD1331 Test Methods for Surface and Interfacial Tension ofSolutions of Paints, Solvents, Solutions of Surface-ActiveAgents, and Related MaterialsD1776/D1776M Practice fo
7、r Conditioning and Testing Tex-tilesD4354 Practice for Sampling of Geosynthetics and RolledErosion Control Products(RECPs) for TestingD4439 Terminology for GeosyntheticsD6767 Test Method for Pore Size Characteristics of Geotex-tiles by Capillary Flow TestE11 Specification for Woven Wire Test Sieve C
8、loth and TestSievesE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3. Terminology3.1 Definitions: For general geosynthetics terms used in thisstandard, refer to Terminology D4439.3.2 Definitions:3.2.1 apparent opening size (AOS),O95, nfor a geotextile,
9、a property that indicates the approximate largest particle thatwould effectively pass through the geotextile.3.2.1.1 DiscussionWhile the same “O95” symbol is usedboth in these test methods for defining the AOS of a geotextileas well as in Test Method D6767 for determining the pore sizeof geotextiles
10、 by capillary flow, they are not necessarilyequivalent. The O95 values are defined in terms of theirrespective test methods. Therefore the AOS version of the O95value that is determined with Method B may not be identical tothe O95 value determined per Test Method D6767.4. Summary of Test Methods4.1
11、Glass Bead Dry-Sieving Method AA geotextile speci-men is placed in a sieve frame, and sized glass beads are placedon the geotextile surface. The geotextile and frame are shakenlaterally so that the jarring motion will induce the beads to passthrough the test specimen. The procedure is repeated on th
12、esame specimen with various size glass beads until its apparentopening size has been determined. This method is consideredthe referee method in the case of inter-laboratory disputesinvolving Method B.4.2 Capillary Porometer Method BA geotextile specimenis subject first to an air flow test, where the
13、 air flow rate andpressure are measured. Then the same specimen is wetted withmineral oil and subject to an increasing air pressure whilemeasuring the resulting flow rate. The opening sizes arecalculated from this data using standard capillary theory andthe specific algorithm defined in these test m
14、ethods.4.2.1 The apparent opening size of a geotextile is defined interms of the dry-sieving test method. This method includes a1These test methods are under the jurisdiction of ASTM Committee D35 onGeosynthetics and is the direct responsibility of Subcommittee D35.03 on Perme-ability and Filtration
15、.Current edition approved July 1, 2016. Published August 2016. Originallyapproved in 1993. Last previous version approved in 2012 as D4751-12. DOI:10.1520/D4751-16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Boo
16、k 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 States1procedure for correlating the porometer test data to the MethodA results so that Me
17、thod B is qualified to generate valuesequivalent to the glass bead dry-sieving Method A.5. Significance and Use5.1 Using a geotextile as a medium to retain soil particlesnecessitates compatibility between it and the adjacent soil. Thistest method is used to indicate the apparent opening size in ageo
18、textile, which reflects the approximate largest openingdimension available for soil to pass through.5.2 Test Methods D4751 for the determination of openingsize of geotextiles is acceptable for testing of commercialshipments of geotextiles. Current estimates of precision, be-tween laboratories, have
19、been established.5.3 Apparent Opening Test results obtained using MethodAmay differ from test results obtained with Method B. It is theintent of this test method to confirm the equivalency of theMethod B results before permitting the use of this alternative.Laboratories electing the use of Method B
20、must first determineany bias that exists between the two methods and document areliable correlation in accordance with this test method.5.3.1 The correlation between the Method B results and theMethod A results must be established and meet the require-ments of this test method for every different ge
21、otextile producttype tested with Method B. Geotextiles from different manu-facturers or with different nominal unit weights are considereddifferent products. A minimum of three test results must becompared with all three satisfying the established correlation.NOTE 1The correlation should be confirme
22、d for a particular productby comparing a minimum of three test results when there are changes inthe manufacturing of a specific pre-qualified geotextile.5.4 In case of a dispute arising from differences in reportedtest results when using Test Method D4751 for acceptancetesting of commercial shipment
23、s, the purchaser and the sup-plier should conduct comparative tests to determine if there isa statistical bias between their laboratories. Competent statis-tical assistance is recommended for the investigation of bias.As a minimum, the two parties should take a group of testspecimens that are homoge
24、neous as possible and that are froma lot of material of the type in question. The test specimensshould then be randomly assigned in equal numbers to eachlaboratory for testing. The average results from the twolaboratories should be compared using Students t-test forunpaired data and an acceptable pr
25、obability level chosen by thetwo parties before the testing is begun. If a bias is found, eitherits cause must be found and corrected or the purchaser and thesupplier must agree to interpret future test results in the light ofthe known bias.5.4.1 In the event that the dispute involves test resultspr
26、oduced with the capillary porometer, MethodAis consideredthe referee method for Test Methods D4751.6. Sampling6.1 Sampling of Planar Geotextiles:6.1.1 Lot SampleFor routine quality control testing, dividethe product into lots and take the lot sample as directed inPractice D4354, Section 7, Procedure
27、 BSampling for QualityAssurance Testing. For Specification Conformance testing,sample as directed in Practice D4354, Section 6, ProcedureASampling for Specification Conformance.6.1.2 Laboratory SampleAs a laboratory sample for ac-ceptance testing, take a full width swatch 1-m (1-yd) long fromthe end
28、 of each roll of fabric in the lot sample, after firstdiscarding a minimum of1m(1yd)offabric from the veryoutside of the roll.6.1.3 Test SpecimensCut five specimens from each swatchin the laboratory sample with each specimen being cut to fit theappropriate specimen holder for Method A or the poromet
29、ersample holder for Method B. Cut the specimens from a singleswatch spaced along a diagonal line on the swatch.6.2 Sampling of Circular-Knitted Sock Geotextiles:6.2.1 For a lot sample for manufacturers quality control(MQC) testing, divide rolls of Circular, Knitted Sock Geotex-tile Fabric into lots
30、and take the lot sample as directed inPractice D4354, Section 7, Procedure BSampling for QualityAssurance Testing. For a Lot Sample for Specification Confor-mance Testing, sample as directed in Practice D4354, Section8, Procedure CSampling for Specification Conformance.6.2.2 Laboratory SampleTo obta
31、in a laboratory samplefor MQC testing of the Circular-Knitted Sock Geotextile,follow the procedure below:6.2.2.1 Apply the knitted sock Geotextile sample over theoutside of the corresponding diameter of a 406 mm (16 in.)length of perforated tubing or reasonable facsimile having thesame diameter as t
32、he pipe material for which the sock isintended.6.2.2.2 Tie a knot in each end of the fabric so as to fullyencase the pipe in the fabric.6.2.2.3 Using the knot from one end of the fabric, suspendthe geotextiles encased pipe vertically. Gently suspend a1.13 kg (2.5 lb) weight from the bottom to ensure
33、 intimatecontact with the perforated pipe. See Fig. 1a. Allow thesuspended pipe with weight to hang for 2 min.NOTE 2Pipes with diameters larger than 75 to 150 mm (3 to 6 in.)may require heavier weights to ensure intimate contact between the pipeand sock material.6.2.2.4 For Method A, using a flexibl
34、e 203 mm (8 in.)diameter round template as a guide, trace a circle on the surfaceof the fabric using an indelible marker. See Fig. 1c. Removethe fabric from the pipe section by untying or cutting off theknots at one or both ends in the fabric. Cut the fabric tube in alengthwise direction at a positi
35、on opposing the drawn circle,taking care to not cut the fabric within the circle. If so desired,the length of the specimen may be shortened by cutting thefabric in a cross wise direction, taking care not to cut the fabriccloser than 75 mm (3 in.) from the outside of the circle. Theresult will be a p
36、lanar specimen of more or less rectangularshape with a circle drawn approximately in its center.6.2.2.5 For Method B test specimens, affix an adhesive-backed foil to the fabric which has a 25-mm diameter hole diecut from the center, and a sufficient outside diameter to exceedthe outside diameter of
37、the porometer sample holder. This foilmust be rigid enough to preserve the geometry of the materialproduced by this technique. The five foil-taped porometerspecimens are then cut with the porometer specimen die,positioning the 25-mm opening in the center.D4751 162FIG. 1D4751 1636.3 Lot Sample for Sp
38、ecification Conformance TestingSample as directed in Practice D4354, Section 8, ProcedureCSampling for Purchasers Specification Conformance Test-ing.6.3.1 Laboratory SampleTo obtain a laboratory sample ofthe Circular Knitted Geotextile Fabric for acceptance testing ofeach lot of pipe, follow this pr
39、ocedure:6.3.1.1 Selecta3m(10ft)section on each lot of the sockcovered pipe to be tested.6.3.2 Using a length of string, twine or cord, secure thefabric to the pipe at each end of the 3 m (10 ft) pipe section thatwas chosen in 6.3.1.1 in order to prevent the sock fabric fromcontracting lengthwise whe
40、n the sock covered pipe sample isremoved from the roll or pipe section. Remove the 3 m (10 ft)sock covered pipe section from the roll or pipe section bycutting the pipe at each end of the 3 m (10 ft) sample, outsideof the ties.6.3.3 Test SpecimensWith the fabric still secured to thepipe sample, usin
41、g a flexible 203 mm (8 in.) diameter roundtemplate for Method A, draw five 203-mm (8-in.) diametercircles at various locations around the circumference of eachlaboratory sample, equally spaced along its length, and notcloser than 100 mm (4 in.) from either end of the pipe sample.For Method B, affix
42、adhesive-backed foil to the fabric whichhas a 25-mm diameter hole die cut from the center, and asufficient outside diameter to exceed the outside diameter ofthe porometer sample holder. This foil must be rigid enough topreserve the geometry of the material produced by thistechnique. The five foil-ta
43、ped porometer specimens are thencut with the porometer specimen die, positioning the 25-mmopening in the center.6.3.3.1 Remove the ties from the laboratory sample andremove the fabric from the pipe.6.3.3.2 When securing specimens by wedging between twosieve frames cut the laboratory sample in a cros
44、s wise directionto create 5 specimens taking care not to make these cuts closertan 75 mm (3 in.) from the outside of the circle. Continue toprepare the specimens by cutting the fabric in a lengthwisedirection at a position opposing the circle. Care must be takennot to cut through the circle. The res
45、ult will be the creation of5 planar fabric specimens of more or less a rectangular shapewith a circle drawn at its center.METHOD ADRY-SIEVING WITH GLASS BEADS7. Specimen Preparation7.1 Weigh the Method A test specimens and then submergethem in distilled water for1hatthestandard atmosphere fortesting
46、. Bring the specimens to moisture equilibrium in theatmosphere for testing geosynthetics. Equilibrium is consid-ered to have been reached when the change in the mass of thespecimen in successive weight measurements made at intervalsof not less than 2 h does not exceed 0.1 g.7.2 The drying process ma
47、y be accelerated with the use of afan. The specimens shall not be dried in an oven or by exposingthem to elevated temperatures above the standard laboratoryatmosphere for geosynthetic testing.NOTE 3It is recognized that in practice, geosynthetic materials arefrequently not weighed to determine when
48、moisture equilibrium has beenreached. While such a method cannot be accepted in cases of dispute, itmay be sufficient in routine testing to expose the material to the standardatmosphere for testing geosynthetics for a reasonable period of timebefore the specimens are tested. A time of at least 24 h
49、has been foundacceptable in most cases. However, certain fibers may contain moremoisture upon receipt than after conditioning. When this is known, apreconditioning cycle, as described in Practice D1776/D1776M, may beagreed upon by the contractual parties.8. Apparatus8.1 Mechanical Sieve ShakerA mechanical sieve shaker,which imparts lateral and vertical motion to the sieve, causingthe particles thereon to bounce and turn so as to presentdifferent orientations to the sieving surface, should be used.The sieve shaker should be a constant frequency deviceutilizing
