1、Designation: D4884 12Standard Test Method forStrength of Sewn or Thermally Bonded Seams ofGeotextiles1This standard is issued under the fixed designation D4884; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revis
2、ion. 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 seam strength of geotextiles.The primary distinction of this test method for evaluating seamstrength
3、 is the width of the specimen. This is in contrast to themore narrow specimen width used in the tensile grab strengthtest discussed in Test Method D1683.1.2 This test method will provide data to indicate the seamstrength that can be achieved for each particular geotextile andseam assembly constructi
4、on.1.3 The values stated in SI units are to be regarded asstandard. The inch-pound units given in parentheses areprovided 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 standar
5、d 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:2D76 Specification for Tensile Testing Machines for TextilesD123 Terminology Relating to TextilesD1683 Test Method for Failure in
6、Sewn Seams of WovenApparel FabricsD1776 Practice for Conditioning and Testing TextilesD1777 Test Method for Thickness of Textile MaterialsD4439 Terminology for GeosyntheticsD4595 Test Method for Tensile Properties of Geotextiles bythe Wide-Width Strip MethodE178 Practice for Dealing With Outlying Ob
7、servationsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method2.2 Federal Standard:Fed. Std. No. 751a Stitches, Seams, and Stitchings33. Terminology3.1 Definitions:3.1.1 cross-machine directionthe direction in the plane ofthe geotextile perpendicular to th
8、e direction of manufacture.3.1.2 geotextile, na permeable geosynthetic comprisedsolely of textiles.3.1.3 linear density, nmass per unit length; the quotientobtained by dividing the mass of a fiber or yarn by its length.3.1.4 machine directionthe direction in the plane of thegeotextile parallel to th
9、e direction of manufacture.3.1.5 seam allowance, nthe width of geotextile used inmaking a seam assembly, for sewn seams bounded by the edgeof the geotextile and the furthest stitch line, and for thermallybonded seams bounded by the edge of the geotextile and thefurthest seam edge.3.1.5.1 DiscussionI
10、n geotextiles, the distance from theselvage or turned edge of the geotextile to the edge of the seam.3.1.6 seam assembly, nthe unit obtained by joining geo-textile with a seam, including details such as geotextiledirection(s), seam allowance, seam width, seam type, speed,and if sewnsewing threads us
11、ed and number of stitches perunit length, needle type and size, and so forth.3.1.7 seam effciency, nthe ratio expressed as a percentageof seam strength to geotextile strength.3.1.8 seam design engineering, nthe procedures used toselect a specific thread, a specific stitch type, and a specificseam ty
12、pe to achieve the required seam strength of a sewnseam and the procedures used to select a specific seam width,specific seam bonding temperature, and a specific seam speedand pressure to achieve the required seam strength of athermally bonded seam.3.1.9 seam interaction, nthe result of combining spe
13、cifictextile, a specific stitch type, and a specific seam type for asewn seam and the result of combining specific textile, a1This test method is under the jurisdiction of ASTM Committee D35 onGeosynthetics and is the direct responsibility of Subcommittee D35.01 on Mechani-cal Properties.Current edi
14、tion approved July 1, 2012. Published April 2012. Originallyap-proved in 1989. Last previous edition approved in 2009 as D4884 09e01. DOI:10.1520/D4884-12.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTM
15、Standards volume information, refer to the standards Document Summary page onthe ASTM website.3Available from Standardization Documents Order Desk, Bldg. 4 Section D, 700Robbins Ave., Philadelphia, PA 19111-5094, Attn: NPODS.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Cons
16、hohocken, PA 19428-2959. United States1specific seam width, a specific seam speed, and appliedpressure for a thermally bonded seam.3.1.10 seam type, nin sewn geotextiles, an alphanumericdesignation relating to the essential characteristics of geotextilepositioning and rows of stitching in a specific
17、 sewn geotextileseam (see Fed. Std. No. 751a).3.1.10.1 DiscussionThe first two letters of the designationshow seam type; the third and subsequent letter specify aparticular mating alignment; the number designation indicatesthe number of rows of stitches.3.1.11 seam weld, nthe process by which a seam
18、 is formedthrough the thermal bonding of separate layers of geotextile.3.1.12 selvage, nthe woven edge portion of a geotextileparallel to the machine direction.3.1.12.1 DiscussionThe edge of a nonwoven geotextilecannot be easily distinguished to determine either the machineor cross-machine direction
19、.3.1.13 sewing thread, na flexible, small diameter yarn orstrand, usually treated with a surface coating, or lubricant, orboth, intended to be used to stitch one or more pieces ofmaterial or an object to a material.3.1.14 sewn seam, nin sewn geotextiles,aseriesofstitches joining two or more separate
20、 plies of a material ormaterials of planar structure such as a textile geotextile.3.1.15 sewn seam strength, n for geotextiles, the maxi-mum resistance, measured in kilonewtons per metre, of thejunction formed by stitching together two or more planarstructures.3.1.16 stitch, nthe repeated unit forme
21、d by the sewingthread in the production of seams in a sewn geotextile (see Fed.Std. No. 751a).3.1.17 tensile strength, nthe maximum resistance of ma-terial to deformation in a tensile test carried to rupture; that is,the breaking load, or force per unit cross-sectional area of theunstrained specimen
22、.3.1.18 thermally bonded seam, n in geotextiles, a seammade by the application of thermal energy.3.1.19 thermally bonded seam strength, nfor geotextiles,the maximum shear resistance, measured in kilonewtons permetre, of the junction formed by thermally bonding togethertwo or more planar structures.3
23、.1.20 For definitions of other terms relating to textiles,refer to Terminology D123. For definitions of other termsrelating to geotextiles, refer to Terminology D4439.4. Summary of Test Method4.1 Aseam, 200 mm (8 in.) wide is gripped across the entirewidth in the clamps of a tensile testing machine,
24、 operated at aprescribed rate of extension, applying a longitudinal (perpen-dicular) force to the specimen until the seam or geotextileruptures.5. Significance and Use5.1 As explained in Test Method D4595, narrow geotextilespecimens demonstrate the tendency to contract (neck down) inthe gage area wh
25、en under stress. The wider width specimenwill minimize this phenomenon in seams during strengthtesting. The results achieved in this test method can moreaccurately correlate to the seam strength values anticipated inthe field.5.2 This test method can be used to measure the seamstrength of geotextile
26、s, and may also be used for acceptancetesting of commercial shipments of geotextiles. When strengthis not necessarily a design consideration of seam interaction, analternate method for determining the seam strength, such asTest Method D1683, may be used depending on the specifica-tion requirements.
27、Because current information about labora-tory precision is incomplete, comparative tests, as described in5.2.1, may be advisable.5.2.1 In case of a dispute arising from differences inreported test results when using this test method for acceptancetesting of commercial shipments, the purchaser and th
28、e sup-plier should perform 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 from the same lot of geotextile, that
29、utilize a likemethod of seam assembly to achieve seam interaction. Thespecimens should then be randomly assigned in equal numberto each laboratory for testing. If a bias is found, either its causemust be determined and corrected, or the purchaser and thesupplier must agree to interpret future test r
30、esults in light of theknown bias.5.3 Although other methods of determining seam strengthare available, this test method, that measures wide specimens,will more accurately correlate to the anticipated performance inthe field.5.4 This test method can be used to help determine seamdesign engineering fo
31、r the geotextiles being evaluated.6. Apparatus6.1 Tensile Testing Machine, must be of the constant-rate-of-extension (CRE) type, conforming to Specification D76 andequipped with a recorder having an adequate pen response orinterfaced computer to record the load elongation curve. Themachine must be s
32、et to a rate of extension of 10 6 3 %/min.6.2 ClampsThe clamps shall be wide enough to grip theentire width of the specimen and have the appropriate clampingpower to hold the test specimen in place without crushing(damaging) the machine direction and cross-machine directionyarns.6.2.1 Caution must b
33、e taken to ensure that the type of clampused is adequate for the seam strength being measured.6.3 Size of Jaw FacesEach clamp shall have a bearingface measuring wider than the width of the specimen, 200 mm(8 in.) and a minimum of 50 mm (2 in.) in length, in thedirection of the applied force. The siz
34、e of jaw faces does notapply if roller clamps are used.7. Sampling for Acceptance Testing and Number ofSpecimens7.1 Division into Lots and Lot Sample Divide the materialinto lots and take a lot sample as described in an applicableD4884 122material specification, or as agreed upon between the purchas
35、erand the supplier. In the absence of an applicable materialspecification or prior agreement between the purchaser and thesupplier, sampling and testing intervals should be agreed uponbetween the purchaser and the supplier.7.1.1 When the installation project requires that seams aremade in both the m
36、achine and cross-machine directions, thenumber of samples and the subsequent specimens will increaseproportionately.7.2 Laboratory SamplesAt a laboratory sample, cut aminimum of two swatches of geotextile from each of the lotunits selected for testing. The swatches must be a minimum of2000 mm (79 in
37、.) in length and a minimum of 300 mm (12 in.)in width. The lengthwise direction of these swatches must becut from opposite ends and opposite sides of the lot samplerolls and should be parallel to the direction in which the seamwill be made.7.2.1 When seams are made in both the machine andcross-machi
38、ne direction, it is suggested that some type ofspecial color identification marking be used to distinguish onefrom the other.7.2.2 These swatches are then joined using the best seamengineering techniques determined by the purchaser and thesupplier to achieve seam interaction.7.2.3 It will be necessa
39、ry to cut a sufficient number ofswatches for both wet and conditioned tests.7.3 Test Specimens:7.3.1 Number of SpecimensIn the absence of an appli-cable specification or prior agreement between the purchaserand the supplier, prepare at least six test specimens from thelaboratory samples.7.3.2 Test S
40、pecimen SizePrepare test specimens from thelaboratory sample. Each specimen should be approximately250 mm (10 in.) wide with a stitch line in the center for sewnseams or approximately 200 mm (8 in.) wide with the seamweld in the center for thermally bonded seams running parallelto either the machine
41、 or cross-machine directions as shown inFig. 1(a) for sewn seams or Fig. 1(b) for thermally bondedseams.7.3.2.1 Cut this wider specimen for sewn seams as shown inFig. 1(a) to achieve a final test specimen width of 200 mm (8in.). When removing the shaded area from a specimen asshown in Fig. 1(a), the
42、 angles between the 25-mm extensionswhich are parallel to the seam and that section of the specimenhaving a finished width of 200 mm is 90.7.3.2.2 For some seaming patterns, cutting the thread maylead to a loss of the integrity of the seam, and thus to anunderestimation of the seam strength. For the
43、se patterns, somemeans shall be used to lock the thread in place, such as usingglue, or mechanically locking the thread on both ends of theseam by un-sewing the seam over a maximum length of 25mm,without damaging the sewing thread, in order to have at least200 mm of intact seam centered in the axis
44、of the specimen.Both upper and lower threads of the seam shall then be tiedtogether to avoid any further modification to the structure ofthe stitch during the test.8. Sampling of Field Seams and Factory Seams8.1 The evaluation of field seams and factory seams will bemade by taking samples at the sti
45、pulated intervals directed inTable 1 unless otherwise stated.NOTE 1To prevent the unnecessary waste of geotextile or impede theinstallation, it should be agreed upon between the supplier and thepurchaser that all seam samples can be taken from alternate sides of panelsat or near the end of the rolls
46、.8.2 The lengthwise direction of these swatches should beparallel to the direction of the seam, either in the machine orcross-machine direction.8.2.1 It will be necessary to cut additional swatches for bothwet and conditioned tests to be performed.FIG. 1 (a) Test Specimen Preparation for Sewn Seam (
47、Front View)FIG. 1 (b) Test Specimen Preparation for Thermally Bonded Seam(Front View) (continued)TABLE 1 Seam Quality Control Sampling RequirementsTotal Length of FieldASeams for Project, m (yd)Sample IntervalBRequirements, m (yd)Up to 10 000 (Up to 11 000) 1000 (1100)10 001 to 150 000 (11 000 to 16
48、5 000) 1500 (1666)150 000 and up (165 000 and up) 2000 (2200)ATotal length of field seams for project is the sum of all machine direction andcross-machine direction seams required to effect installation of geotextile(s).BSamples will be taken at stipulated intervals along the total length of the fie
49、ldseams. The number of such intervals will be rounded to the next higher wholenumber.D4884 1238.3 Prepare test specimens as specified in Section 7, 7.3.2,and, if sewn, 7.3.2.1.9. Conditioning9.1 Bring the specimens to moisture equilibrium in theatmosphere for testing geotextiles. Equilibrium is considered tohave been reached when the increase in mass of the specimenin successive weighings made at intervals of not less than 2 hdoes not exceed 0.1 % of the mass of the specimen. Unless thepurchaser and the supplier agree otherwise, bring the testspecim
