ASTM_D_4885_-_01_2011.pdf

Designation:D488501(Reapproved 2011)Standard Test Method forDetermining Performance Strength of Geomembranes bythe Wide Strip Tensile Method1This standard is issued under the fixed designation D4885;the number immediately following the designation indicates the year oforiginal 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 the determination of the perfor-mance strength of synthetic geomembranes by subjecting widestrips of material to tensile loading.1.2 This test method covers the measurement of tensilestrength and elongation of geomembranes and includes direc-tions for calculating initial modulus,offset modulus,secantmodulus,and breaking toughness.1.3 The basic distinctions between this test method andother methods measuring tensile strength of geomembranes arethe width of the specimens tested and the speed of appliedforce.The greater width of the specimens specified in this testmethod minimizes the contraction edge effect(necking)whichoccurs in many geosynthetics and provides a closer relation-ship to actual material behavior in service.The slower speed ofapplied strain also provides a closer relationship to actualmaterial behavior in service.1.4 As a performance test,this method will be used rela-tively infrequently,and to test large lots of material.This testmethod is not intended for routine quality control testing ofgeomembranes.1.5 The values stated in SI units are to be regarded asstandard.The values given in parentheses are for informationonly.1.6 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 limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D76 Specification for Tensile Testing Machines for TextilesD123 Terminology Relating to TextilesD751 Test Methods for Coated FabricsD882 Test Method for Tensile Properties of Thin PlasticSheetingD1593 Specification for Nonrigid Vinyl Chloride PlasticFilm and SheetingD1909 Standard Tables of Commercial Moisture Regainsand Commercial Allowances for Textile FibersD4354 Practice for Sampling of Geosynthetics and RolledErosion Control Products(RECPs)for TestingD4439 Terminology for Geosynthetics3.Terminology3.1 Definitions:3.1.1 atmosphere for testing geomembranes,nair main-tained at a relative humidity of 50 to 70%and a temperatureof 21 6 2C(70 6 4F).3.1.1.1 DiscussionWithin the range of 50 to 70%relativehumidity,moisture content is not expected to affect the tensileproperties of geomembrane materials.In addition,geotextilestandard test methods restrict the range of relative humidity to65 6 5%,while geomembrane standard test methods restrictthe range of relative humidity to 55 6 5%.The restrictedrange in this test method is made broader to reduce the need fortesting laboratories to change laboratory conditions,and con-sidering the lack of expected effect of moisture on geomem-branes.The user should consult Table D1909 to resolvequestions regarding moisture regains of textile fibers,espe-cially if the user is testing a new or unknown material.3.1.2 breaking force,(F),J,nthe force at failure.1This test method is under the jurisdiction of ASTM Committee D35 onGeosynthetics and is the direct responsibility of Subcommittee D35.10 on Geomem-branes.Current edition approved June 1,2011.Published July 2011.Originally approvedin 1988.Last previous edition approved in 2006 as D4885 06.DOI:10.1520/D4885-01R11.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer 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 States1 3.1.3 breaking toughness,T,(FL1),Jm2,nforgeosynthetics,the actual work per unit volume of a materialcorresponding to the breaking force.3.1.3.1 DiscussionBreaking toughness is proportional tothe area under the force-elongation curve from the origin to thebreaking point(see also,work-to-break).Breaking toughness iscalculated from work-to-break and width of a specimen.Ingeomembranes,breaking toughness is often expressed as forceper unit width of material in inch-pound values.In othermaterials,breaking toughness is often expressed as work perunit mass of material.3.1.4 corresponding force,nsynonym for force at speci-fied elongation.3.1.5 elastic limit,nin mechanics,the stress intensity atwhich stress and deformation of a material subjected to anincreasing force cease to be proportional;the limit of stresswithin which a material will return to its original size and shapewhen the force is removed,and hence,not a permanent