ASTM_D_7748_-_D_7748M_-_14.pdf

Designation:D7748/D7748M14Standard Test Method forFlexural Rigidity of Geogrids,Geotextiles and RelatedProducts1This standard is issued under the fixed designation D7748/D7748M;the number immediately following the designation indicates theyear of original adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of lastreapproval.A superscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope1.1 This test method covers the measurement of stiffnessproperties of geogrids,geotextiles and geogrid-geotextile com-posites all of which are referred to as geosynthetics within thistest method.Bending length is measured and flexural rigidity iscalculated through use of the cantilever test procedure.1.1.1 This test method employs the principle of cantileverbending of the geosynthetic under its own mass.1.2 This test method applies to geogrids,geotextiles andgeogrid-geotextile composites.1.3 This test method is for manufacturing quality controlpurposes only,to ensure uniformity and consistency of flexuralrigidity for a specific product from roll to roll and lot to lot.1.4 The values stated in either SI units or inch-pound unitsare to be regarded separately as standard.The values stated ineach system may not be exact equivalents;therefore,eachsystem shall be used independently of the other.Combiningvalues from the two systems may result in non-conformancewith the standard.1.5 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:2D123 Terminology Relating to TextilesD1776 Practice for Conditioning and Testing TextilesD4354 Practice for Sampling of Geosynthetics and RolledErosion Control Products(RECPs)for TestingD4439 Terminology for GeosyntheticsE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test Method3.Terminology3.1 For common definitions of terms in this test method,refer to Terminology D123 and Terminology D4439.3.2 Definitions of Terms Specific to This Standard:3.2.1 bending length,na measure of the interaction be-tween geosynthetic weight and geosynthetic stiffness as shownby the way in which a geosynthetic bends under its ownweight.3.2.1.1 DiscussionBending length reflects the stiffness ofa geosynthetic when bent in one plane under the force ofgravity.4.Summary of Test Method4.1 A specimen is slid at a specified rate in a directionparallel to its long dimension,until its leading edge projectsfrom the edge of a horizontal surface.The length of theoverhang is measured when the tip of the specimen is de-pressed under its own mass to the point where the line joiningthe top to the edge of the platform makes a 0.724 radians41.5 angle with the horizontal.From this measured length,the bending length and flexural rigidity are calculated.5.Significance and Use5.1 This test method is considered satisfactory for manufac-turing quality control testing of a specific geosynthetic;however,caution is advised since information about between-laboratory precision is incomplete.Comparative tests as di-rected in 5.1.1 may be advisable.5.1.1 In case of a dispute arising from differences inreported test results when using this test method for acceptancetesting of commercial shipments,the purchaser and 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 as homogeneous as possible and that are1This 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 edition approved Jan.1,2014.Published January 2014.Originallyapproved in 2012.Last previous edition approved in 2013 as D7748/D7748M13.DOI:10.1520/D7748_D7748M14.2For 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 from a lot of material of the type in question.Test specimensshould then be randomly assigned in equal numbers to eachlaboratory for testing.The average results from the twolaboratories should be compared using the appropriate statis-tical analysis and an acceptable probability level chosen by thetwo parties before testing is begun.If a bias is found,either itscause must be found and corrected or the purchaser and thesup