ASTM_D_7737_-_D_7737M_-_15.pdf

Designation:D7737/D7737M15Standard Test Method forIndividual Geogrid Junction Strength1This standard is issued under the fixed designation D7737/D7737M;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 is an index test which provides aprocedure for determining the strength of an individual geogridjunction,also called a node.The test is configured such that asingle rib is pulled from its junction with a rib(s)transverse tothe test direction to obtain the maximum force,or strength ofthe junction.The procedure allows for the use of two differentclamps with the appropriate clamp selected to minimize theinfluence of the clamping mechanism on the specific type ofgeogrid to be tested.1.2 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.1.3 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:2D4354 Practice for Sampling of Geosynthetics and RolledErosion Control Products(RECPs)for TestingD4439 Terminology for GeosyntheticsD5262 Test Method for Evaluating the Unconfined TensionCreep and Creep Rupture Behavior of Geosynthetics3.Terminology3.1 Definitions:Definitions of other terms applying to thistest method appear in Terminology D4439.3.1.1 atmosphere for testing geosynthetics,nair main-tained at a relative humidity of 50 to 70%and a temperatureof 21 6 2C 70 6 4F.3.1.2 breaking force,(F),nthe force at failure.3.1.3 geogrid,na geosynthetic formed by a regular net-work of integrally connected elements with apertures greaterthan 6.35 mm 0.25 in.to allow interlocking with surroundingsoil,rock,earth,and other surrounding materials to primarilyfunction as reinforcement.D52623.1.4 index test,na test procedure which may containknown bias,but which may be used to establish an order for aset of specimens with respect to the property of interest.3.1.5 integral,adjin geosynthetics,forming a necessarypart of the whole;a constituent.3.1.6 junction,nthe point where geogrid ribs are intercon-nected to provide structure and dimensional stability.3.1.7 rib,nfor geogrids,the continuous elements of ageogrid which are either in the machine or cross-machinedirection as manufactured.3.1.8 rupture,nfor geogrids,the breaking or tearing apartof ribs.4.Summary of Test Method4.1 This standard proposes a test method for performingtension tests on geogrid junctions.The procedure provides twoclamping techniques for the junction to be tested including:MethodAin which the clamps firmly grip the ribs transverse tothe test direction on each side of the junction;and,Method Bin which the ribs transverse to the test direction are constrainedin a slot,constraining rotation of the junction,while the rib inthe test direction passes through the slot without the junctionclamp applying confinement to the junction.The junctionclamping technique is selected for the specific type of geogridin order to minimize rotation and corresponding peal of thejunction during the test.The rib in the test direction goingthrough the junction is then clamped at a distance from thejunction and the system tensioned until junction(or rib)failureoccurs.This forces a tension or shear force to occur within thejunction in the direction of the applied load.The junction hasno normal pressure on it,that is,it is horizontally unconfined.1This 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 July 1,2015.Published September 2015.Originallyapproved in 2011.Last previous edition approved in 2011 as D773711.DOI:10.1520/D7737_D7737M-152For 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 5.Significance and Use5.1 This index test method is to be used to determine thestrength of an individual junction in a geogrid product.The testis performed in isolation,while in service the junction istypically confined.Thus the results from this test method arenot anticipated to be related to design performance.5.2