ASTM_D_6767_-_16.pdf

Designation:D676716Standard Test Method forPore Size Characteristics of Geotextiles by Capillary FlowTest1This standard is issued under the fixed designation D6767;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 poresize distribution of geotextile filters with pore sizes rangingfrom 1 to 1000 m.NOTE1The accuracy of this procedure has been verified up to amaximum pore size of 500 m.Above this value accuracy has been foundto be equipment dependent and should be verified by the user throughchecks on materials with known opening sizes.1.2 The test method measures the entire pore size distribu-tion in terms of a surface analysis of specified pore sizes in ageotextile,defined in terms of the limiting diameters.1.3 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.4 This standard may involve hazardous materials,operations,and equipment.This standard does not purport toaddress all of the safety concerns,if any,associated with itsuse.It is the responsibility of the user of this standard toestablish appropriate safety and health practices and deter-mine the applicability of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2D1129 Terminology Relating to WaterD1193 Specification for Reagent WaterD4354 Practice for Sampling of Geosynthetics and RolledErosion Control Products(RECPs)for TestingD4439 Terminology for Geosynthetics3.Terminology3.1 DefinitionsFor definitions of other terms used in thistest method,refer to Terminologies D4439 and D1129.3.2 Definitions of Terms Specific to This Standard:3.2.1 bubble point pore size(O98),nthe largest effectivepore diameter detected by the sudden increase of flow rate atthe beginning of the wet test.3.2.2 pore constriction(O),ndiameter of a circle havingthe same area as the smallest section of a given pore.3.2.3 pore size(Oi),ncapillary equivalent pore diameterfor which the percent of total pore diameters i in a givengeotextile based on the surface occupied by the pores aresmaller than or equal to that diameter.3.2.4 pore size distribution(PSD),npercent cumulativedistribution of the complete range of pore sizes with in a givengeotextile based on the surface occupied by the pores.3.2.5 wetting fluid,nfluid used to wet the geotextile testspecimen for the capillary porometry portion of the testmethod,that is,the“wet”test.The verb“wet”is intended tomean to completely saturate the geotextile specimen with thewetting fluid thoroughly such that the entire thickness of thespecimen contains fluid with no entrained air bubbles.4.Summary of Test Method4.1 Geotextile filters have discrete pores from one side tothe other of the geotextile.The bubble point test is based on theprinciple that a wetting fluid is held in these continuous poresby capillary attraction and surface tension,and the minimumpressure required to force fluid from these pores is a functionof pore diameter.4.2 A fluid-wet geotextile will pass air when the applied airpressure exceeds the capillary attraction of the fluid in the poreconstriction.Smaller pore constrictions will exhibit similarbehavior at higher pressures.The relationship between poresize and pressure has been established for the wetting fluid.4.3 By comparing the gas flow rates of both a wet and drytest at the same pressures,the percentage of the flow passingthrough the filter pores larger than or equal to the specified sizemay be calculated from the pressure-size relationship.Byincreasing pressure in small steps,it is possible to determinethe flow contribution of very small pore size increments bydifference.1This test method is under the jurisdiction of ASTM Committee D35 onGeosynthetics and is the direct responsibility of Subcommittee D35.03 on Perme-ability and Filtration.Current edition approved Sept.1,2016.Published October 2016.Originallyapproved in 2002.Last previous edition approved in 2014 as D6767 14.DOI:10.1520/D6767-16.2For 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 5.Significance and Use5.1 This test method may be used to:5.1.1 Determine the pore size distribution of a geotextile,5.1.2 Determine the maximum pore size of a geotextile,5.1.3 Determine the mean flow pore size of a geotextile,5.1.4 Determine the effect of processes such as calendaringor needle punching upon the pore size distribution,5.1.5 Determine the effect of compression upon the poresize distrib