Designation:D7928−21´1StandardTestMethodforParticle-SizeDistribution(Gradation)ofFine-GrainedSoilsUsingtheSedimentation(Hydrometer)Analysis1ThisstandardisissuedunderthefixeddesignationD7928;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.ε1NOTE—SummaryofChangessectionwaseditoriallyaddedinJune2021.1.Scope*1.1Thistestmethodcoversthequantitativedeterminationofthedistributionofparticlesizesofthefine-grainedportionofsoils.Thesedimentationbyhydrometermethodisusedtodeterminetheparticle-sizedistribution(gradation)ofthematerialthatisfinerthantheNo.200(75-µm)sieveandlargerthanabout0.2-µm.ThetestisperformedonmaterialpassingtheNo.10(2.0-mm)orfinersieveandtheresultsarepresentedasthemasspercentfinerofthisfractionversusthelogoftheparticlediameter.1.2Thismethodcanbeusedtoevaluatethefine-grainedfractionofasoilwithawiderangeofparticlesizesbycombiningthesedimentationresultswithresultsfromasieveanalysisusingD6913toobtainthecompletegradationcurve.Themethodcanalsobeusedwhentherearenocoarse-grainedparticlesorwhenthegradationofthecoarse-grainedmaterialisnotrequiredornotneeded.NOTE1—Thesignificantdigitsrecordedinthistestmethodprecludeobtainingthegrainsizedistributionofmaterialsthatdonotcontainasignificantamountoffines.Forexample,cleansandswillnotyielddetectableamountsofsiltandclaysizedparticles,andthereforeshouldnotbetestedwiththismethod.Theminimumamountoffinesinthesedimentationspecimenis15g.1.3Whencombiningtheresultsofthesedimentationandsievetests,theprocedureforobtainingthematerialforthesedimentationanalysisandcalculationsforcombiningtheresultswillbeprovidedbythemoregeneraltestmethod,suchasTestMethodsD6913(Note2).NOTE2—SubcommitteeD18.03iscurrentlydevelopinganewtestmethod“TestMethodforParticle-SizeAnalysisofSoilsCombiningtheSieveandSedimentationTechniques.”1.4Theterms“s...
