Designation:D2487−11StandardPracticeforClassificationofSoilsforEngineeringPurposes(UnifiedSoilClassificationSystem)1ThisstandardisissuedunderthefixeddesignationD2487;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.ThisstandardhasbeenapprovedforusebyagenciesoftheU.S.DepartmentofDefense.1.Scope*1.1Thispracticedescribesasystemforclassifyingmineralandorgano-mineralsoilsforengineeringpurposesbasedonlaboratorydeterminationofparticle-sizecharacteristics,liquidlimit,andplasticityindexandshallbeusedwhenpreciseclassificationisrequired.NOTE1—Useofthisstandardwillresultinasingleclassificationgroupsymbolandgroupnameexceptwhenasoilcontains5to12%finesorwhentheplotoftheliquidlimitandplasticityindexvaluesfallsintothecrosshatchedareaoftheplasticitychart.Inthesetwocases,adualsymbolisused,forexample,GP-GM,CL-ML.Whenthelaboratorytestresultsindicatethatthesoilisclosetoanothersoilclassificationgroup,theborderlineconditioncanbeindicatedwithtwosymbolsseparatedbyaslash.Thefirstsymbolshouldbetheonebasedonthisstandard,forexample,CL/CH,GM/SM,SC/CL.Borderlinesymbolsareparticularlyusefulwhentheliquidlimitvalueofclayeysoilsiscloseto50.Thesesoilscanhaveexpansivecharacteristicsandtheuseofaborderlinesymbol(CL/CH,CH/CL)willalerttheuseroftheassignedclassificationsofexpansivepotential.1.2Thegroupsymbolportionofthissystemisbasedonlaboratorytestsperformedontheportionofasoilsamplepassingthe3-in.(75-mm)sieve(seeSpecificationE11).1.3Asaclassificationsystem,thisstandardislimitedtonaturallyoccurringsoils.NOTE2—Thegroupnamesandsymbolsusedinthistestmethodmaybeusedasadescriptivesystemappliedtosuchmaterialsasshale,claystone,shells,crushedrock,etc.SeeAppendixX2.1.4Thisstandardisforqualitativeapplicationonly.NOTE3—Whenquantitativeinformationisrequiredfordetaileddesignsofimportantstructures,thistestmethod...
