Designation:D1883−16StandardTestMethodforCaliforniaBearingRatio(CBR)ofLaboratory-CompactedSoils1ThisstandardisissuedunderthefixeddesignationD1883;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.ThisstandardhasbeenapprovedforusebyagenciesoftheU.S.DepartmentofDefense.1.Scope*1.1ThistestmethodcoversthedeterminationoftheCali-forniaBearingRatio(CBR)ofpavementsubgrade,subbase,andbasecoursematerialsfromlaboratorycompactedspeci-mens.Thetestmethodisprimarilyintendedfor,butnotlimitedto,evaluatingthestrengthofmaterialshavingmaximumparticlesizelessthan3⁄4in.(19mm).1.2Whenmaterialshavingamaximumparticlesizegreaterthan3⁄4in.(19mm)aretobetested,thistestmethodprovidesformodifyingthegradationofthematerialsothatthematerialusedfortestingallpassesthe3⁄4-in.(19-mm)sievewhilethetotalgravelfraction(materialpassingthe3-in.(75-mm)sieveandretainedontheNo.4(4.75-mm)sieve)remainsthesame.WhiletraditionallythismethodofspecimenpreparationhasbeenusedtoavoidtheerrorinherentintestingmaterialscontaininglargeparticlesintheCBRtestapparatus,themodifiedmaterialmayhavesignificantlydifferentstrengthpropertiesthantheoriginalmaterial.However,alargeexperi-encedatabasehasbeendevelopedusingthistestmethodformaterialsforwhichthegradationhasbeenmodified,andsatisfactorydesignmethodsareinusebasedontheresultsoftestsusingthisprocedure.1.3PastpracticehasshownthatCBRresultsforthosematerialshavingsubstantialpercentagesofparticlesretainedontheNo.4(4.75mm)sievearemorevariablethanforfinermaterials.Consequently,moretrialsmayberequiredforthesematerialstoestablishareliableCBR.1.4ThistestmethodprovidesforthedeterminationoftheCBRofamaterialatoptimumwatercontentorarangeofwatercontentfromaspecifiedcompactiontestandaspecifieddryunitweight.ThedryunitweightisusuallygivenasapercentageofmaximumdryunitweightdeterminedbyTestM...
