Designation:D6780/D6780M−19StandardTestMethodsforWaterContentandDensityofSoilInsitubyTimeDomainReflectometry(TDR)1ThisstandardisissuedunderthefixeddesignationD6780/D6780M;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope*1.1ThistestmethodmaybeusedtodeterminethewatercontentofsoilsandthedensityofsoilsinplaceusingTimeDomainReflectometry.1.2Thistestmethodappliestosoilsthathave30%orlessbyweightoftheirparticlesretainedonthe19.0-mm[3⁄4-in.]sieve.1.3Thistestmethodissuitableforuseasameansofacceptanceforcompactedfillorembankments.1.4Thistestmethodisnotappropriateforfrozensoilsorsoilsattemperaturesover40°C[100°F]andmaynotbesuitablefororganicsoils,highlyplasticsoils,orextremelydensesoils.1.5AllobservedandcalculatedvaluesshallconformtotheguidelinesforsignificantdigitsandroundingestablishedinPracticeD6026.1.5.1Themethodusedtospecifyhowdataarecollected,calculated,orrecordedinthisstandardisnotdirectlyrelatedtotheaccuracytowhichthedatacanbeappliedindesignorotheruses,orboth.Howoneappliestheresultsobtainedusingthisstandardisbeyonditsscope.21.6Twoalternativeproceduresareprovidedtodeterminethewatercontentandthedensityofsoilinsitu:1.6.1ProcedureAinvolvestwotestsinthefield,aninsitutestandatestinamoldcontainingmaterialexcavatedfromtheinsitutestlocation.Theapparentdielectricconstantisdeter-minedinbothtests.1.6.2ProcedureBinvolvesonlyaninsitutestbyincorpo-ratingthefirstvoltagedropandlongtermvoltage(V1andVf)inadditiontotheapparentdielectricconstant.Whilethebulkelectricalconductivitycanbedeterminedfromthesemeasurements,itisnotneededforthedeterminationofwatercontentanddensity.1.7Units—ThevaluesstatedineitherSIunitsorinch-poundunitsaretoberegardedseparatelyasstandard.Thevaluesstatedineachsystemmaynotbeexactequivalents;therefore,eachsystemshallbeusedindependentlyoftheother.Comb...
