Designation:D4944−18StandardTestMethodforFieldDeterminationofWater(Moisture)ContentofSoilbytheCalciumCarbideGasPressureTester1ThisstandardisissuedunderthefixeddesignationD4944;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginaladoptionor,inthecaseofrevision,theyearoflastrevision.Anumberinparenthesesindicatestheyearoflastreapproval.Asuperscriptepsilon(´)indicatesaneditorialchangesincethelastrevisionorreapproval.1.Scope*1.1Thistestmethodoutlinesproceduresfordeterminingthewater(moisture)contentofsoilbychemicalreactionusingcalciumcarbideasareagenttoreactwiththeavailablewaterinthesoilproducingagas.Ameasurementismadeofthegaspressureproducedwhenaspecifiedmassofwetormoistsoilisplacedinatestingdevicewithanappropriatevolumeofreagentandmixed.1.2ThistestmethodisnotintendedasareplacementforTestMethodD2216;butasasupplementwhenrapidresultsarerequired,whentestingisdoneinfieldlocations,orwhereanovenisnotpracticalforuse.TestMethodD2216istobeusedasthetestmethodtocompareforaccuracychecksandcorrection.1.3Thistestmethodisapplicableformostsoils.Calciumcarbide,usedasareagent,reactswithwaterasitismixedwiththesoilbyshakingandagitatingwiththeaidofsteelballsintheapparatus.Toproduceaccurateresults,thereagentmustreactwithallthewaterwhichisnotchemicallyhydratedwithsoilmineralsorcompoundsinthesoil.Somehighlyplasticclaysoilsorothersoilsnotfriableenoughtobreakupmaynotproducerepresentativeresultsbecausesomeofthewatermaybetrappedinsidesoilclodsorclumpswhichcannotcomeincontactwiththereagent.Theremaybesomesoilscontainingcertaincompoundsorchemicalsthatwillreactunpredictablywiththereagentandgiveerroneousresults.AnysuchproblemwillbecomeevidentascalibrationorchecktestswithTestMethodD2216aremade.Somesoilscontainingcompoundsormineralsthatdehydratewithheat(suchasgypsum)whicharetohavespecialtemperaturecontrolwithTestMethodD2216maynotbeaffected(dehydrated)inthistestmethod.1.4Thistestmethodislimitedtousingcalciumcarbidemoisturetestequipmentmadefor20g,orlarger,soilspeci-mensandtotestingsoilw...
