1、Designation:D494418Standard Test Method forField Determination of Water(Moisture)Content of Soil bythe Calcium Carbide Gas Pressure Tester1This standard is issued under the fixed designation D4944;the number immediately following the designation indicates the year oforiginal adoption or,in the case
2、of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript epsilon()indicates an editorial change since the last revision or reapproval.1.Scope*1.1 This test method outlines procedures for determining thewater(moisture)content of soil by chemical
3、 reaction usingcalcium carbide as a reagent to react with the available waterin the soil producing a gas.A measurement is made of the gaspressure produced when a specified mass of wet or moist soilis placed in a testing device with an appropriate volume ofreagent and mixed.1.2 This test method is no
4、t intended as a replacement forTest Method D2216;but as a supplement when rapid results arerequired,when testing is done in field locations,or where anoven is not practical for use.Test Method D2216 is to be usedas the test method to compare for accuracy checks andcorrection.1.3 This test method is
5、applicable for most soils.Calciumcarbide,used as a reagent,reacts with water as it is mixed withthe soil by shaking and agitating with the aid of steel balls inthe apparatus.To produce accurate results,the reagent mustreact with all the water which is not chemically hydrated withsoil minerals or com
6、pounds in the soil.Some highly plasticclay soils or other soils not friable enough to break up may notproduce representative results because some of the water maybe trapped inside soil clods or clumps which cannot come incontact with the reagent.There may be some soils containingcertain compounds or
7、 chemicals that will react unpredictablywith the reagent and give erroneous results.Any such problemwill become evident as calibration or check tests with TestMethod D2216 are made.Some soils containing compounds orminerals that dehydrate with heat(such as gypsum)which areto have special temperature
8、 control with Test Method D2216may not be affected(dehydrated)in this test method.1.4 This test method is limited to using calcium carbidemoisture test equipment made for 20 g,or larger,soil speci-mens and to testing soil which contains particles no larger thanthe 4.75 mm(No.4)Standard sieve size.1.
9、5 The values stated in SI units are to be regarded asstandard.The inch-pound units given in parentheses aremathematical conversions,which are provided for informationpurposes only and are not considered standard.1.5.1 Cited sieve sizes are the standard sieve sizes given inTable 1 of Specification E1
10、1.1.6 All observed and calculated values shall conform to theguidelines for significant digits and rounding established inPractice D6026 unless superseded by this standard.1.6.1 The procedures used to specify how data are collected,recorded or calculated in this standard are regarded as theindustry
11、standard.In addition they are representative of thesignificant digits that generally should be retained.The proce-dures used do not consider material variation,purpose forobtaining the data,special purpose studies,or any consider-ations for the users objectives;it is common practice toincrease or re
12、duce significant digits of reported data to becommensurate with these considerations.It is beyond the scopeof this standard to consider significant digits used in analyticalmethods for engineering design.1.7 This standard does not purport to address all of thesafety concerns,if any,associated with i
13、ts use.It is theresponsibility of the user of this standard to establish appro-priate safety,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.For specific hazards statements,see Section 7.1.8 This international standard was developed in accor
14、-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Sta
15、ndards:2D653 Terminology Relating to Soil,Rock,and ContainedFluids1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.08 on Special andConstruction Control Tests.Current edition approved Feb.15,2018.Published February
16、2018.Originallyapproved in 1989.Last previous edition approved in 2011 as D4944 11.DOI:10.1520/D4944-18.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.Un