ASTM_D_6836_-_02_2008e2.pdf

Designation:D683602(Reapproved 2008)2Standard Test Methods forDetermination of the Soil Water Characteristic Curve forDesorption Using Hanging Column,Pressure Extractor,Chilled Mirror Hygrometer,or Centrifuge1This standard is issued under the fixed designation D6836;the number immediately following the designation indicates the year oforiginal adoption or,in the case 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.1NOTEMercury warning and other minor changes were editorially added in November 2008.2NOTE“1n”was editorially corrected to“ln”in Eq 12 in March 2009.1.Scope1.1 These test methods cover the determination of soil watercharacteristic curves(SWCCs)for desorption(drying).SW-CCs describe the relationship between suction and volumetricwater content,gravimetric water content,or degree of watersaturation.SWCCs are also referred to as soil water retentioncurves,soil water release curves,or capillary pressure curves.1.2 This standard describes five methods(A-E)for deter-mining the soil water characteristic curve.Method A(hangingcolumn)is suitable for making determinations for suctions inthe range of 0 to 80 kPa.Method B(pressure chamber withvolumetric measurement)and Method C(pressure chamberwith gravimetric measurement)are suitable for suctions in therange of 0 to 1500 kPa.Method D(chilled mirror hygrometer)is suitable for making determinations for suctions in the rangeof 500 kPa to 100 MPa.Method E(centrifuge method)issuitable for making determinations in the range 0 to 120 kPa.Method A typically is used for coarse soils with little fines thatdrain readily.Methods B and C typically are used for finer soilswhich retain water more tightly.Method D is used whensuctions near saturation are not required and commonly isemployed to define the dry end of the soil water characteristiccurve(that is,water contents corresponding to suctions 1000kPa).Method E is typically used for coarser soils where anappreciable amount of water can be extracted with suctions upto 120 kPa.The methods may be combined to provide adetailed description of the soil water characteristic curve.Inthis application,Method A or E is used to define the soil watercharacteristic curve at lower suctions(0 to 80 kPa for A,0 to120 kPa for E)near saturation and to accurately identify the airentry suction,Method B or C is used to define the soil watercharacteristic curve for intermediate water contents and suc-tions(100 to 1000 kPa),and Method D is used to define the soilwater characteristic curves at low water contents and highersuctions(1000 kPa).1.3 All observed and calculated values shall conform to theguide for significant digits and rounding established in PracticeD6026.The procedures in Practice D6026 that are used tospecify how data are collected,recorded,and calculated areregarded as the industry standard.In addition,they are repre-sentative of the significant digits that should generally beretained.The procedures do not consider material variation,purpose for obtaining the data,special purpose studies,or anyconsiderations for the objectives of the user.Increasing orreducing the significant digits of reported data to be commen-surate with these considerations is common practice.Consid-eration of the significant digits to be used in analysis methodsfor engineering design is beyond the scope of this standard.1.4 The values stated in SI units are to be regarded asstandard.No other units of measurement are included in thisstandard.1.5 WarningMercury has been designated by EPA andmany state agencies as a hazardous material that can causecentral nervous system,kidney,and liver damage.Mercury,orits vapor,may be hazardous to health and corrosive tomaterials.Caution should be taken when handling mercury andmercury-containing products.See the applicable product Ma-terial Safety Data Sheet(MSDS)for details and EPAs website(http:/www.epa.gov/mercury/faq.htm)for additional informa-tion.Users should be aware that selling mercury or mercury-containing products,or both,in your state may be prohibited bystate law.1.6 This standard does not purport to address all of thesafety concerns,if any,associated with its use.It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.1These test methods are under the jurisdiction ofASTM Committee D18 on Soiland Rock and are the direct responsibility of Subcommittee D18.04 on HydrologicProperties and Hydraulic Barriers.Current edition approved Sept.1,2008.Published November 2008.Originallyapproved in 2002.Last previous edition approved in 2002 as D6836 02.DOI:10.1520/D6836-02R08E02.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 2.Referenced Documents2.1 ASTM Standards:2D421 Practice for Dry Preparation of