ASTM D6836-16
(Test Method)Standard Test Methods for Determination of the Soil Water Characteristic Curve for Desorption Using Hanging Column, Pressure Extractor, Chilled Mirror Hygrometer, or Centrifuge
Standard Test Methods for Determination of the Soil Water Characteristic Curve for Desorption Using Hanging Column, Pressure Extractor, Chilled Mirror Hygrometer, or Centrifuge
SIGNIFICANCE AND USE
5.1 The soil water characteristic curve (SWCC) is fundamental to hydrological characterization of unsaturated soils and is required for most analyses of water movement in unsaturated soils. The SWCC is also used in characterizing the shear strength and compressibility of unsaturated soils. The unsaturated hydraulic conductivity of soil is often estimated using properties of the SWCC and the saturated hydraulic conductivity.
5.2 This method applies only to soils containing two pore fluids: a gas and a liquid. The liquid is usually water and the gas is usually air. Other liquids may also be used, but caution must be exercised if the liquid being used causes excessive shrinkage or swelling of the soil matrix.
5.3 A full investigation has not been conducted regarding the correlation between soil water characteristic curves obtained using this method and soil water characteristics curves of in-place materials. Thus, results obtained from this method should be applied to field situations with caution and by qualified personnel.
Note 1: The quality of the result produced by this standard depends on the competence of the personnel performing the test and the suitability of the equipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable of competent and objective testing, sampling, inspection, etc. Users of this standard are cautioned that compliance with Practice D3740 does not in itself ensure reliable results. Reliable results depend on many factors. Practice D3740 provides a means of evaluating some of these factors.
SCOPE
1.1 These test methods cover the determination of soil water characteristic curves (SWCCs) for desorption (drying). SWCCs describe the relationship between suction and volumetric water content, gravimetric water content, or degree of water saturation. SWCCs are also referred to as soil water retention curves, soil water release curves, or capillary pressure curves.
1.2 This standard describes five methods (A-E) for determining the soil water characteristic curve. Method A (hanging column) is suitable for making determinations for suctions in the range of 0 to 80 kPa. Method B (pressure chamber with volumetric measurement) and Method C (pressure chamber with gravimetric measurement) are suitable for suctions in the range of 0 to 1500 kPa. Method D (chilled mirror hygrometer) is suitable for making determinations for suctions in the range of 500 kPa to 100 MPa. Method E (centrifuge method) is suitable for making determinations in the range 0 to 120 kPa. Method A typically is used for coarse soils with little fines that drain readily. Methods B and C typically are used for finer soils, which retain water more tightly. Method D is used when suctions near saturation are not required and commonly is employed to define the dry end of the soil water characteristic curve (that is, water contents corresponding to suctions >1000 kPa). Method E is typically used for coarser soils where an appreciable amount of water can be extracted with suctions up to 120 kPa. The methods may be combined to provide a detailed description of the soil water characteristic curve. In this application, Method A or E is used to define the soil water characteristic curve at lower suctions (0 to 80 kPa for A, 0 to 120 kPa for E) near saturation and to accurately identify the air entry suction, Method B or C is used to define the soil water characteristic curve for intermediate water contents and suctions (100 to 1000 kPa), and Method D is used to define the soil water characteristic curves at low water contents and higher suctions (>1000 kPa).
1.3 All observed and calculated values shall conform to the guide for significant digits and rounding established in Practice D6026. The procedures in Practice D6026 that are used to specify how data are collected, recorded, and calculated are regarded as the industry standard. In addition, they are represe...
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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: D6836 − 16
Standard Test Methods for
Determination of the Soil Water Characteristic Curve for
Desorption Using Hanging Column, Pressure Extractor,
1
Chilled Mirror Hygrometer, or Centrifuge
This standard is issued under the fixed designation D6836; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 1.3 All observed and calculated values shall conform to the
guideforsignificantdigitsandroundingestablishedinPractice
1.1 Thesetestmethodscoverthedeterminationofsoilwater
D6026. The procedures in Practice D6026 that are used to
characteristic curves (SWCCs) for desorption (drying). SW-
specify how data are collected, recorded, and calculated are
CCs describe the relationship between suction and volumetric
regarded as the industry standard. In addition, they are repre-
water content, gravimetric water content, or degree of water
sentative of the significant digits that should generally be
saturation. SWCCs are also referred to as soil water retention
retained. The procedures do not consider material variation,
curves, soil water release curves, or capillary pressure curves.
purpose for obtaining the data, special purpose studies, or any
1.2 This standard describes five methods (A-E) for deter-
considerations for the objectives of the user. Increasing or
mining the soil water characteristic curve. MethodA(hanging
reducing the significant digits of reported data to be commen-
column) is suitable for making determinations for suctions in
surate with these considerations is common practice. Consid-
the range of 0 to 80 kPa. Method B (pressure chamber with
eration of the significant digits to be used in analysis methods
volumetric measurement) and Method C (pressure chamber
for engineering design is beyond the scope of this standard.
with gravimetric measurement) are suitable for suctions in the
1.4 Units—The values stated in SI units are to be regarded
range of 0 to 1500 kPa. Method D (chilled mirror hygrometer)
asstandard.Nootherunitsofmeasurementareincludedinthis
is suitable for making determinations for suctions in the range
standard.
of 500 kPa to 100 MPa. Method E (centrifuge method) is
suitable for making determinations in the range 0 to 120 kPa. 1.5 This standard does not purport to address all of the
MethodAtypically is used for coarse soils with little fines that safety concerns, if any, associated with its use. It is the
drain readily. Methods B and C typically are used for finer responsibility of the user of this standard to establish appro-
soils, which retain water more tightly. Method D is used when priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use.
suctions near saturation are not required and commonly is
employed to define the dry end of the soil water characteristic
2. Referenced Documents
curve (that is, water contents corresponding to suctions >1000
2
kPa). Method E is typically used for coarser soils where an
2.1 ASTM Standards:
appreciable amount of water can be extracted with suctions up
D421Practice for Dry Preparation of Soil Samples for
to 120 kPa. The methods may be combined to provide a
Particle-Size Analysis and Determination of Soil Con-
3
detailed description of the soil water characteristic curve. In
stants (Withdrawn 2016)
this application, MethodAor E is used to define the soil water
D425Test Method for Centrifuge Moisture Equivalent of
characteristic curve at lower suctions (0 to 80 kPa for A, 0 to
Soils
120kPaforE)nearsaturationandtoaccuratelyidentifytheair
D653Terminology Relating to Soil, Rock, and Contained
entry suction, Method B or C is used to define the soil water
Fluids
characteristic curve for intermediate water contents and suc-
D698Test Methods for Laboratory Compaction Character-
3
tions(100to1000kPa),andMethodDisusedtodefinethesoil
istics of Soil Using Standard Effort (12,400 ft-lbf/ft (600
3
water characteristic curves at low water contents and higher
kN-m/m ))
suctions (>1000 kPa).
1 2
ThesetestmethodsareunderthejurisdictionofASTMCommitteeD18onSoil For referenced ASTM standards, visit the ASTM website, www.astm.org, or
and Rock and are the direct responsibility of Subcommittee D18.04 on Hydrologic contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Properties and Hydraulic Barriers. Standards volume information, refer to the standard’s Document Summary page on
Current edition approved Nov. 15, 2016. Published December 201
...
This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
´2
Designation: D6836 − 02 (Reapproved 2008) D6836 − 16
Standard Test Methods for
Determination of the Soil Water Characteristic Curve for
Desorption Using Hanging Column, Pressure Extractor,
1
Chilled Mirror Hygrometer, or Centrifuge
This standard is issued under the fixed designation D6836; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1
ε NOTE—Mercury warning and other minor changes were editorially added in November 2008.
2
ε NOTE—“1n” was editorially corrected to “ln” in Eq 12 in March 2009.
1. Scope
1.1 These test methods cover the determination of soil water characteristic curves (SWCCs) for desorption (drying). SWCCs
describe the relationship between suction and volumetric water content, gravimetric water content, or degree of water saturation.
SWCCs are also referred to as soil water retention curves, soil water release curves, or capillary pressure curves.
1.2 This standard describes five methods (A-E) for determining the soil water characteristic curve. Method A (hanging column)
is suitable for making determinations for suctions in the range of 0 to 80 kPa. Method B (pressure chamber with volumetric
measurement) and Method C (pressure chamber with gravimetric measurement) are suitable for suctions in the range of 0 to 1500
kPa. Method D (chilled mirror hygrometer) is suitable for making determinations for suctions in the range of 500 kPa to 100 MPa.
Method E (centrifuge method) is suitable for making determinations in the range 0 to 120 kPa. Method A typically is used for
coarse soils with little fines that drain readily. Methods B and C typically are used for finer soils, which retain water more tightly.
Method D is used when suctions near saturation are not required and commonly is employed to define the dry end of the soil water
characteristic curve (that is, water contents corresponding to suctions > 1000 >1000 kPa). Method E is typically used for coarser
soils where an appreciable amount of water can be extracted with suctions up to 120 kPa. The methods may be combined to provide
a detailed description of the soil water characteristic curve. In this application, Method A or E is used to define the soil water
characteristic curve at lower suctions (0 to 80 kPa for A, 0 to 120 kPa for E) near saturation and to accurately identify the air entry
suction, Method B or C is used to define the soil water characteristic curve for intermediate water contents and suctions (100 to
1000 kPa), and Method D is used to define the soil water characteristic curves at low water contents and higher suctions (> 1000
(>1000 kPa).
1.3 All observed and calculated values shall conform to the guide for significant digits and rounding established in Practice
D6026. The procedures in Practice D6026 that are used to specify how data are collected, recorded, and calculated are regarded
as the industry standard. In addition, they are representative of the significant digits that should generally be retained. The
procedures do not consider material variation, purpose for obtaining the data, special purpose studies, or any considerations for
the objectives of the user. Increasing or reducing the significant digits of reported data to be commensurate with these
considerations is common practice. Consideration of the significant digits to be used in analysis methods for engineering design
is beyond the scope of this standard.
1.4 Units—The values stated in SI units are to be regarded as standard. No other units of measurement are included in this
standard.
1.5 Warning—Mercury has been designated by EPA and many state agencies as a hazardous material that can cause central
nervous system, kidney, and liver damage. Mercury, or its vapor, may be hazardous to health and corrosive to materials. Caution
should be taken when handling mercury and mercury-containing products. See the applicable product Material Safety Data Sheet
(MSDS) for details and EPA’s website (http://www.epa.gov/mercury/faq.htm ) for additional information. Users should be aware
that selling mercury or mercury-containing products, or both, in your state may be prohibited by state law.
1
These test methods are under the jurisdiction of ASTM Committee D18 on Soil and Rock and are the direct responsibility of Subcommittee D18.04 on Hydrologic
Properties and Hydraulic Barriers.
Current editio
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