ASTM D6539-00(2006)e2
(Test Method)Standard Test Method for Measurement of Pneumatic Permeability of Partially Saturated Porous Materials by Flowing Air
Standard Test Method for Measurement of Pneumatic Permeability of Partially Saturated Porous Materials by Flowing Air
SIGNIFICANCE AND USE
This test method applies to the one-dimensional laminar (viscous) flow of air in porous materials such as soil.
Note 1—This test method deals with porous materials with both gaseous (air) and liquid (pore water) mobile fluids: The liquid phase is much less compressible, has a higher viscosity, and is much more tightly bound to the solid phase by chemical forces. The assumption of single-phase flow may still be presumed to be valid since the test gradient ensuring the conditions of laminar flow may be low enough that flow of the liquid phase is negligible.
The degree of saturation of the specimen shall be less than that which would produce significant internal transport of pore water or alter the continuity of air voids under the applied pneumatic gradients. The maximum permissible degree of saturation must be evaluated by an experienced analyst. In no instance shall the specimen be so saturated that pore water appears at the exit of the permeameter cell during the test.
This test method is based on the assumption that the rate of mass flow through the specimen is constant with time.
Note 2—When a specimen contains volatile materials this assumption is violated. The mass of gas flowing out will be greater than that flowing in, the pneumatic gradient is indeterminate and the test may become meaningless. Such specimens pose special problems and must be decontaminated before analysis in order to minimize health and safety concerns and to prevent contamination of the test apparatus.
The pneumatic permeability of porous materials may be strongly dependent on a variety of physical properties including the void ratio, the degree of saturation, percent and direction of compaction, and so forth. It is beyond the scope of this test method to elaborate these dependencies. Rather, this test method is intended to be a measurement technique for determining the pneumatic permeability under a certain set of laboratory conditions. It is the responsibility of the requestor...
SCOPE
1.1 This test method covers laboratory determination of the coefficient of permeability for the flow of air (pneumatic permeability) through partially saturated porous materials.
1.2 This test method may be used with undisturbed or compacted coarse grained soils, silts, or lean cohesive soils that have a low degree of saturation and that have pneumatic permeability between 0.001 square micrometre (1.01 millidarcy) and 100 square micrometre (101 darcy).
1.3 The values stated in SI units are to be regarded as the standard, unless other units are specifically given. By tradition in U.S. practice, the pneumatic permeability of porous media is reported in units of darcy, although the SI unit for pneumatic permeability is square metre.
1.4 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
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Standards Content (Sample)
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Contact ASTM International (www.astm.org) for the latest information
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Designation: D6539 − 00(Reapproved 2006)
Standard Test Method for
Measurement of Pneumatic Permeability of Partially
Saturated Porous Materials by Flowing Air
This standard is issued under the fixed designation D6539; 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.
´ NOTE—Mercury warning editorially added in March 2008.
´ NOTE— Editorially moved mercury warning to follow Section 5.3.1 in May 2008.
1. Scope D1557Test Methods for Laboratory Compaction Character-
istics of Soil Using Modified Effort (56,000 ft-lbf/ft
1.1 This test method covers laboratory determination of the
(2,700 kN-m/m ))
coefficient of permeability for the flow of air (pneumatic
D1557Test Methods for Laboratory Compaction Character-
permeability) through partially saturated porous materials.
istics of Soil Using Modified Effort (56,000 ft-lbf/ft
1.2 This test method may be used with undisturbed or
(2,700 kN-m/m ))
compactedcoarsegrainedsoils,silts,orleancohesivesoilsthat
D2216Test Methods for Laboratory Determination ofWater
have a low degree of saturation and that have pneumatic
(Moisture) Content of Soil and Rock by Mass
permeability between 0.001 square micrometre (1.01 milli-
D3550Practice for Thick Wall, Ring-Lined, Split Barrel,
darcy) and 100 square micrometre (101 darcy).
Drive Sampling of Soils
1.3 The values stated in SI units are to be regarded as the D3740Practice for Minimum Requirements for Agencies
Engaged in Testing and/or Inspection of Soil and Rock as
standard, unless other units are specifically given. By tradition
inU.S.practice,thepneumaticpermeabilityofporousmediais Used in Engineering Design and Construction
D4220 Practices for Preserving and Transporting Soil
reported in units of darcy, although the SI unit for pneumatic
permeability is square metre. Samples
D4525Test Method for Permeability of Rocks by Flowing
1.4 This standard does not purport to address all of the
Air
safety concerns, if any, associated with its use. It is the
D4564Test Method for Density and Unit Weight of Soil in
responsibility of the user of this standard to establish appro-
Place by the Sleeve Method
priate safety and health practices and determine the applica-
D4753Guide for Evaluating, Selecting, and Specifying Bal-
bility of regulatory limitations prior to use.
ances and Standard Masses for Use in Soil, Rock, and
Construction Materials Testing
2. Referenced Documents
D4767Test Method for Consolidated Undrained Triaxial
2.1 ASTM Standards:
Compression Test for Cohesive Soils
D653Terminology Relating to Soil, Rock, and Contained
D5084Test Methods for Measurement of Hydraulic Con-
Fluids
ductivity of Saturated Porous Materials Using a Flexible
D698Test Methods for Laboratory Compaction Character-
Wall Permeameter
istics of Soil Using Standard Effort (12 400 ft-lbf/ft (600
D5856Test Method for Measurement of Hydraulic Conduc-
kN-m/m ))
tivity of Porous Material Using a Rigid-Wall,
D854Test Methods for Specific Gravity of Soil Solids by
Compaction-Mold Permeameter
Water Pycnometer
E1Specification for ASTM Liquid-in-Glass Thermometers
E145 Specification for Gravity-Convection and Forced-
Ventilation Ovens
ThistestmethodisunderthejurisdictionofASTMCommitteeD18onSoiland
Rock and is the direct responsibility of Subcommittee D18.04 on Hydrologic
Properties and Hydraulic Barriers.
3. Terminology
Current edition approved Feb. 1, 2006. Published March 2006. Originally
3.1 Definitions of Terms Specific to This Standard:
approved in 2000. Last previous edition approved in 2000 as D6539–00. DOI:
10.1520/D6539-00R06E02.
3.1.1 darcy—a porous medium has a permeability of one
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
darcy when a single-phase fluid of 1-MPa·s (1-cP) viscosity
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
that completely fills the voids of the medium will flow through
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. it under conditions of laminar (viscous) flow at a rate of 1
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D6539 − 00 (2006)
TABLE 1 Viscosity of Air, µ, as a Function of Temperature meaningless. Such specimens pose special problems and must be decon-
taminated before analysis in order to minimize health and safety concerns
Temperature, °C Viscosity, Pa·s
−5
and to prevent contamination of the test apparatus.
12 1.778 × 10
−5
14 1.788 × 10
−5
4.4 The pneumatic permeability of porous materials may be
16 1.798 × 10
−5
18 1.808 × 10
strongly dependent on a variety of physical properties includ-
−5
20 1.818 × 10
−5 ing the void ratio, the degree of saturation, percent and
22 1.828 × 10
−5
24 1.837 × 10 directionofcompaction,andsoforth.Itisbeyondthescopeof
−5
26 1.847 × 10
this test method to elaborate these dependencies. Rather, this
−5
28 1.857 × 10
test method is intended to be a measurement technique for
determining the pneumatic permeability under a certain set of
laboratoryconditions.Itistheresponsibilityoftherequestorto
3 2
specify which soil parameters must be controlled to ensure a
cm /s/cm of cross-sectional area under a pressure gradient of
valid extension of the test results to field conditions.
1.013 × 10 Pa (1 atm)/cm. (One darcy = 0.9869 square micro
metre.)
4.5 It is assumed that Darcy’s Law is valid. The validity of
3.1.2 effective confining stress, (Flexible Wall Method
Darcy’s law may be evaluated by plotting the volumetric flow
only)—the difference between the permeameter cell confining
through the specimen against the differential pressure drop
pressure and the mean specimen pore-air-water pressures.
across the specimen. If the individual test points lie within
3.1.2.1 The effective confining stress is assumed to be
25%ofastraightlinepassingthroughtheorigin,thenDarcy’s
distributed as a radial vector exhibiting a linear gradient along
law may be taken as valid.
the length of the specimen with a minimum at the inlet and a
maximum at the outlet. NOTE 3—Darcy’s law is valid only when saturation does not change
over time. Long measurement times associated with the use of bubble
3.1.2.2 For the purposes of this test method, the effective
meters and manometers may indirectly be an uncontrolled source of
confining stress is stated as a scalar value and calculated as the
variability when plotting flow versus pressure drop (see 8.2). The
confining gage pressure minus the average of the specimen
recommended use of digital electronic flow and pressure sensors leads to
inlet and outlet gage pressures.
considerably reduced measurement times because the user can quickly
3.1.3 gage pressure—pressure measured relative to ambient
determine by inspection when a steady state condition has been reached.
atmospheric pressure.
At that point only a single reading needs to be taken for a reliable
measurement. A rapid course of measurement will minimize dehydration
3.1.4 pneumatic permeability—the capacity of a porous
of partially saturated specimens.
medium to conduct gas in the presence of a gas (air) pressure
NOTE4—Humidifyingthetestgastominimizespecimendehydrationis
gradient measured as the ratio of volumetric flow through a
not recommended because: (1) there is no practical way to either measure
specimen to the resultant pressure drop across it. Also com-
or control the relative humidity of the test gas, either at the inlet or outlet
monlyknownaspneumaticconductivityorpermeabilitytoair.
of the specimen; (2) the calibration of the electronic flowmeter is for dry
air only and would become unreliable in the presence of water vapor,
3.2 For definitions of other terms used in this test method,
especially in view of the potential for irreversible adsorption of moisture
see Terminology D653.
on the sensor elements; (3) there is a danger of permanent water
condensationinthestatictransferlinesandotherapparatusdeadvolumes;
4. Significance and Use
and (4) the test apparatus would become more complex and difficult to
use.
4.1 Thistestmethodappliestotheone-dimensionallaminar
(viscous) flow of air in porous materials such as soil.
4.6 Thistestmethodcoverstheuseoftwodifferenttypesof
permeameter cells, flexible wall and rigid wall, and two types
NOTE 1—This test method deals with porous materials with both
gaseous (air) and liquid (pore water) mobile fluids: The liquid phase is
of air flow regulation, mass flow control and pressure control.
much less compressible, has a higher viscosity, and is much more tightly
bound to the solid phase by chemical forces. The assumption of single-
4.7 A flexible wall permeameter is the preferred means for
phase flow may still be presumed to be valid since the test gradient
confining the test specimen in accordance with Test Methods
ensuring the conditions of laminar flow may be low enough that flow of
D5084, D4525, and D4767. This test method may be per-
the liquid phase is negligible.
formed using a rigid wall permeameter and all reference to
4.2 The degree of saturation of the specimen shall be less
effective confining stress and the permeameter cell pressure
than that which would produce significant internal transport of
system shall be disregarded.
porewateroralterthecontinuityofairvoidsundertheapplied
pneumatic gradients. The maximum permissible degree of
4.8 Forsomespecimens,thepneumaticpermeabilitywillbe
saturation must be evaluated by an experienced analyst. In no
strongly dependent on the effective confining stress due to
instance shall the specimen be so saturated that pore water
porosity reduction. Whenever possible, the requestor should
appears at the exit of the permeameter cell during the test.
specify the field overburden conditions at which this test
4.3 Thistestmethodisbasedontheassumptionthattherate method is to be performed. In some specimens, this stress will
vary significantly with flow in an indeterminate way. All
of mass flow through the specimen is constant with time.
specimens should be evaluated for this effect by performing
NOTE 2—When a specimen contains volatile materials this assumption
thistestmethodattwoormoredifferentconfiningstressvalues
is violated. The mass of gas flowing out will be greater than that flowing
in, the pneumatic gradient is indeterminate and the test may become when a flexible wall permeameter is used.
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D6539 − 00 (2006)
4.9 This test method is intended to support soil remediation 5.1.1.2 Be free of particulate matter greater than 5 µm in
operations such as: soil vapor extraction, air sparging, back- diameter, and
filling of soils in utility trenches, and similar engineering 5.1.1.3 Beprovidedwithamonitoringgageandregulatorto
activities. deliver a pressure of at least 350 6 5 kPa (50 6 1 psi).
4.10 The correlation between results obtained with this test
NOTE 6—Other gases than air may be used when specified by the
requestor. It is important that the electronic flowmeter is calibrated for the
method and in situ field measurements has only been partially
test gas. Nitrogen is often preferred as having more uniform viscosity and
established.Thesmalllaboratoryspecimenusedinthismethod
low water content.
may not be representative of the distributed condition on-site
5.1.2 Flow Control— The flow rate of air shall be regulated
due to vadose zone fluctuations, changes in soil stratigraphy,
upstream from the specimen by a mass flow controller (flow
and so forth. For this reason, laboratory test results should be
control method) or a back pressure regulator (pressure control
applied to field situations with caution by qualified personnel.
method), or both. The flow control shall be capable of
NOTE 5—This test method is dependent on the competence of the 3
regulating air flow between 0.01 and 1000 cm /min to 65%.
personnel performing it and the suitability of the equipment and facilities
Two test methods of flow control are required to adapt to a
used. Agencies which meet the criterion of Practice D3740 are generally
wide range of specimen permeability:
considered capable of competent and objective testing.
5.1.2.1 Test Method A, Flow Control Mode—This test
5. Apparatus
method is preferred for high-permeability specimens (greater
5.1 Pneumatic Permeameter—The pneumatic permeameter than about 0.1 darcy) that require flows in the range from 2 to
shall be capable of rapidly establishing a constant flow of air 1000cm /minandlowspecimeninletpressures.Themassflow
through the test specimen and measuring the consequent controller is set for the desired flow through the specimen. It
pressure drop across it. A schematic diagram is shown in Fig. shallautomaticallyadjustitsdownstreampressureasneededto
1. maintain constant mass flow rate of air regardless of tempera-
5.1.1 Air Supply—The compressed air supplied to the pneu- ture or pressure.
matic system shall: 5.1.2.2 Test Method B, Pressure Control Mode—This test
5.1.1.1 Be pulsation-free, have sufficient volumetric capac- method is preferred for low-permeability specimens (less than
ity at all anticipated flow rates, be free of water vapor to a dew about 0.1 darcy) that require control of pressure between 5 and
point of −70°C (−94°F) or less, and be free of oil, 35 kPa (1 and 5 psi) at low flow rates: The back pressure
FIG. 1 Pneumatic Permeameter
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D6539 − 00 (2006)
regulatorshallactasavariablepressurereliefvalvethatcanbe many state agencies as a hazardous material that can cause
adjusted to produce a fixed inlet pressure. The mass flow central nervous system, kidney and liver damage. Mercury, or
controller is set to produce an airflow slightly in excess of the its vapor, may be hazardous to health and corrosive to
test maximum. materials.Cautionshouldbetakenwhenhandlingmercuryand
mercury containing products. See the applicable product Ma-
NOTE 7—The back pressure regulator diverts to the atmosphere a
terial Safety Data Sheet (MSDS) for details and EPA’s
portion of the flow to maintain a constant inlet pressure to produce the
website—http://www.epa.gov/mercury/faq.htm—for addi-
required specimen flow rate.
tionalinformation.Usersshouldbeawarethatsellingmercury,
5.2 Flow Measurement:
mercury containing products, or both, into your state may be
5.2.1 The rate of air flowing into the specimen, Q, shall be
prohibited by state law.
measured to a precision better than 3%. The preferred device
5.3.2 Specimen Inlet Gage Pressure —The specimen inlet
is a digital electronic mass flowmeter upstream from the
pressure, P, shall be mea
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