ASTM D4491-99a(2014)e1
(Test Method)Standard Test Methods for Water Permeability of Geotextiles by Permittivity
Standard Test Methods for Water Permeability of Geotextiles by Permittivity
SIGNIFICANCE AND USE
5.1 These test methods are considered satisfactory for acceptance testing of commercial shipments of geotextiles since the methods have been used extensively in the trade for acceptance testing.
5.1.1 In case of a dispute arising from differences in reported test results when using these test methods for acceptance testing of commercial shipments, the purchaser and the supplier should conduct comparative tests to determine if there is a statistical bias between their laboratories. Competent statistical assistance is recommended for the investigation of bias. As a minimum, the two parties should take a group of test specimens that are as homogeneous as possible and that are from a lot of material of the type in question. The test specimens should then be randomly assigned in numbers to each laboratory for testing. The average results from the two laboratories should be compared using Student's t-test for unpaired data and an acceptable probability level chosen by the two parties before the start of testing. If a bias is found, either its cause must be found and corrected, or the purchaser and the supplier must agree to interpret future test results in light of the known bias.
5.1.2 Permittivity is an indicator of the quantity of water that can pass through a geotextile in an isolated condition.
5.1.3 As there are many applications and environmental conditions under which a geotextile may be used, care should be taken when attempting to apply the results of these test methods to the field performance of a geotextile.
5.2 Since there are geotextiles of various thicknesses in use, evaluation in terms of their Darcy coefficient of permeabilities can be misleading. In many instances, it is more significant to evaluate the quantity of water that would pass through a geotextile under a given head over a particular cross-sectional area; this is expressed as permittivity.
5.3 If the permeability of an individual geotextile is of importance, a nominal coefficien...
SCOPE
1.1 These test methods cover procedures for determining the hydraulic conductivity (water permeability) of geotextiles in terms of permittivity under standard testing conditions, in the uncompressed state. Included are two procedures: the constant head method and the falling head method.
1.2 The values stated in SI units are to be regarded as the standard. The inch-pound units stated in parentheses are provided for information only.
1.3 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)
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation: D4491 − 99a(Reapproved 2014)
Standard Test Methods for
Water Permeability of Geotextiles by Permittivity
This standard is issued under the fixed designation D4491; 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.
This standard has been approved for use by agencies of the U.S. Department of Defense.
ε NOTE—Editorial changes were made throughout in February 2014.
1. Scope 3. Terminology
1.1 These test methods cover procedures for determining 3.1 Definitions:
the hydraulic conductivity (water permeability) of geotextiles 3.1.1 geotechnics, n—the application of scientific methods
in terms of permittivity under standard testing conditions, in and engineering principles to the acquisition, interpretation,
the uncompressed state. Included are two procedures: the and use of knowledge of materials of the earth’s crust to the
constant head method and the falling head method. solution of engineering problems.
3.1.1.1 Discussion—Geotechnics embraces the fields of soil
1.2 The values stated in SI units are to be regarded as the
mechanics, rock mechanics, and many of the engineering
standard. The inch-pound units stated in parentheses are
aspects of geology, geophysics, hydrology, and related sci-
provided for information only.
ences.
1.3 This standard does not purport to address all of the
3.1.2 geotextile, n—a permeable geosynthetic comprised
safety concerns, if any, associated with its use. It is the
solely of textiles.
responsibility of the user of this standard to establish appro-
3.1.3 permeability, n—the rate of flow of a liquid under a
priate safety and health practices and determine the applica-
bility of regulatory limitations prior to use. differential pressure through a material.
3.1.3.1 Discussion—The nominal thickness is used as it is
2. Referenced Documents difficult to evaluate the pressure on the geotextile during the
2 test, thereby making it difficult to determine the thickness of
2.1 ASTM Standards:
the fabric under these test conditions.
D123Terminology Relating to Textiles
3.1.4 permeability, n—of geotextiles, hydraulic conductiv-
D653Terminology Relating to Soil, Rock, and Contained
Fluids ity.
D4439Terminology for Geosynthetics
3.1.5 permittivity, (ψ), (T−1), n—of geotextiles, the volu-
D5199Test Method for Measuring the Nominal Thickness
metric flow rate of water per unit cross sectional area per unit
of Geosynthetics
head under laminar flow conditions, in the normal direction
E691Practice for Conducting an Interlaboratory Study to
through a geotextile.
Determine the Precision of a Test Method
3.1.6 For the definitions of other terms relating to
2.2 ASTM Adjuncts:
geotextiles, refer toTerminology D4439. For the definitions of
Detailed Drawings and Materials List for Construction, 10
textile terms, refer to Terminology D123. For the definition of
Drawings
coefficient of permeability, refer to Terminology D653.
4. Summary of Test Methods
These test methods are under the jurisdiction of ASTM Committee D35 on
4.1 These test methods describe procedures for determining
Geosynthetics and are the direct responsibility of Subcommittee D35.03 on
Permeability and Filtration.
the permittivity of geotextiles using constant head or falling
Current edition approved Jan. 1, 2014. Published February 2014. Originally
head test procedures, as follows:
approved in 1985. Last previous edition approved in 2009 as D4491–99a(2009).
4.1.1 ConstantHeadTest—Aheadof50mm(2in.)ofwater
DOI: 10.1520/D4491-99AR14E01.
is maintained on the geotextile throughout the test. The
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
quantity of flow is measured versus time. The constant head
Standards volume information, refer to the standard’s Document Summary page on
test is used when the flow rate of water through the geotextile
the ASTM website.
is so large that it is difficult to obtain readings of head change
Detailed drawings and a materials list for construction are available from
ASTM International Headquarters. Order Adjunct No. ADJD4491. versus time in the falling head test.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
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D4491 − 99a (2014)
NOTE 1—Data has shown agreement between the falling and constant
6. Apparatus
head methods of determining permittivity of geotextiles. Selection of the
6.1 The apparatus shall conform to one of the following
test method, that is, constant or falling head, is left to the technician
arrangements:
performing the test.
6.1.1 The apparatus must be capable of maintaining a
4.1.2 Falling Head Test—A column of water is allowed to
constant head of water on the geotextile being tested, or
flow through the geotextile and readings of head changes
6.1.2 Theapparatusmustbecapableofbeingusedasfalling
versus time are taken. The flow rate of water through the
head apparatus.
geotextile must be slow enough to obtain accurate readings.
6.2 In addition, the apparatus must not be the controlling
agent for flow during the test. It will be necessary to establish
5. Significance and Use
a calibration curve of volumetric flow rate versus head for the
5.1 These test methods are considered satisfactory for ac-
apparatus alone in order to establish compliance with this
ceptance testing of commercial shipments of geotextiles since
requirement (see 11.7).
the methods have been used extensively in the trade for
6.3 Refer to Fig. 1 for a schematic drawing of a device that
acceptance testing.
conforms to all of the above requirements.The device consists
5.1.1 In case of a dispute arising from differences in
of an upper and lower unit, which fasten together. The
reported test results when using these test methods for accep-
geotextile specimen is positioned in the bottom of the upper
tance testing of commercial shipments, the purchaser and the
unit. There is a standpipe for measuring the constant head
suppliershouldconductcomparativeteststodetermineifthere
value. The rotating discharge pipe allows adjustment of the
is a statistical bias between their laboratories. Competent
head of water at the bottom of the specimen. See ADJD4491.
statistical assistance is recommended for the investigation of
bias.Asaminimum,thetwopartiesshouldtakeagroupoftest NOTE 3—The location of the manometer for measuring the headloss in
either the constant head or falling head method shall be located directly
specimens that are as homogeneous as possible and that are
beneath the specimen. For the device shown in Fig. 1, this may be
from a lot of material of the type in question. The test
accomplished by drilling a small (3mm; ⁄8 in) diameter hole in the top
specimens should then be randomly assigned in numbers to
plate of the bottom reservoir tank directly beneath the specimen, and
each laboratory for testing. The average results from the two
attaching the manometer to this plate.
laboratories should be compared using Student’s t-test for
7. Sampling
unpaireddataandanacceptableprobabilitylevelchosenbythe
two parties before the start of testing. If a bias is found, either
7.1 LotSample—Asalotsampleforacceptancetesting,take
itscausemustbefoundandcorrected,orthepurchaserandthe
at random the number of rolls of geotextile directed in an
suppliermustagreetointerpretfuturetestresultsinlightofthe
applicable material specification or other agreement between
known bias.
the purchaser and the supplier. Consider rolls of geotextile to
5.1.2 Permittivity is an indicator of the quantity of water
be the primary sampling units. If the specification requires
that can pass through a geotextile in an isolated condition.
samplingduringmanufacture,selecttherollsforthelotsample
at uniformly spaced time intervals throughout the production
5.1.3 As there are many applications and environmental
conditions under which a geotextile may be used, care should period.
be taken when attempting to apply the results of these test
NOTE 4—An adequate specification or other agreement between the
methods to the field performance of a geotextile.
purchaser and the supplier requires taking into account the variability
between rolls of geotextile and between specimens from a swatch from a
5.2 Sincetherearegeotextilesofvariousthicknessesinuse,
roll of geotextile so as to provide a sampling plan with a meaningful
evaluation in terms of their Darcy coefficient of permeabilities
producer’s risk, consumer’s risk, acceptable quality level, and limiting
can be misleading. In many instances, it is more significant to
quality level.
evaluate the quantity of water that would pass through a
7.2 Laboratory Sample—Take for the laboratory sample a
geotextile under a given head over a particular cross-sectional
full roll width sample extending a minimum of 1 m along the
area; this is expressed as permittivity.
selvage from each sample roll such that the requirements of
Section 9 can be met.Take a sample that will exclude material
5.3 If the permeability of an individual geotextile is of
from the outer wrap of the roll or the inner wrap around the
importance, a nominal coefficient of permeability, as related to
core unless the sample is taken at the production site, at which
geotechnical engineering, may be computed. By multiplying
point inner and outer wrap material may be used.
permittivity times the nominal thickness of the geotextile, as
determined by Test Method D5199, the nominal coefficient of
8. Test Water Preparation
permeability is obtained.
8.1 To provide reproducible test results, the test water shall
NOTE 2—The nominal thickness is used as it is difficult to evaluate the
be de-aired under a vacuum of 710 mm (28 in.) of mercury
pressure on the geotextile during the test, thereby making it difficult to
(Hg)foraperiodoftimetobringthedissolvedoxygencontent
determine the thickness of the fabric under these test conditions.
down to a maximum of six parts per million. The dissolved
oxygen content may be determined by either commercially
available chemical kits or by a dissolved oxygen meter.
Supporting data have been filed atASTM International Headquarters and may
beobtainedbyrequestingResearchReportRR:D35-1007.ContactASTMCustomer NOTE 5—The de-airing system may be either a commercially available
Service at service@astm.org. system or one consisting of a vacuum pump capable of removing a
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D4491 − 99a (2014)
FIG. 1 Constant and Falling Head Permeability Apparatus
minimumof150L/minofairinconnectionwithanon-collapsiblestorage
9. Specimen Preparation
tankwithalargeenoughstoragecapacityforthetestseries,oratleastone
specimen at a time. 9.1 To obtain a representative value of permittivity, take
four specimens from each full width laboratory sample as
8.2 Allow the de-aired water to stand in a closed storage
described below.
tank under a slight vacuum until room temperature is attained.
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D4491 − 99a (2014)
9.2 Referring to Fig. 2, select four specimens,A, B, C, and 11.2 Open the bleed valve and backfill the system through
D, as follows: the standpipe or discharge pipe, with de-aired water. Backfill-
9.2.1 Selectfourspecimensequallyspacedalongadiagonal ing in this manner forces any trapped air out of the system and
line extending from the lower left hand corner to the upper the geotextile.
righthandcornerofthelaboratorysample.NeitherspecimenA
NOTE7—Thewatershouldbeatthebottomlevelofthespecimenatthe
or D shall be closer to the corner of the laboratory sample than
time of specimen installation.
200 mm (8 in.).
11.3 Close the bleed valve once water flows from it.
9.2.2 Take specimenAat the center of the sample, B at one
Continue to fill the apparatus with de-aired water until the
corner (center located 200 mm (8 in.) from the corner), C
water level reaches the overflow.
midway betweenAand B, and D the same distance fromAas
C, located on a line with A, B, and C.
11.4 With water flowing into the system through the water
9.2.3 Cut specimens shall fit the testing apparatus, for
inlet, adjust the discharge pipe along with the rate of water
example,73mm(2.87in.)indiameterforthedeviceillustrated
flowing into the apparatus to obtain a 50-mm (2-in.) head of
in Fig. 1.
water on the geotextile. This is the head (h) under which the
test will be performed initially.
9.3 Conditionthespecimenbysoakinginaclosedcontainer
of de-aired water, at room conditions, for a period of 2 h. The
11.5 Submergeatubeattachedtoasourceofvacuumtojust
minimum specimen diameter is to be 50 mm (2 in.).
above (10 mm (0.5 in.)) the surface of the geotextile, moving
thetubegentlyoverthesurfacewhileapplyingaslightvacuum
NOTE 6—If the illustrated device is used, the specimens are attached to
the specimen ring by contact cement. in order to remove any trapped air that may be in or on the
specimen.Ifnecessary,readjusttheheadto50mm(2in.)after
10. Operator Process Control
removing the vacuum.
10.1 Prepare four specimens of Standard U.S. Mesh Sieve
11.6 Record the values of time (t ), quantity of flow (Q)as
to fit the test apparatus.
collected from the discharge pipe, and water temperature (T),
holding the head at 50 mm (2 in.). Make at least five readings
10.2 Following Section 11 or Section 13, depending on the
per specimen and determine an average value of permittivity
methodtobeusedforthegeotextilespecimens,performtesting
for the specimen.
on each mesh specimen.
10.3 Based on an interlaboratory test, involving seven
NOTE 8—The quantity of flow may be measured in millilitres and then
converted to cubic millimetres for the computation of permittivity (1
laboratories, the permittivity of No 200 Standard US Mesh
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mL=1000 mm ).
Sieve material has been determined to be 5.00 s , with a
standard deviation of 0.65.
11.7 Afterthefirstspecimenhasbeentestedundera50-mm
10.3.1 New operator process control shall be performed
(2-in.) head, using the same specimen, start with a 10-mm
until it is demonstrated that the operator is proficient in test
( ⁄8-in.) head and repeat the procedure. Increase the head by 5
performance as demonstrated by obtaining the value of per-
mm ( ⁄16 in.) after every five readings. Increase the head until
mittivity stated in 10.3, plus or minus two standard deviations.
a75-mm(3-in.)headisreached.Usethisdatatodeterminethe
10.3.2 Following initial proficiency testing, the operator
region of laminar flow. Plot volumetric flow rate, v, (where
shall perform process control testing on a semi-annual basi
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