1、Designation: D5493 06 (Reapproved 2011)Standard Test Method forPermittivity of Geotextiles Under Load1This standard is issued under the fixed designation D5493; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revis
2、ion. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers the determination of the waterpermittivity behavior of geotextiles in a direction normal to theplane of
3、the geotextile when subjected to specific normalcompressive loads.1.2 Use of this test method is limited to geotextiles. This testmethod is not intended for application with geotextile-relatedproducts such as geogrids, geonets, geomembranes, and othergeocomposites.1.3 The values stated in SI units a
4、re to be regarded as thestandard. The inch-pound units given in parentheses are forinformation only.1.4 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 heal
5、th practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D123 Terminology Relating to TextilesD653 Terminology Relating to Soil, Rock, and ContainedFluidsD4354 Practice for Sampling of Geosynthetics for TestingD4439 Terminology f
6、or GeosyntheticsD4491 Test Methods for Water Permeability of Geotextilesby PermittivityD4716 Test Method for Determining the (In-plane) FlowRate per Unit Width and Hydraulic Transmissivity of aGeosynthetic Using a Constant HeadE11 Specification for Woven Wire Test Sieve Cloth and TestSieves3. Termin
7、ology3.1 Definitions:3.1.1 geotextile, nany permeable textile material usedwith foundation, soil, rock, earth, or any other geotechnicalengineering related material as an integral part of a manmadeproject, structure, or system (see Terminology D4439).3.1.2 hydraulic gradient, i, nthe loss of hydraul
8、ic headper unit distance of flow, dh/dL (see Test Method D4716).3.1.3 permittivity, (c), (T-1), nof geotextiles, the volumet-ric flow rate of water per unit cross-sectional area per unit headunder laminar flow conditions, in the normal direction througha geotextile (see Terminology D4439).3.2 For th
9、e definitions of other terms relating to geotextiles,refer to Terminology D4439. For the definitions of textileterms, refer to Terminology D123. For the definitions ofcoefficient of permeability, refer to Terminology D653.4. Summary of Test Method4.1 This test method provides a procedure for measuri
10、ng thewater flow, in the normal direction through a known crosssection of a single layer of a geotextile at predeterminedconstant hydraulic heads over a range of applied normalcompressive stresses.4.2 The permittivity of a geotextile, c, can be determined bymeasuring the flow rate of water, in the n
11、ormal direction,through a known cross section of a geotextile at predeterminedconstant water heads.4.3 Water flow through geotextiles can be laminar, transient,or turbulent, and therefore permittivity cannot be taken as aconstant.5. Significance and Use5.1 The thickness of a geotextile decreases wit
12、h increase inthe normal compressive stress. This decrease in thickness mayresult in the partial closing or the opening of the voids ofgeotextile depending on its initial structure and the boundaryconditions.1This test method is under the jurisdiction of ASTM Committee D35 onGeosynthetics and is the
13、direct responsibility of Subcommittee D35.03 on Perme-ability and Filtration.Current edition approved June 1, 2011. Published July 2011. Originally approvedin 1993. Last previous edition approved in 2006 as D5493 06. DOI: 10.1520/D5493-06R11.2For referenced ASTM standards, visit the ASTM website, ww
14、w.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.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.5.2
15、This test method measures the permittivity due to achange of void structure of a geotextile as a result of an appliedcompressive stress.6. Apparatus6.1 The apparatus is a constant head permeameter. Generalguidance on the hydraulic design of a constant head permeame-ter can be found in Test Method D4
16、491.6.2 The components installed around the test specimen aredesigned in such a way that a normal load can be applieduniformly on the entire flow surface without restraining sig-nificantly the flow rate. The permittivity of the apparatus,calculated using the calibration curve established in section
17、10,shall be at least 10 times greater than the permittivity of the testspecimen under the hydraulic conditions prevailing during agiven test. However, the central deflection of the loadingmechanism on the plane of the geotextile shall not exceed0.025 mm while subjected to the maximum normal loadappl
18、ied during the test.6.3 The recommended apparatus configuration is shown inFig. 1:6.3.1 An optimum flow diameter has been found to be 50mm to minimize hydraulic side effects while ensuring anoptimum rigidity of the loading mechanism.6.3.2 A wire meshes, 1.0 mm in opening, complying withSpecification
19、 E11 is installed as the contact surface on bothsides of the test specimen.6.3.3 Two rigid metallic plate with the geometry shown onFigure 2 act as a structural component on both sides of the wiremeshes. The lower one is supported by the apparatus, while theupper one can move freely but is adjusted
20、to the diameter of theflow channel.6.3.4 The upper metallic plate is connected to a devicecapable of applying the requested normal load on the testspecimen (dead loads, air piston or any suitable device). Themechanical connection between the upper metallic plate andthe loading mechanism consists of
21、four rods, 3 mm in diameter,distributed on a circle approximately 30 mm in diameter.6.3.5 A dial indicator can be connected to the loadingmechanism to monitor the specimen thickness during the test.7. Sampling7.1 Lot SampleAs a lot sample for acceptance testing,take at random the number of rolls of
22、geotextile directed in anapplicable material specification and the supplier (for examplePractice D4354) or other agreement between the purchaser andthe supplier. Consider rolls of geotextile to be the primarysampling units. If the specification requires sampling duringmanufacture, select the rolls f
23、or the lot sample at uniformlyspaced time intervals throughout the production period.NOTE 1An adequate specification or other agreement between thepurchaser and the supplier requires taking into account the variabilitybetween rolls of geotextile and between specimens from a swatch from aroll of geot
24、extile so as to provide a sampling plan with a meaningfulproducers risk, consumers risk, acceptable quality level, and limitingquality level.7.2 Laboratory SampleConsider the units in the lotsample as the units in the laboratory sample. Take a sample thatwill exclude material from the outer wrap of
25、the roll or theinner wrap around the core unless the sample is taken at theproduction site, at which point the inner and outer wrapmaterial may be used.8. Test Water Preparation8.1 De-air the test water to provide reproducible test results.8.2 De-air the water used for saturation.FIG. 1 Specimen Hol
26、der and Loading MechanismD5493 06 (2011)28.3 De-air the water under a vacuum of 710 mm (28 in.) ofmercury (Hg) for the period of time to bring the dissolvedoxygen content down to a maximum of 6 ppm.8.4 Use dissolved oxygen meter or commercially availablechemical kits to determine the dissolved oxyge
27、n content.8.5 The deaired system may be a commercially availablesystem, or one consisting of a vacuum pump capable ofremoving a minimum of 150 L/min of air in connection with anon-collapsible storage tank with a large enough storagecapacity for the test series, or at least one specimen at a time.All
28、ow the deaired water to stand in closed storage under aslight vacuum until room temperature is attained.8.6 If water temperature other than 20C is being used,make a temperature correction to the resulting value ofpermittivity.8.7 Determine the temperature correction factor using thefollowing equatio
29、n:Rt 5 ut / u20 (1)where:ut = water viscosity at test temperature, mP, as deter-mined from Table 1, andu20 = water viscosity at 20C, mP.9. Specimen Preparation9.1 Prepare four specimens of the geotextile to be testedavoiding sampling along the edges of the geotextile roll toensure homogeneity of the
30、 specimens.9.2 The minimum specimen diameter is 50 mm.9.3 Referring to Fig. 2, select the specimens, A, B, C, and Das follows:9.3.1 Take Specimen A at the center of the sample, B at onecorner (center located 200 mm from the corner), C midwaybetweenAand B, and D the same distance fromAas C, locatedon
31、 a line with A, B, and C.9.3.2 Cut specimens shall fit the testing apparatus.10. Calibrations10.1 Hydraulic Calibration:10.1.1 Run at least 3 tests without any geotextile specimeninstalled in the apparatus, each of them being ran with thesystem set to apply different normal loads spread over theequi
32、pment capability (that is, 2, 20, and 200 kPa). Thespecimen shall be replaced by a rigid material approximately25 to 30 mm in diameter that will not restrain the flow (such asa 1 to 2 mm long section of a thick 25 mm PVC plastic pipe).For each test, measure the water heads corresponding to at least1
33、0 different flow rates uniformly spread between 0 and theequipment capability.10.1.2 Draw the Water Head versus Flow Rate curve andcalculate the intrinsic permittivity of the apparatus for eachflow rate using Eq 2. Plot both curves on the same graph asshown on Fig. 2.10.2 Normal Load CalibrationUse
34、a convenient systemto control the precision of the normal load applied on thegeotextile. The normal load effectively applied shall be within5 % of the targeted load.10.3 Thickness Measurement CalibrationAlthough thick-ness measurement is not a mandatory requirement, if thethickness of the material i
35、s monitored, it shall be calibratedfirst. In that case, the central deflection requirement expressedin 6.2 shall be verified using the procedure presented below.10.3.1 Install a metallic ring 50 mm in diameter (or the innerdiameter of the flow channel), witha1mmwall and 10 mmthick in the sample hold
36、er in place of the geotextile.10.3.2 Apply the minimum load that can be achieved withthe equipment (that is, 2 kPa) and record the value provided bythe dial indicator as the zero for calibration purposes.10.3.3 Apply by increments 10 different normal loads uni-formly spread over the apparatus capabi
37、lity and record thecorresponding values given by the dial indicator.10.3.4 Plot the thickness versus load curve and verify thatthe deflection measured under 2, 20, and 200 kPa normal loadare less than 0.025 mm.TABLE 1 Viscosity of Water Versus TemperatureTemperature, C Viscosity (Poiseuille)A0 1.792
38、1 3 10-61 1.7313 3 10-62 1.6278 3 10-63 1.6191 3 10-64 1.5674 3 10-65 1.5188 3 10-66 1.4728 3 10-67 1.4284 3 10-68 1.3860 3 10-69 1.3462 3 10-610 1.3077 3 10-611 1.2713 3 10-612 1.2363 3 10-613 1.2028 3 10-614 1.1709 3 10-615 1.1404 3 10-616 1.1111 3 10-617 1.0828 3 10-618 1.0559 3 10-619 1.0299 3 1
39、0-620 1.0050 3 10-621 0.9810 3 10-622 0.9579 3 10-623 0.9358 3 10-624 0.9142 3 10-625 0.8937 3 10-6APoiseuille = kg s-1m-1= Nsm.FIG. 2 Hydraulic Calibration CurveD5493 06 (2011)311. Test Procedure11.1 Soak the specimen in a vessel containing deaired water,at room conditions, for a period of at least
40、2htoensuresaturation and wetting.11.2 Maintain the test specimen, underwater at all timesprior to and during the test.11.3 Allow the deaired water to flow from the bottom of theapparatus to the predetermined overflow located on the top ofthe upper section of the water tank using the drain tube as th
41、ewater inlet.11.4 Place the geotextile specimen in the apparatus insequence as shown in Fig. 1.11.5 Lower the piston until it reaches the upper metallicplate.11.6 Apply a load equal to 2 kPa.NOTE 2Unless otherwise specified, the permittivity shall be measuredunder 2, 20, and 200 kPa. If a different
42、normal load is required, the firstapplied normal load shall be the lightest one.11.7 Continue to fill the tank from the outlet until the waterlevel reaches the outlet level. This step is needed to flush outany air bubbles located in the upper plate and the upper sectionof the cylinder. Air bubbles i
43、n the system may lead toerroneous and non-reproducible test results.11.8 Connect the water line to the inlet reservoir to run thetest.11.9 The seating period shall be long enough to reach athickness variation of less than 0.0025 mm per minute.11.10 Measure the flow rate under total (uncorrected) hy-
44、draulic heads of approximately 15, 25, 50, and 75 mm, or morein order to apply an actual (corrected) hydraulic head in therange of 10 to at least 50 mm. Conduct three flow ratemeasurements for each water head and verify that the differ-ence between the lower and the higher value is less than 5 %.11.
45、11 Increase the normal load to reach the next requestednormal load and repeat the flow measurements as described in11.10.11.12 Repeat steps 11.9 to 11.11 for three additional testspecimens.NOTE 3If a reduction of permittivity is observed for a given product,it could be either caused by the products
46、behavior (sensitivity to thenormal load) or by air clogging during the test. The following procedurecan be used to assess whether air clogging has influenced the result or not:(1) apply a single normal load on the specimen; (2) measure itspermittivity; (3) let the water flow through the specimen for
47、 a period oftime equivalent to the total duration of the test, varying the water head insuch a way that the hydraulic head history of the actual test will bereproduced; (4) repeat the permittivity measurement; and (5) compare thedeviation between the two permittivity measurements.12. Calculation12.1
48、 Use the calibration curve built in 10.1 to determine thewater head correction DHQ to be considered for each indi-vidual flow rate measurement.NOTE 4A power regression built with the values measured in 10.1usually provides a very good tool to automate the water head correction.12.2 Calculate the per
49、mittivity for each individual measure-ments using Eq 2.c5Q 3 Rt/ SDH DHQ!# (2)where:Q = measured flow rate (Q = V / t, where V = volumeand t = time),Rt= temperature correction factor,S = flow surface,DH = measured water head, andDHQ= water head correction.12.3 Plot the permittivity versus the corrected water headfor each individual test specimen and determine the permittiv-ity in the laminar region, which is constant up to a certain waterhead.12.4 Determine the permittivity under a 50 mm water headusing a best fit curve and reading the value correspondin
