1、Designation: D5298 10D5298 16Standard Test Method forMeasurement of Soil Potential (Suction) Using Filter Paper1This standard is issued under the fixed designation D5298; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of
2、last revision. 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 laboratory filter papers as passive sensors to evaluate the soil matric (matrix) and total pot
3、ential(suction), a measure of the free energy of the pore-water or tension stress exerted on the pore-water by the soil matrix (1, 2).2 Theterm potential or suction is descriptive of the energy status of soil water.1.2 This test method controls the variables for measurement of the water content of f
4、ilter paper that is in direct contact with soilor in equilibrium with the partial pressure of water vapor in the air of an airtight container enclosing a soil specimen. The filterpaper is enclosed with a soil specimen in the airtight container until moisture equilibrium is established; that is, the
5、partial pressureof water vapor in the air is in equilibrium with the vapor pressure of pore-water in the soil specimen.1.3 This test method provides a procedure for calibrating different types of filter paper for use in evaluating soil matric and totalpotential.1.4 UnitsThe values stated in SI units
6、 are to be regarded as standard. The inch-pound units given in parentheses areapproximate.mathematical conversions, which are provided for information purposes only and are not considered standard.1.5 This standard does not purport to address all of the safety concerns, if any, associated with its u
7、se. It is the responsibilityof the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatorylimitations prior to use.2. Referenced Documents2.1 ASTM Standards:3C114 Test Methods for Chemical Analysis of Hydraulic CementD653 Terminology R
8、elating to Soil, Rock, and Contained FluidsD1125 Test Methods for Electrical Conductivity and Resistivity of WaterD2216 Test Methods for Laboratory Determination of Water (Moisture) Content of Soil and Rock by MassD3740 Practice for Minimum Requirements for Agencies Engaged in Testing and/or Inspect
9、ion of Soil and Rock as Used inEngineering Design and ConstructionD4542 Test Methods for Pore Water Extraction and Determination of the Soluble Salt Content of Soils by RefractometerD4753 Guide for Evaluating, Selecting, and Specifying Balances and Standard Masses for Use in Soil, Rock, and Construc
10、tionMaterials TestingD6836 Test Methods for Determination of the Soil Water Characteristic Curve for Desorption Using Hanging Column, PressureExtractor, Chilled Mirror Hygrometer, or CentrifugeE1E230/E230M Specification for ASTM Liquid-in-Glass Thermometersand Temperature-Electromotive Force (emf) T
11、ables forStandardized ThermocouplesE337 Test Method for Measuring Humidity with a Psychrometer (the Measurement of Wet- and Dry-Bulb Temperatures)E832 Specification for Laboratory Filter PapersE1137/E1137M Specification for Industrial Platinum Resistance ThermometersE2251 Specification for Liquid-in
12、-Glass ASTM Thermometers with Low-Hazard Precision LiquidsE2877 Guide for Digital Contact Thermometers1 This test method is under the jurisdiction of ASTM Committee D18 on Soil and Rock and is the direct responsibility of Subcommittee D18.04 on Hydrologic Propertiesand Hydraulic Barriers.Current edi
13、tion approved July 1, 2010Nov. 15, 2016. Published August 2010December 2016. Originally approved in 1992. Discontinued December 2002 and reinstatedas D529803. Last previous edition approved in 20032010 as D529803.10. DOI: 10.1520/D5298-10.10.1520/D5298-16.2 The boldface numbers in parentheses refer
14、to a list of references at the end of this standard.3 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This docu
15、ment 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. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as
16、appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States13. Terminology3.1 Definitions:3.1.1 For common definition
17、s of technical terms in this standard, refer to Terminology D653.3.2 Definitions of Terms Specific to This Standard:3.2.1 atmospherea unit of pressure equal to 76 cm Mercury or 101 kPa at 0 C.0C.3.2.2 matric (matrix) suction,suction (potential), hm (kPa)the negative pressure (expressed as a positive
18、 value), relative toambient atmospheric pressure on the soil water, to which a solution identical in composition with the soil water must be subjectedin order to be in equilibrium through a porous permeable wall with the soil water; pressure equivalent to that measured by TestMethods in geohydrology
19、/hydrogeology, matric D6836. Matric suction is a function of the relative humidity due to the differencein air the difference between the pore gas pressure, ug, and water pressure acrossthe pore water pressure, uw the water surface; therelative humidity or, in soil; that is, y = ug water vapor uw pr
20、essure decreases as the radius of curvature of the, which yields apositive value in either pressure FL2 water surface decreases. The term “matric” is grammatically correct, while matrix iscommonly used in the civil engineering literature.or pressure head, L.3.2.2.1 DiscussionIn most cases the pore g
21、as is air at atmospheric pressure. Matric suction is also referred to as capillary suction, capillary pressure,and capillary potential. Water flows from a soil with low matric suction (a moist soil) to soil with a high suction (a dry soil). Theterm matrix should not replace matric because only matri
22、c refers to the two solid-liquid binding mechanism (adsorption andcapillarity) contributing to the negative pore-water pressure, uw.3.2.3 molality, moles/1000 gnumber of moles of solute per 1000 g of solvent.3.2.4 molemolecular weight of a substance in grams.3.2.5 osmotic (solute) suction, hs (kPa)t
23、he negative pressure to which a pool of pure water must be subjected in order to bein equilibrium through a semipermeable membrane with a pool containing a solution identical in composition with the soil water;decrease in relative humidity due to the presence of dissolved salts in pore-water.3.2.6 p
24、Fa unit of negative pressure expressed as the logarithm to the base ten of the height in centimeters that a column ofwater will rise by capillary action or negative gauge pressure (kPa) divided by the unit weight of water (kN/m3) times 1000. pF 3 + logarithm to the base ten of the negative pressure
25、in atmospheres. Refer to capillary head or capillary rise in TerminologyD653.3.2.7 soil relative humidity, Rhthe ratio of the vapor pressure of pore water in the soil to the vapor pressure of free pure water.Relative humidity in the soil is defined as relative humidity measured by Test Method E337.3
26、.2.8 total potential (kPa)the sum of gravitational, pressure, osmotic and external gas potentials. Potential may be identifiedwith suction when gravitational and external gas potentials are neglected.3.2.9 total soil suction, h (kPa)the negative pressure, relative to the external gas pressure on the
27、 soil water, to which a poolof pure water must be subjected to be in equilibrium with the soil water through a semipermeable membrane that is permeable towater molecules only. Total soil suction (expressed as a positive value) is the sum of osmotic (solute) and matric (matrix) suctions.3.2.10 vapor
28、pressure of free pure water (kPa)the saturation vapor pressure of free pure water at a given dry-bulb temperature.3.2.11 vapor pressure of pore water in soil (kPa)the partial pressure of water vapor that is in equilibrium with pore-water insoil at a given dry-bulb temperature.4. Summary of Test Meth
29、od4.1 Filter papers are placed in an airtight container with a specimen for seven days to allow sufficient time for the vapor pressureof pore-water in the specimen, vapor pressure of pore water in the filter paper, and partial vapor pressure of water in the air insidethe container to reach equilibri
30、um. The mass of the filter papers is subsequently determined and the suction of the specimen isdetermined from a calibration relationship of the filter paper water content with suction applicable to the type of filter paper andthe test procedure of this test method.5. Significance and Use5.1 Soil su
31、ction is a measure of the free energy of the pore-water in a soil. Soil suction in practical terms is a measure of theaffinity of soil to retain water and can provide information on soil parameters that are influenced by the soil water; for example,volume change, deformation, and strength characteri
32、stics of the soil.5.2 Soil suction is related with soil water content through water retention characteristic curves (see Test Methods D6836). Soilwater content may be found fromdetermined using Test Method D2216.D5298 1625.3 Measurements of soil suction may be used with other soil and environmental
33、parameters to evaluate hydrologic processes(1) and to evaluate the potential for heave or shrinkage, shear strength, modulus, in situ stress and hydraulic conductivity ofunsaturated soils.5.4 The filter paper method of evaluating suction is simple and economical straightforward with a range from 10
34、to100 000100,000 kPa (0.1 to 1000 bars).NOTE 1The quality of the result produced by this standard is dependent on the competence of the personnel performing it, and the suitability of theequipment and facilities used. Agencies that meet the criteria of Practice D3740 are generally considered capable
35、 of competent and objectivetesting/sampling/inspection/etc. Users of this standard are cautioned that compliance with Practice D3740 does not in itself assureensure reliable results.Reliable results depend on many factors; Practice D3740 provides a means of evaluating some of those factors.6. Appara
36、tus6.1 Filter PaperThe paper used must be ash-free quantitative Type II filter paper, see Specification E832; for example,Whatman No. 42, Fisherbrand 9-790A,4 Schleicher and Schuell No. 589 White Ribbon.4 A suitable diameter is 5.5 cm (2.2 in.).NOTE 2Filter papers may be treated by dipping each pape
37、r in a 2 % concentration of formaldehyde prior to use to prevent organism growth on orbiological decomposition of the filter paper. Biological decomposition may be significant when filter papers are subject to a moist, warm environmentfor more than 14 days. Appropriate precautions should be taken wh
38、en preparing formaldehyde solutions and treating filter paper.6.2 Specimen Container120 to 240 mL (4 to 8 oz)fluid-oz) capacity metal or glass (rust free) container and lid (for example,coated with zinc chromate to retard rusting) to contain the specimen and filter papers. The inside of these contai
39、ners may also becoated with wax to retard rusting.6.3 Filter Paper ContainerThis container holds filter paper following the equilibration of suction and removal from thespecimen container.6.3.1 Metal Container AlternateTwo nominal 70 mL (2 oz)fluid-oz) capacity metal moisture containers (aluminum or
40、stainless) with lids to dry the filter paper. The containers should be numbered by imprinting with a metal stamp. The containersshould not be written on with any type of marker or labelledlabeled in any manner. Throw-away vinyl surgical non-powdered orsimilar gloves should be used anytime the small
41、containers designated for filter paper measurements are handled to prevent bodyoils from influencing any mass measurements made prior to handling.6.3.2 Plastic Bag AlternatePlastic bag large enough to accommodate the filter paper disks (approximately 50 mm indimension) capable of an airtight seal.6.
42、4 Insulated ChestA box of approximately 0.03 m3 (1 ft3) capacity insulated with foamed polystyrene or other materialcapable of maintaining temperature within 6 1 C 61C when external temperatures vary 6 3 C.63C.6.5 BalanceA balance or scale having a minimum capacity of 20 g and meeting the requiremen
43、ts of 4.2.1.1 of SpecificationC114 for a balance of 0.0001 g readability. In addition, balances for performance of Test Method D2216, meeting requirementsof Specification D4753.6.6 Drying OvenThermostatically-controlled, preferably of the forced-draft type, and capable of maintaining a uniformtemper
44、ature of 110 6 5 C 5C throughout the drying chamber and meeting requirements of Test Method D2216.6.7 Metal BlockAmetal block 500 500 g mass with a flat surface to hasten cooling of the metal containers with filter paper.6.8 ThermometerAn instrument to determine the temperature of the tested soil to
45、 an accuracy of 6 1 C 61C in accordancewith E1E230/E230M, E1137/E1137M, E2251or , or E2251E2877.6.9 Miscellaneous EquipmentMiscellaneous EquipmentTweezers, Tweezers, trimming knife, flexible plastic electrical tape,O-rings, screen wire, brass discs, etc. Tweezers should be at least 110 mm (4.5 in.)
46、in length.6.10 DesiccatorA desiccator jar of suitable size containing silica gel or anhydrous calcium sulfate.NOTE 3Anhydrous calcium sulfate is sold under the trade name Drierite.NOTE 4It is preferable to use a desiccant that changes color to indicate when it needs reconstitution.7. Calibration7.1
47、Obtain a calibration curve applicable to a specific filter paper by following the procedure in Section 8, except for replacingthe soil specimen with salt solutions such as reagent grade potassium chloride or sodium chloride of known molality in distilledwater.7.1.1 Suspend the filter paper above at
48、least 50 ccmL of a salt solution in the specimen container, see 6.2, by placing it on animprovised platform made of inert material such as plastic tubing or stainless steel screen.7.1.2 Calculate the suction of the filter paper from the relative humidity of the air above the solution by:4 The sole s
49、ource of supply of the apparatus known to the committee at this time is Thomas Scientific Supply, P.O. Box 99, Swedesboro, NJ 08085. If you are aware ofalternative suppliers, please provide this information to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of the responsibletechnical committee,1 which you may attend.D5298 163h5RTv lnRh (1)where:h = suction, kPa,R = ideal gas constant, 8.31432 Joules/moleK,T = absolute temperature, degrees kelvin (K),v = volume of 1000 moles of liquid wa
