ASTM D4959-2016 Standard Test Method for Determination of Water Content of Soil By Direct Heating《采用直接加热法测定土壤中含水量的标准试验方法》.pdf

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1、Designation: D4959 16Standard Test Method forDetermination of Water Content of Soil By Direct Heating1This standard is issued under the fixed designation D4959; 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. Scope*1.1 This test method covers procedures for determining thewater content of soils by drying with direct heat, such as usinga hotplat

3、e, stove, blowtorch, and the like.1.2 This test method can be used as a substitute for TestMethods D2216 when more rapid results are desired toexpedite other phases of testing and slightly less accurateresults are acceptable.1.3 When questions of accuracy between this test methodand Test Methods D22

4、16 arise, Test Methods D2216 shall bethe referee method.1.4 This test method is applicable for most soil types. Forsome soils, such as those containing significant amounts ofhalloysite, mica, montmorillonite, gypsum, or other hydratedmaterials, highly organic soils or soils that contain dissolvedsol

5、ids, (such as salt in the case of marine deposits), this testmethod may not yield reliable water content values due to thepotential for heating above 110C or lack of means to accountfor the presence of precipitated solids that were previouslydissolved.1.5 The values stated in SI units are to be rega

6、rded asstandard. Performance of the test method utilizing anothersystem of units shall not be considered non-conformance. Thesieve designations are identified using the “standard” system inaccordance with Specification E11, such as 2.0-mm and19-mm, followed by the “alternative” system of No. 10 and3

7、4-in., respectively, in parentheses.1.6 All observed and calculated values shall conform to theguidelines for significant digits and rounding established inD6026, unless otherwise superseded by this standard.1.6.1 The procedures used to specify how data are collected/recorded or calculated, in this

8、standard are regarded as theindustry standard. In addition, they are representative of thesignificant digits that generally should be retained. The proce-dures used do not consider material variation, purpose forobtaining the data, special purpose studies, or any consider-ations for the users object

9、ives; and it is common practice toincrease or reduce significant digits of reported data to becommensurate with these considerations. It is beyond the scopeof this standard to consider significant digits used in analysismethods for engineering design.1.6.2 Significant digits are especially important

10、 if the watercontent will be used to calculate other relationships such asmoist mass to dry mass or vice versa, wet unit weight to dryunit weight or vice versa, and total density to dry density orvice versa. For example, if four significant digits are requiredin any of the above calculations, then t

11、he water content has tobe recorded to the nearest 0.1 %, for water contents below100 %. This occurs since 1 plus the water content (not inpercent) will have four significant digits regardless of what thevalue of the water content is (below 100 %); that is, 1 plus0.1/100 = 1.001, a value with four si

12、gnificant digits. While, ifthree significant digits are acceptable, then the water contentcan be recorded to the nearest 1 %.1.7 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 app

13、ro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D653 Terminology Relating to Soil, Rock, and ContainedFluidsD2216 Test Methods for Laboratory Determination of Water(Moisture) Content of Soil and

14、Rock by MassD3740 Practice for Minimum Requirements for AgenciesEngaged in Testing and/or Inspection of Soil and Rock asUsed in Engineering Design and ConstructionD4753 Guide for Evaluating, Selecting, and Specifying Bal-ances and Standard Masses for Use in Soil, Rock, andConstruction Materials Test

15、ingD6026 Practice for Using Significant Digits in GeotechnicalData1This test method is under the jurisdiction ofASTM Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.08 on Special andConstruction Control Tests.Current edition approved Jan. 1, 2016. Published January

16、 2016. Originallyapproved in 1989. Last previous edition approved in 2007 as D4959 07. DOI:10.1520/D4959-16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the stan

17、dards Document Summary page onthe ASTM website.*A Summary of Changes section appears at the end of this standardCopyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States1E11 Specification for Woven Wire Test Sieve Cloth and TestSieves3. Termino

18、logy3.1 DefinitionsFor definitions of common technical termsused in this standard, refer to Terminology D653.3.2 Definitions of Terms Specific to This Standard:3.2.1 direct heatinga process by which the soil is dried byconductive heating from the direct application of heat in excessof 110C to the sp

19、ecimen container, such as provided by a hotplate, gas stove or burner, heatlamps, or other heat sources.Direct application of heat by flame to the specimen is notappropriate.4. Summary of Test Method4.1 A moist soil specimen is placed in a suitable containerand its mass is determined. It is then sub

20、jected to drying by theapplication of direct heat until dry by appearance, removedfrom the heat source, and its new mass is determined. Thisprocedure is repeated until the mass becomes nearly constantwithin specified limits.4.2 The difference between the masses of the moist speci-men and the dried s

21、pecimen is used as the mass of watercontained in the specimen. The water content (expressed as apercentage) is determined by dividing the mass of water by thedry mass of soil, multiplied by 100. For a given soil type andspecimen size, the time to achieve a constant dry mass can benoted and used to e

22、stimate drying time for subsequent tests ofthe same soil type using the same size specimen and dryingapparatus.5. Significance and Use5.1 The water content of a soil is used throughout geotech-nical engineering practice both in the laboratory and in thefield. The use of Test Methods D2216 for water

23、contentdetermination can be time consuming and there are occasionswhen a more expedient method is desirable. Drying by directheating is one such method. Results of this test method havebeen demonstrated to be of satisfactory accuracy for use infield control work, such as in the determination of wate

24、rcontent, and in the determination of in-place dry unit weight ofsoils.5.2 The principal objection to the use of the direct heatingfor water content determination is the possibility of overheat-ing the soil, thereby yielding a water content higher than wouldbe determined by Test Methods D2216. While

25、 not eliminatingthis possibility, the incremental drying procedure in this testmethod will minimize its effects. Some heat sources havesettings or controls that can also be used to reduce overheating.Loose fitting covers or enclosures can also be used to reduceoverheating while assisting in uniform

26、heat distribution.5.3 The behavior of a soil when subjected to direct heatingis dependent on its mineralogical composition, and as a result,no one procedure is applicable for all types of soils or heatsources. The general procedure of this test method applies to allsoils, but test details may need t

27、o be tailored to the soil beingtested.5.4 When this test method is to be used repeatedly on thesame or similar soil from a given site, a correction factor canusually be determined by making several comparisons betweenthe results of this test method and Test Methods D2216.Acorrection factor is valid

28、when the difference is consistent forseveral comparisons, and is reconfirmed on a regular specifiedbasis.5.5 This test method may not be appropriate when preciseresults are required, or when minor variations in water contentwill affect the results of other test methods, such as borderlinesituations

29、where small variations in the measured water contentcould affect acceptance or rejection.5.6 This test method is not appropriate for specimens knownto contain flammable organics or contaminants, and other testmethods should be utilized in these situations.NOTE 1The quality of the results produced by

30、 this test method isdependent on the competence of the personnel performing it and thesuitability of the equipment and facilities used. Agencies that meet thecriteria of Practice D3740 are generally considered capable of competentand objective testing/sampling/inspection. Users of this test method a

31、recautioned that compliance with Practice D3740 does not in itself ensurereliable results . Reliable results depend on many factors; Practice D3740provides a means of evaluating some of those factors.6. Interferences6.1 When testing sand and gravel size particles, additionalcare should be taken to a

32、void the possibility of particleshattering.6.2 Due to the localized high temperatures in the soil duringtesting, the physical characteristics of the soil may be altered.Degradation of individual particles may occur, along withvaporization, chemical transition, or loss of organics.Therefore, specimen

33、s used in this test method should not beused for other tests subsequent to drying.7. Apparatus7.1 Direct Heat SourceAny source of heat that can bedirected to the soil specimen to raise the specimen temperatureto or above 110C. Commonly used sources include electric,gas, butane or oil-fired stoves, a

34、nd hotplates, blowtorches, heatlamps, hair driers, space heaters, etc. Heat sources that directlyapply open flame to the specimen may cause extreme degra-dation of the specimen along with oxidation of and depositingof soot in the specimen and should not be used.7.2 BalancesAll balances shall meet th

35、e requirements ofGuide D4753 and this section. A Class GP2 balance of 0.1 greadability is generally required. However, the balance usedmay be controlled by the number of significant digits needed(see 1.6).7.3 Specimen ContainersSuitable containers made of ma-terial resistant to corrosion and a chang

36、e in mass upon repeatedheating, cooling, and cleaning. One container is needed foreach water content determination.7.4 Container Handling ApparatusGloves or suitableholder for moving hot containers after drying.7.5 Desiccator (optional)A desiccator cabinet or jar ofsuitable size containing silica ge

37、l, anhydrous calciumD4959 162phosphate, or equivalent. It is preferable to use a desiccant thatchanges color to indicate that it needs reconstitution.7.6 Miscellaneous (as needed)Mixing tools such asspatulas, spoons, etc.; eye protection, such as safety glasses orgoggles; dry light-weight paper of t

38、issue, and knives.8. Hazards8.1 Container holders or gloves are recommended for han-dling hot containers. Some soil types can retain considerableheat, and serious burns could result from improper handling.8.2 Suitable eye protection such as safety glasses or gogglesis recommended due to the possibil

39、ity of particle shatteringduring heating, mixing, or mass determinations.8.3 Highly organic soils, and soils containing oil or othercontaminants may ignite during drying with direct heatsources. Means for smothering flames to prevent operatorinjury or equipment damage should be available during test

40、ing.Fumes given off from contaminated soils or wastes may betoxic, and should be vented accordingly.8.4 Due to the possibility of steam explosions, or thermalstress shattering of porous or brittle aggregates, a ventedcovering over the sample container may be appropriate toprevent operator injury or

41、equipment damage. This also pre-vents scattering of the test specimen during the drying cyclewhile aiding in uniform heating of the specimen.9. Samples9.1 Perform the water content determination as soon aspractical after sampling to prevent water loss and damage topotentially corrodible containers.9

42、.2 Prior to testing, store samples in non-corrodible airtightcontainers at a temperature between approximately 3 and 30Cand in an area that prevents direct exposure to sunlight.10. Test Specimens10.1 Select a representative portion of the total sample. If alayered soil or more than one soil type is

43、encountered, select anaverage portion or individual portions of each, and note whichportion(s) were tested in the report of the results.10.1.1 For cohesionless soils, mix the material thoroughly,and select a test specimen having a mass of moist material inaccordance with Table 1.10.1.2 For cohesive

44、soils, remove about 3 mm of materialfrom the exposed periphery of the sample and slice theremaining specimen in half (to check if the material is layered),prior to selecting a test specimen having a moist mass inaccordance with Table 1. If the soil is layered, see 10.1.Breaking or cutting of cohesiv

45、e samples to approximately 6mm particles speeds drying and prevents crusting or overheat-ing the surface while drying the interior.10.2 Using a test specimen smaller than the minimum massindicated in Table 1 requires discretion, though it may beadequate for the purpose of the test. Note a specimen h

46、aving amass less than the previously indicated value in the report ofresults.NOTE 2When working with a small sample containing a relativelylarge coarse-grained particle, it may be appropriate not to include thisparticle in the test specimen, depending on the use of test results. If thisis done, such

47、 exclusion should be noted in the report of the results.10.3 When the result of a water content determination bythe use of this test method is to be compared to the results ofanother method, such as Test Methods D2216, obtain a secondspecimen during selection of the specimen for this comparison.Take

48、 precautions to obtain a specimen that represents the samewater content as closely as possible. Protect the comparisonspecimens from water loss by transporting and storing thespecimens in sealed containers. A correction factor can bedetermined for use on subsequent water content determinationson the

49、 same soil types from the same site when the differenceis relatively constant using several comparisons. Check thecorrection factor on a regular, specified basis. Recognize thatdifferent technicians, heat sources, and such may result indifferent correction factors.11. Conditioning11.1 Prepare, process, and test all specimens as quickly aspossible to minimize unrecorded moisture loss.11.2 Cut or break up the soil into small size aggregations toaid in obtaining more uniform drying of the specimen, takingcare to avoid any loss of soil.11.3 If the specimens are not being