ASTM D4959-2007 Standard Test Method for Determination of Water (Moisture) Content of Soil By Direct Heating《用直接加热法测定土壤中含水量的标准试验方法》.pdf

《ASTM D4959-2007 Standard Test Method for Determination of Water (Moisture) Content of Soil By Direct Heating《用直接加热法测定土壤中含水量的标准试验方法》.pdf》由会员分享，可在线阅读，更多相关《ASTM D4959-2007 Standard Test Method for Determination of Water (Moisture) Content of Soil By Direct Heating《用直接加热法测定土壤中含水量的标准试验方法》.pdf（6页珍藏版）》请在麦多课文档分享上搜索。

1、Designation: D 4959 07Standard Test Method forDetermination of Water (Moisture) Content of Soil By DirectHeating1This standard is issued under the fixed designation D 4959; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year o

2、f last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope*1.1 This test method covers procedures for determining thewater (moisture) content of soils by drying with direct heat

3、,such as using a hotplate, stove, blowtorch, etc.1.2 This test method can be used as a substitute for TestMethods D 2216 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

4、Test Methods D 2216 arise, Test Methods D 2216 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 co

5、ntain dissolvedsolids, (such as salt in the case of marine deposits), this testmethod may not yield reliable water content values.1.5 The values stated in SI units are to be regarded asstandard.1.6 Refer to Practice D 6026 for guidance concerning theuse of significant figures. This is important if t

6、he water contentwill be used to calculate other relationships such as moist massto dry mass or vice versa, wet unit weight to dry unit weight orvice versa, and total density to dry density or vice versa. Forexample, if four significant digits are required in any of theabove calculations, then the wa

7、ter content has to be recorded tothe nearest 0.1%. This occurs since 1 plus the water content(not in percent) will have four significant digits, While, if threesignificant digits are acceptable, then the water content can berecorded to the nearest 1%1.7 This standard does not purport to address all

8、of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:2D 653 Terminology Rela

9、ting to Soil, Rock, and ContainedFluidsD 2216 Test Methods for Laboratory Determination of Wa-ter (Moisture) Content of Soil and Rock by MassD 3740 Practice for Minimum Requirements for AgenciesEngaged in the Testing and/or Inspection of Soil and Rockas Used in Engineering Design and ConstructionD 4

10、753 Guide for Evaluating, Selecting, and SpecifyingBalances and Standard Masses for Use in Soil, Rock, andConstruction Materials TestingD 6026 Practice for Using Significant Digits in Geotechni-cal Data3. Terminology3.1 DefinitionsAll definitions are in accordance with Ter-minology D 653.3.2 Definit

11、ions 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 specimen container, such as provided by a hotplate, gas stove or burner, heatlamps, or other heat sources.Direct applicati

12、on of heat by flame to the specimen is notappropriate.3.2.2 water (moisture) contentthe ratio, expressed as apercentage, of the mass of water in a given mass of soil to themass of the solid particles.4. Summary of Test Method4.1 A moist soil specimen is placed in a suitable containerand its mass is

13、determined. It is then subjected 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.1This test method is under the jurisdiction ofASTM

14、 Committee D18 on Soil andRock and is the direct responsibility of Subcommittee D18.08 on Special andConstruction Control Tests.Current edition approved Feb. 1, 2007. Published March 2007. Originallyapproved in 1989. Last previous edition approved in 2000 as D 4959 002For referenced ASTM standards,

15、visit the ASTM website, www.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.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM Internation

16、al, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.2 The difference between the masses of the moist speci-men and the dried specimen is used as the mass of watercontained in the specimen. The water content (expressed as apercentage) is determined by dividing th

17、e 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 estimate drying time for subsequent tests ofthe same soil type using the same size specimen and dryingapparatus.5. Significance and Use5.

18、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 D 2216 for water contentdetermination can be time consuming and there are occasionswhen a more expedient method is desirable. Drying by directheating is

19、 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 watercontent, and in the determination of in-place dry unit weight ofsoils.5.2 The principal objection to the use of the direct heatingfor

20、water content determination is the possibility of overheat-ing the soil, thereby yielding a water content higher than wouldbe determined by Test Methods D 2216. While not eliminatingthis possibility, the incremental drying procedure in this testmethod will minimize its effects. Some heat sources hav

21、esettings 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 heat distribution.5.3 The behavior of a soil when subjected to direct heatingis dependent on its mineralogical composition, and as a r

22、esult,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 to 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,

23、 a correction factor canusually be determined by making several comparisons betweenthe results of this test method and Test Methods D 2216.Acorrection factor is valid when the difference is consistent forseveral comparisons, and is reconfirmed on a regular specifiedbasis.5.5 This test method may not

24、 be appropriate when preciseresults are required, or when minor variations in water contentwill affect the results of other test methods, such as borderlinesituations where small variations in the measured water contentcould affect acceptance or rejection.5.6 This test method is not appropriate for

25、specimens knownto contain flammable organics or contaminants, and other testmethods should be utilized in these situations.NOTE 1The quality of the results produced by this test method isdependent on the competence of the personnel performing it and thesuitability of the equipment and facilities use

26、d. Agencies that meet thecriteria of Practice D 3740 are generally considered capable of competentand objective testing/sampling/inspection. Users of this test method arecautioned that compliance with Practice D 3740 does not in itself ensurereliable results . Reliable results depend on many factors

27、; Practice D 3740provides a means of evaluating some of those factors.6. Interferences6.1 When testing sand and gravel size particles, additionalcare must be taken to avoid the possibility of particle shatter-ing.6.2 Due to the localized high temperatures in the soil duringtesting, the physical char

28、acteristics of the soil may be altered.Degradation of individual particles may occur, along withvaporization, chemical transition, or loss of organics. There-fore, specimens used in this test method should not be used forother tests subsequent to drying.7. Apparatus7.1 Direct Heat SourceAny source o

29、r 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, and hotplates, blowtorches, heatlamps, hair driers, space heaters, etc. Heat sources that directlyapply open flame to the specime

30、n 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 BalancesA balance having a minimum capacity of 2Kg, and meeting the requirements of Guide D 4753 for abalance of 0.1-g readability.7.3 Specimen ContainersSuitable

31、 containers made of ma-terial resistant to corrosion and a change 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 Miscellaneous (as nee

32、ded)Mixing tools such as spatu-las, spoons, etc.; eye protection, such as safety glasses orgoggles; cigarette papers, 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 im

33、proper handling.8.2 Suitable eye protection such as safety glasses or gogglesis recommended due to the possibility 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 heatsou

34、rces. Means for smothering flames to prevent operatorinjury or equipment damage should be available during testing.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

35、brittle aggregates, a ventedcovering over the sample container may be appropriate toprevent operator injury or 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 determin

36、ation as soon aspractical after sampling to prevent water loss and damage topotentially corrodible containers.D49590729.2 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.

37、Test Specimens10.1 Select a representative portion of the total sample. If alayered soil or more than one soil type is 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 bulk samples, select the test spec

38、imen from thematerial after it has been thoroughly mixed. The mass of moistmaterial selected shall be in accordance with Table 1.10.1.2 For small samples, select a representative portion inaccordance with the following procedure:10.1.2.1 For cohesionless soils, mix the material thoroughly,and select

39、 a test specimen having a mass of moist material inaccordance with Table 1.10.1.2.2 For cohesive 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 the test specimen. If the soi

40、l is layered, see10.1. Breaking or cutting of cohesive samples to approximately6 mm particles speeds drying and prevents crusting or over-heating 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 bead

41、equate for the purpose of the test. Note a specimen having 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, depen

42、ding on the use of test results. If thisis done, such 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 D 2216, obtain a secondspecimen dur

43、ing selection of the specimen for this comparison.Take 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 fo

44、r use on subsequent water content determinationson the 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

45、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

46、the specimens are not being tested immediately,place the specimens in containers that can be closed and storedin an area not exposed to direct sunlight, to prevent loss ofmoisture prior to initial mass determinations.12. Procedure12.1 Determine the mass of a clean, dry container, andrecord.12.2 Plac

47、e the soil specimen in the container, and immedi-ately determine and record the mass of the soil and container.12.3 Apply heat to the soil specimen and container, takingcare to avoid localized overheating. Continue heating whilestirring the specimen to obtain even heat distribution. Continueapplicat

48、ion of heat until the specimen first appears dry. Acomparatively uniform color should result. Avoid localizedburnt or darkened appearance of any part of the soil byintermittent mixing and stirring.12.3.1 Experience with a particular soil type indicates whenshorter or longer initial drying periods ca

49、n be used withoutoverheating.NOTE 3A piece of dry, light-weight paper or tissue, such as cigarettepaper, placed on the surface of the apparently dry soil will curl or rippleif the soil still contains significant water.12.4 After an initial heating period has been completed (soilappears dry), remove the container and soil from the heatsource and cool to allow handling and prevent damage to thebalance. Determine and record the mass of the soil andcontainer.12.5 Return the container and soil to the heat source for anadditional application of heat.12.6 With a small spatula o