1、Designation: C702/C702M 11American Association StateHighway and TransportationOfficials Standard: T 248Standard Practice forReducing Samples of Aggregate to Testing Size1This standard is issued under the fixed designation C702/C702M; the number immediately following the designation indicates the yea
2、rof original adoption or, in the case of revision, the year of last revision. A number 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 Departme
3、nt of Defense.1. Scope1.1 This practice covers three methods for the reduction oflarge samples of aggregate to the appropriate size for testingemploying techniques that are intended to minimize variationsin measured characteristics between the test samples so se-lected and the large sample.1.2 The v
4、alues stated in either SI units or inch-pound unitsare to be regarded separately as standard. The values stated ineach system may not be exact equivalents; therefore, eachsystem shall be used independently of the other. Combiningvalues from the two systems may result in non-conformancewith the stand
5、ard.NOTE 1Sieve size is identified by its standard designation in Speci-fication E11. The alternative designation given in parentheses is forinformation only and does not represent a different standard sieve size.1.3 This standard does not purport to address all of thesafety concerns, if any, associ
6、ated 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:2C125 Terminology Relating to Concrete and Concrete Ag-grega
7、tesC128 Test Method for Density, Relative Density (SpecificGravity), and Absorption of Fine AggregateD75 Practice for Sampling AggregatesE11 Specification for Woven Wire Test Sieve Cloth and TestSieves3. Terminology3.1 DefinitionsThe terms used in this practice are definedin Terminology C125.4. Sign
8、ificance and Use4.1 Specifications for aggregates require sampling portionsof the material for testing. Other factors being equal, largersamples will tend to be more representative of the total supply.This practice provides procedures for reducing the largesample obtained in the field or produced in
9、 the laboratory to aconvenient size for conducting a number of tests to describe thematerial and measure its quality in a manner that the smallertest sample portion is most likely to be a representation of thelarger sample, and thus of the total supply. Failure to carefullyfollow the procedures in t
10、his practice could result in providinga nonrepresentative sample to be used in subsequent testing.The individual test methods provide for minimum amount ofmaterial to be tested.4.2 Under certain circumstances, reduction in size of thelarge sample prior to testing is not recommended. Substantialdiffe
11、rences between the selected test samples sometimes can-not be avoided, as for example, in the case of an aggregatehaving relatively few large size particles in the sample. Thelaws of chance dictate that these few particles may beunequally distributed among the reduced size test samples.Similarly, if
12、 the test sample is being examined for certaincontaminants occurring as a few discrete fragments in onlysmall percentages, caution should be used in interpretingresults from the reduced size test sample. Chance inclusion orexclusion of only one or two particles in the selected testsample may importa
13、ntly influence interpretation of the charac-teristics of the original sample. In these cases, the entireoriginal sample should be tested.5. Selection of Method5.1 Fine AggregateReduce the size of samples of fineaggregate that are drier than the saturated-surface-dry condi-tion (Note 2) using a mecha
14、nical splitter according to MethodA. Reduce the size of samples having free moisture on the1This practice is under the jurisdiction of ASTM Committee C09 on Concreteand ConcreteAggregates and is the direct responsibility of Subcommittee C09.20 onNormal Weight Aggregates.Current edition approved Aug.
15、 1, 2011. Published September 2011. Originallyapproved in 1971. Last previous edition approved in 2003 as C70298(2003). DOI:10.1520/C0702_C0702M-11.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandar
16、ds 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.particle surfaces by quartering according to Method B, or bytreating as a miniature stockpile as d
17、escribed in Method C.5.1.1 If the use of Method B or Method C is desired, and thesample does not have free moisture on the particle surfaces,moisten the sample to obtain free moisture on the particlesurfaces, mix thoroughly, and then reduce the sample size.5.1.2 If use of Method A is desired and the
18、 sample has freemoisture on the particle surfaces, dry the entire sample to atleast the saturated-surface-dry condition, using temperaturesthat do not exceed those specified for any of the testscontemplated, and then reduce the sample size.Alternatively, ifthe moist sample is very large, make a prel
19、iminary split usinga mechanical splitter having chute openings of 38 mm 112 in.or more in width to reduce the sample to not less than 5 kg 10lb. Dry the portion so obtained, and reduce it to test samplesize using Method A.NOTE 2The method of determining the saturated-surface-dry condi-tion is descri
20、bed in Test Method C128. As a quick approximation, if thefine aggregate will retain its shape when molded in the hand, it may beconsidered to be wetter than saturated-surface-dry.5.2 Coarse Aggregates and Mixtures of Coarse and FineAggregatesReduce the sample using a mechanical splitter inaccordance
21、 with Method A (preferred method) or by quarteringin accordance with Method B. The miniature stockpile MethodC is not permitted for coarse aggregates or mixtures of coarseand fine aggregates.6. Sampling6.1 Obtain samples of aggregate in the field in accordancewith Practice D75, or as required by ind
22、ividual test methods.When tests for sieve analysis only are contemplated, the size ofthe field sample listed in Practice D75 is usually adequate.When additional tests are to be conducted, the user shall besatisfied that the initial size of the field sample is adequate toaccomplish all intended tests
23、. Use similar procedures foraggregate produced in the laboratory.METHOD AMECHANICAL SPLITTER7. Apparatus7.1 Sample SplitterSample splitters shall have an evennumber of equal width chutes, but not less than a total of eightfor coarse aggregate, or twelve for fine aggregate, whichdischarge alternately
24、 to each side of the splitter. For coarseaggregate and mixed aggregate, the minimum width of theindividual chutes shall be approximately 50 % larger than thelargest particles in the sample to be split (Note 3). For dry fineaggregate in which the entire sample will pass the 9.5-mm(38-in.) seive, a sp
25、litter having chutes 12.5 to 20 mm 12 to34in. wide shall be used. The splitter shall be equipped with tworeceptacles to hold the two halves of the sample followingsplitting. It shall also be equipped with a hopper or straight-edged pan which has a width equal to or slightly less than theover-all wid
26、th of the assembly of chutes, by which the samplemay be fed at a controlled rate to the chutes. The splitter andaccessory equipment shall be so designed that the sample willflow smoothly without restriction or loss of material (see Fig.1 and Fig. 2).NOTE 3Mechanical splitters are commonly available
27、in sizes ad-equate for coarse aggregate having the largest particle not over 37.5 mm112 in.8. Procedure8.1 Place the original sample in the hopper or pan anduniformly distribute it from edge to edge, so that when it isintroduced into the chutes, approximately equal amounts willflow through each chut
28、e. Introduce the sample at a rate so as toallow it to flow freely through the chutes and into thereceptacles below. Reintroduce the portion of the sample in oneof the receptacles into the splitter as many times as necessaryto reduce the sample to the size specified for the intended test.Reserve the
29、portion of material collected in the other receptaclefor reduction in size for other tests, when required.FIG. 1 Large Sample Splitter for Coarse AggregateC702/C702M 112METHOD BQUARTERING9. Apparatus9.1 Apparatus shall consist of a straight-edged scoop,shovel, or trowel; a broom or brush; and a canv
30、as blanketapproximately 2 by 2.5 m 6 by 8 ft.10. Procedure10.1 Use either the procedure described in 10.1.1 or 10.1.2or a combination of both.10.1.1 Place the original sample on a hard, clean, levelsurface where there will be neither loss of material nor theaccidental addition of foreign material. M
31、ix the materialthoroughly by turning the entire sample over three times. Withthe last turning, shovel the entire sample into a conical pile bydepositing each shovelful on top of the preceding one. Care-fully flatten the conical pile to a uniform thickness anddiameter by pressing down the apex with a
32、 shovel so that eachquarter sector of the resulting pile will contain the materialoriginally in it. The diameter should be approximately four toeight times the thickness. Divide the flattened mass into fourequal quarters with a shovel or trowel and remove twodiagonally opposite quarters, including a
33、ll fine material, andbrush the cleared spaces clean. Successively mix and quarterthe remaining material until the sample is reduced to thedesired size (Fig. 3).NOTE Small Sample Splitters for Fine Aggregate. May be constructed as either closed or open type. Closed type is preferred.FIG. 2 Sample Spl
34、itters (Riffles)FIG. 3 Quartering on a Hard, Clean Level SurfaceC702/C702M 11310.1.2 As an alternative to the procedure described in10.1.1, when the floor surface is uneven, place the field sampleon a canvas blanket and mix with a shovel as described in10.1.1, or by alternately lifting each corner o
35、f the canvas andpulling it over the sample toward the diagonally oppositecorner causing the material to be rolled. Flatten the pile asdescribed in 10.1.1. Divide the sample as described in 10.1.1,or if the surface beneath the blanket is uneven, insert a stick orpipe beneath the blanket and under the
36、 center of the pile, thenlift both ends of the stick, dividing the sample into two equalparts. Remove the stick leaving a fold of the blanket betweenthe divided portions. Insert the stick under the center of the pileat right angles to the first division and again lift both ends ofthe stick, dividing
37、 the sample into four equal parts. Removetwo diagonally opposite quarters, being careful to clean thefines from the blanket. Successively mix and quarter theremaining material until the sample is reduced to the desiredsize (Fig. 4).METHOD CMINIATURE STOCKPILE SAMPLING(DAMP FINE AGGREGATE ONLY)11. Ap
38、paratus11.1 Apparatus shall consist of a straight-edged scoop,shovel, or trowel for mixing the aggregate, and either a smallsampling thief, small scoop, or spoon for sampling.12. Procedure12.1 Place the original sample of damp fine aggregate on ahard clean, level surface where there will be neither
39、loss ofmaterial nor the accidental addition of foreign material. Mixthe material thoroughly by turning the entire sample over threetimes. With the last turning, shovel the entire sample into aconical pile by depositing each shovelful on top of thepreceding one. If desired, flatten the conical pile t
40、o a uniformthickness and diameter by pressing down the apex with ashovel so that each quarter sector of the resulting pile willcontain the material originally in it. Obtain a sample for eachtest by selecting at least five increments of material at randomlocations from the miniature stockpile, using
41、any of thesampling devices described in 11.1.13. Keywords13.1 aggregate; aggregatecoarse; aggregatefine; fieldtestingaggregate; samplingaggregates; sample reduction;specimen preparationC702/C702M 114ASTM International takes no position respecting the validity of any patent rights asserted in connect
42、ion with any item mentionedin this standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsibl
43、e technical committee and must be reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful cons
44、ideration at a meeting of theresponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 B
45、arr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org). Permission rights to photocopy the standard may also be secured from the ASTM website (www.astm.org/COPYRIGHT/).FIG. 4 Quartering on a Canvas BlanketC702/C702M 115
copyright@ 2008-2019 麦多课文库（www.mydoc123.com）网站版权所有
备案/许可证编号：苏ICP备17064731号-1