1、Designation: C 702 98 (Reapproved 2003)American Association StateHighway and TransportationOfficials Standard: T 248Standard Practice forReducing Samples of Aggregate to Testing Size1This standard is issued under the fixed designation C 702; the number immediately following the designation indicates
2、 the year oforiginal adoption or, in the case of revision, the year of 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. Scope1.1 This practice covers three methods for the red
3、uction 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 values stated in SI units are to be regarded as thestandard.1.3 This stan
4、dard 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 health practices and determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 A
5、STM Standards:C 125 Terminology Relating to Concrete and ConcreteAggregates2C 128 Test Method for Density, Relative Density (SpecificGravity), and Absorption of Fine Aggregate2D 75 Practice for Sampling Aggregates33. Terminology3.1 DefinitionsThe terms used in this practice are definedin Terminology
6、 C 125.4. Significance 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
7、or produced in 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 p
8、rocedures in this 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. Su
9、bstantialdifferences 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
10、.Similarly, if 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 testsamp
11、le may importantly 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 1)
12、 using a mechanical splitter according to MethodA. Reduce the size of samples having free moisture on theparticle surfaces by quartering according to Method B, or bytreating as a miniature stockpile as described in Method C.5.1.1 If the use of Method B or Method C is desired, and thesample does not
13、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 sample has freemoisture on the particle surfaces, dry the entire sample to atleast the saturated
14、-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 preliminary split usinga mechanical splitter having chute openings of 38 mm (112 in.)or more in widt
15、h to reduce the sample to not less than 5000 g.Dry the portion so obtained, and reduce it to test sample sizeusing Method A.NOTE 1The method of determining the saturated-surface-dry condi-tion is described in Test Method C 128. As a quick approximation, if the1This practice is under the jurisdiction
16、 of ASTM Committee C09 on Concreteand Concrete Aggregates and is the direct responsibility of Subcommittee C09.20 onNormal Weight Aggregates.Current edition approved May 10, 1998. Published December 1998. Originallyapproved in 1971. Last previous edition approved in 1993 as C 702 93.2Annual Book of
17、ASTM Standards, Vol 04.02.3Annual Book of ASTM Standards, Vol 04.03.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.fine aggregate will retain its shape when molded in the hand, it may beconsidered to be wetter than saturated-surface
18、-dry.5.2 Coarse Aggregates and Mixtures of Coarse and FineAggregatesReduce the sample using a mechanical splitter inaccordance 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
19、 fine aggregates.6. Sampling6.1 Obtain samples of aggregate in the field in accordancewith Practice D 75, or as required by individual test methods.When tests for sieve analysis only are contemplated, the size ofthe field sample listed in Practice D 75 is usually adequate.When additional tests are t
20、o be conducted, the user shall besatisfied that the initial size of the field sample is adequate toaccomplish all intended tests. Use similar procedures foraggregate produced in the laboratory.METHOD AMECHANICAL SPLITTER7. Apparatus7.1 Sample SplitterSample splitters shall have an evennumber of equa
21、l width chutes, but not less than a total of eightfor coarse aggregate, or twelve for fine aggregate, whichdischarge alternately to each side of the splitter. For coarseaggregate and mixed aggregate, the minimum width of theindividual chutes shall be approximately 50 % larger than thelargest particl
22、es in the sample to be split (Note 2). For dry fineaggregate in which the entire sample will pass the 9.5-mm(38-in.) seive, a splitter 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 followingsplitti
23、ng. It shall also be equipped with a hopper or straight-edged pan which has a width equal to or slightly less than theover-all width 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 w
24、illflow smoothly without restriction or loss of material (see Fig.1 and Fig. 2).NOTE 2Mechanical splitters are commonly available in sizes ad-equate for coarse aggregate having the largest particle not over 37.5 mm(112 in.).8. Procedure8.1 Place the original sample in the hopper or pan anduniformly
25、distribute it from edge to edge, so that when it isintroduced into the chutes, approximately equal amounts willflow through each chute. 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
26、receptacles into the splitter as many times as necessaryto reduce the sample to the size specified for the intended test.Reserve the portion of material collected in the other receptaclefor reduction in size for other tests, when required.METHOD BQUARTERING9. Apparatus9.1 Apparatus shall consist of
27、a straight-edged scoop,shovel, or trowel; a broom or brush; and a canvas 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 ne
28、ither loss of material nor theaccidental addition of foreign material. Mix 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
29、pile to a uniform thickness anddiameter by pressing down the apex with a shovel so that eachFIG. 1 Large Sample Splitter for Coarse AggregateC 702 98 (2003)2quarter sector of the resulting pile will contain the materialoriginally in it. The diameter should be approximately four toeight times the thi
30、ckness. Divide the flattened mass into fourequal quarters with a shovel or trowel and remove twodiagonally opposite quarters, including all fine material, andbrush the cleared spaces clean. Successively mix and quarterthe remaining material until the sample is reduced to thedesired size (Fig. 3).10.
31、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 of the canvas andpulling it over the sample toward the diagonally oppositecorner c
32、ausing 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 center of the pile, thenlift both ends of the stick, dividing the sample into tw
33、o 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 the sample into four equal parts. Removetwo diagonally opposite quarters, being
34、careful to clean thefines from the blanket. Successively mix and quarter theremaining material until the sample is reduced to the desiredsize (Fig. 4).NOTE Small Sample Splitters for Fine Aggregate. May be constructed as either closed or open type. Closed type is preferred.FIG. 2 Sample Splitters (R
35、iffles)FIG. 3 Quartering on a Hard, Clean Level SurfaceC 702 98 (2003)3METHOD CMINIATURE STOCKPILE SAMPLING(DAMP FINE AGGREGATE ONLY)11. Apparatus11.1 Apparatus shall consist of a straight-edged scoop,shovel, or trowel for mixing the aggregate, and either a smallsampling thief, small scoop, or spoon
36、 for sampling.12. Procedure12.1 Place the original sample of damp fine aggregate on ahard clean, level surface where there will be neither loss ofmaterial nor the accidental addition of foreign material. Mixthe material thoroughly by turning the entire sample over threetimes. With the last turning,
37、shovel the entire sample into aconical pile by depositing each shovelful on top of thepreceding one. If desired, flatten the conical pile to 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
38、 it. Obtain a sample for eachtest by selecting at least five increments of material at randomlocations from the miniature stockpile, using any of thesampling devices described in 11.1.13. Keywords13.1 aggregate; aggregatecoarse; aggregatefine; fieldtestingaggregate; samplingaggregates; sample reduct
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41、r for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration 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 k
42、nown to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr 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).FIG. 4 Quartering on a Canvas BlanketC 702 98 (2003)4
