1、Designation: C702/C702M 11C702/C702M 18 American 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 ind
2、icates the yearof 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 o
3、f the U.S. Department of Defense.1. Scope1.1 This practice covers three methods for the reduction of large samples of aggregate to the appropriate size for testingemployingtesting. These techniques that are intended to minimize variations in measured characteristics between the test samplesso select
4、ed and the large sample.1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in eachsystem may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from thetwo systems may resu
5、lt in non-conformance with the standard.NOTE 1Sieve size is identified by its standard designation in Specification E11. The alternative designation given in parentheses is for informationonly and does not represent a different standard sieve size.1.3 This standard does not purport to address all of
6、 the safety concerns, if any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitations prior to use.1.4 This international standard was deve
7、loped in accordance with internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Docume
8、nts2.1 ASTM Standards:2C125 Terminology Relating to Concrete and Concrete AggregatesC128 Test Method for Relative Density (Specific Gravity) and Absorption of Fine AggregateD75 Practice for Sampling AggregatesE11 Specification for Woven Wire Test Sieve Cloth and Test Sieves3. Terminology3.1 Definiti
9、onsThe terms used in this practice are defined in Terminology C125.4. Significance and Use4.1 Specifications for aggregates require sampling obtaining representative portions of the supply material for testing. Otherfactors being equal, larger samples will tend to be more representative of the total
10、 supply. This practice provides procedures forreducing the large sample obtained in the field, or produced in the laboratory, to a convenient size for conducting a number of teststo describe the material and measure its quality in a manner that the smaller test sample portion is most likely to be a
11、representationof the larger sample, and thus of the total supply. descriptive and quality tests. Failure to carefully follow the procedures in thispractice could result in providing a nonrepresentativenon-representative sample to be used in subsequent testing. The individualtest methods provide for
12、minimum amount of material to be tested.1 This practice is under the jurisdiction ofASTM Committee C09 on Concrete and ConcreteAggregates and is the direct responsibility of Subcommittee C09.20 on NormalWeight Aggregates.Current edition approved Aug. 1, 2011Feb. 1, 2018. Published September 2011Marc
13、h 2018. Originally approved in 1971. Last previous edition approved in 20032011 asC70298(2003).C702/C702M11. DOI: 10.1520/C0702_C0702M-11.10.1520/C0702_C0702M-18.2 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at serviceastm.org. For Annual Book o
14、f ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.This document 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 technical
15、ly possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as 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 C
16、700, West Conshohocken, PA 19428-2959. United States14.2 Under certain circumstances, reduction in size of the large sample prior to testing is not recommended. Substantialdifferences between the selected test samples sometimes cannot be avoided, as for example, in the case of an aggregate havingrel
17、atively few large size particles in the sample. The laws of chance dictate that these few particles may be unequally distributedamong the reduced size test samples. Similarly, if the test sample is being examined for certain contaminants occurring as a fewdiscrete fragments in only small percentages
18、, caution should be used in interpreting results from the reduced size test sample.Chance inclusion or exclusion of only one or two particles in the selected test sample may importantly influence interpretation ofthe characteristics of the original sample. In these cases, the entire original sample
19、should be tested.5. Selection of Method5.1 Fine AggregateReduce the size of samples of fine aggregate that are drier than the saturated-surface-dry condition (Note2) using a mechanical splitter according to Method A. Reduce the size of samples having free moisture on the particle surfacesby quarteri
20、ng according to Method B, or by treating as a miniature stockpile as described in Method C.5.1.1 If the use of Method B or Method C is desired, and the sample does not have free moisture on the particle surfaces,moisten the sample to obtain free moisture on the particle surfaces, mix thoroughly, and
21、 then reduce the sample size.5.1.2 If use of Method A is desired and the sample has free moisture on the particle surfaces, dry the entire sample to at leastthe saturated-surface-dry condition, using temperatures that do not exceed those specified for any of the tests contemplated, andthen reduce th
22、e sample size. Alternatively, if the moist sample is very large, make a preliminary split using a mechanical splitterhaving chute openings of 38 mm 112 in. or more in width to reduce the sample to not less than 5 kg 10 lb. Dry the portion soobtained, and reduce it to test sample size using Method A.
23、NOTE 2The method of determining the saturated-surface-dry condition is described in Test Method C128. As a quick approximation, if the fineaggregate will retain its shape when molded in the hand, it may be considered to be wetter than saturated-surface-dry.5.2 Coarse Aggregates and Mixtures of Coars
24、e and Fine AggregatesReduce the sample using a mechanical splitter inaccordance with Method A (preferred method) or by quartering in accordance with Method B. The miniature stockpile Method Cis not permitted for coarse aggregates or mixtures of coarse and fine aggregates.6. Sampling6.1 Obtain sample
25、s of aggregate in the field in accordance with Practice D75, or as required by individual test methods. Whentests for sieve analysis only are contemplated, the size of the field sample listed in Practice D75 is usually adequate. Whenadditional tests are to be conducted, the user shall be satisfied t
26、hat the initial size of the field sample is adequate to accomplishall intended tests. Use similar procedures for aggregate produced in the laboratory.METHOD AMECHANICAL SPLITTER7. Apparatus7.1 Sample SplitterSample splitters shall have an even number of equal width chutes, but not less than a total
27、of eight forcoarse aggregate, or twelve for fine aggregate, which discharge alternately to each side of the splitter. For coarse aggregate andmixed aggregate, the minimum width of the individual chutes shall be approximately 50 % larger than the largest particles in thesample to be split (Note 3). F
28、or dry fine aggregate in which the entire sample will pass the 9.5-mm (38-in.) seive,sieve, a splitterhaving chutes 12.5 to 20 mm 12 to 34 in. wide shall be used. The splitter shall be equipped with a minimum of two receptaclesto hold the two halves of the sample following splitting. It shall also b
29、e equipped with a hopper or straightedgedstraight-edged panwhich has a width equal to or slightly less than the over-alloverall width of the assembly of chutes, chute assembly, by which thesample may be fed at a controlled rate to the chutes. The splitter and accessory equipment shall be so designed
30、 that the samplewill flow smoothly without restriction or loss of material (see Fig. 1 and Fig. 2).NOTE 3Mechanical splitters are commonly available in sizes adequate for coarse aggregate having the largest particle not over 37.550.0 mm12 in.12 in.8. Procedure8.1 Place the original sample in the hop
31、per or pan and uniformly distribute it from edge to edge, so that when it is introducedinto the chutes, approximately equal amounts will flow through each chute. Introduce the sample at a rate so as to allow it to flowfreely through the chutes and into the receptacles below. Reintroduce the portion
32、of the sample in one of the receptacles into thesplitter as many times as necessary necessary, alternating each side, to reduce the sample to the size specified for the intended test.Reserve the portion of material collected in the other receptacle for reduction in size for other tests, when require
33、d.METHOD BQUARTERING9. Apparatus9.1 Apparatus shall consist of a straight-edged scoop, shovel, or trowel; a broom or brush; and a canvas blanket approximately2 by 2.5 m 6 by 8 ft.C702/C702M 18210. Procedure10.1 Use either the procedure described in 10.1.1 or 10.1.2 or a combination of both.10.1.1 Pl
34、ace the original sample on a hard, clean, level surface where there will be neither loss of material nor the accidentaladdition of foreign material. Mix the material thoroughly by turning the entire sample over three times.With the last turning, shovelthe entire sample into a conical pile by deposit
35、ing each shovelful on top of the preceding one. Carefully flatten the conical pileto a uniform thickness and diameter by pressing down the apex with a shovel so that each quarter sector of the resulting pile willcontain the material originally in it. The diameter should be approximately four to eigh
36、t times the thickness. Divide the flattenedmass into four equal quarters with a shovel or trowel and remove two diagonally opposite quarters, including all fine material, andbrush the cleared spaces clean. Successively mix and quarter the remaining material until the sample is reduced to the desired
37、 size(Fig. 3).10.1.2 As an alternative to the procedure described in 10.1.1, when the floor surface is uneven, place the field sample on acanvas blanket and mix with a shovel as described in 10.1.1, or by alternately lifting each corner of the canvas and pulling it overFIG. 1 Large Sample Splitter f
38、or Coarse AggregateNOTE 1 Small Sample Splitters for Fine Aggregate. May be constructed as either closed or open type. Closed type is preferred.FIG. 2 Sample Splitters (Riffles)C702/C702M 183the sample toward the diagonally opposite corner causing the material to be rolled. Flatten the pile as descr
39、ibed in 10.1.1. Dividethe sample as described in 10.1.1, or if the surface beneath the blanket is uneven, insert a stick or pipe beneath the blanket andunder the center of the pile, then lift both ends of the stick, dividing the sample into two equal parts. Remove the stick leavinga fold of the blan
40、ket between the divided portions. Insert the stick under the center of the pile at right angles to the first divisionand again lift both ends of the stick, dividing the sample into four equal parts. Remove two diagonally opposite quarters, beingcareful to clean the fines from the blanket. Successive
41、ly mix and quarter the remaining material until the sample is reduced to thedesired size (Fig. 4).METHOD 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 small samplin
42、gthief, small scoop, or spoon for sampling.FIG. 3 Quartering on a Hard, Clean Level SurfaceFIG. 4 Quartering on a Canvas BlanketC702/C702M 18412. Procedure12.1 Place the original sample of damp fine aggregate on a hard clean, level surface where there will be neither loss of materialnor the accident
43、al addition of foreign material. Mix the material thoroughly by turning the entire sample over three times. Withthe last turning, shovel the entire sample into a conical pile by depositing each shovelful on top of the preceding one. If desired,flatten the conical pile to a uniform thickness and diam
44、eter by pressing down the apex with a shovel so that each quarter sectorof the resulting pile will contain the material originally in it. Obtain a sample for each test by selecting at least five incrementsof material at random locations fromaround the miniature stockpile, using any of the sampling d
45、evices described in 11.1.C702/C702M 18513. Keywords13.1 aggregate; aggregatecoarse; aggregatefine; field testingaggregate; samplingaggregates; sample reduction; speci-men preparationC702/C702M 186ASTM International takes no position respecting the validity of any patent rights asserted in connection
46、 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 responsible t
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48、ation 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 Barr
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