1、Designation:C702/C702M11American 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 yearof
2、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 U.S.Department of
3、 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 values
4、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 standard.NOTE1S
5、ieve 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,associated with its
6、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-gregatesC128 Test Met
7、hod for Relative Density(Specific Gravity)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.Significance and Use4.1 Specifica
8、tions 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 the laboratory to aconvenient
9、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 this practice could result in prov
10、idinga 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.Substantialdifferences between the selected test sa
11、mples 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 the test sample is being examined for
12、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 importantly influence interpretation of the char
13、ac-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 mechanical splitter according to MethodA.Reduce the
14、 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.1This practice is under the jurisdiction of ASTM Committee C09 on Concreteand ConcreteAggregatesand is the direct responsibility of Subcom
15、mittee C09.20 onNormal Weight Aggregates.Current edition approved Aug.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 Custom
16、er Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.Copyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United States1 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 us