1、Designation:C702/C702M18American 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 testing.These techniques are intended to minimize variations inmeasured characteristics between the test samples selected andthe large sample.1.2 The values stated in eit
4、her 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.NOTE1Sieve size is
5、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 use.It is the
6、responsibility of the user of this standard to establish appro-priate safety,health,and environmental practices and deter-mine the applicability of regulatory limitations prior to use.1.4 This international standard was developed in accor-dance with internationally recognized principles on standard-
7、ization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2C125 Terminology Relating to Concrete and Concrete Ag-
8、gregatesC128 Test Method 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
9、 and Use4.1 Specifications for aggregates require obtaining represen-tative portions of the supply material for testing.Other factorsbeing equal,larger samples will tend to be more representativeof the total supply.This practice provides procedures forreducing the large sample obtained in the field,
10、or produced inthe laboratory,to a convenient size for conducting a number ofdescriptive and quality tests.Failure to carefully follow theprocedures in this practice could result in providing a non-representative sample to be used in subsequent testing.Theindividual test methods provide for minimum a
11、mount 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 samples sometimes can-not be avoided,for example,in the case of an aggregate havingrelatively few large size particl
12、es in the sample.The laws ofchance dictate that these few particles may be unequallydistributed among the reduced size test samples.Similarly,ifthe test sample is being examined for certain contaminantsoccurring in only small percentages,caution should be used ininterpreting results from the reduced
13、 size test sample.Chanceinclusion or exclusion of only one or two particles in theselected test sample may importantly influence interpretationof the characteristics of the original sample.In these cases,theentire original sample should be tested.5.Selection of Method5.1 Fine AggregateReduce the siz
14、e of samples of fineaggregate that are drier than the saturated-surface-dry condi-tion(Note 2)using a mechanical splitter according to Method1This practice is under the jurisdiction of ASTM Committee C09 on Concreteand ConcreteAggregates and is the direct responsibility of Subcommittee C09.20 onAggr
15、egates.Current edition approved Feb.1,2018.Published March 2018.Originallyapproved in 1971.Last previous edition approved in 2011 as C702/C702M11.DOI:10.1520/C0702_C0702M-18.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annu
16、al 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 StatesThis international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for theDevelopment of International Standards,Guides and Recommendations issued by the World Trade Organization Technical Ba
