1、Designation:C457/C457M16Standard Test Method forMicroscopical Determination of Parameters of the Air-VoidSystem in Hardened Concrete1This standard is issued under the fixed designation C457/C457M;the number immediately following the designation indicates the yearof original adoption or,in the case o
2、f 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.1.Scope*1.1 This test method describes procedures for microscopicaldeterminations of the air content of harden
3、ed concrete and ofthe specific surface,void frequency,spacing factor,and paste-air ratio of the air-void system in hardened concrete.Threeprocedures are described:1.1.1 Procedure ALinear-traverse method.1.1.2 Procedure BModified point-count method.1.1.3 Procedure CContrast enhanced method.1.2 This t
4、est method is based on prescribed procedures thatare applied to sawed and lapped sections of specimens ofconcrete from the field or laboratory.1.3 It is intended to outline the principles of this test methodand to establish standards for its adequate performance but notto describe in detail all the
5、possible variations that might beused to accomplish the objectives of this test method.1.4 The values 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 o
6、f the other.Combiningvalues from the two systems may result in non-conformancewith the standard.1.5 This standard does not purport to address all of thesafety concerns associated with its use.It is the responsibilityof the user of this standard to establish appropriate safety andhealth practices and
7、 determine the applicability of regulatorylimitations prior to use.For specific hazard statements seeNote 9 and Note 12.1.6 This international standard was developed in accor-dance with internationally recognized principles on standard-ization established in the Decision on Principles for theDevelop
8、ment of International Standards,Guides and Recom-mendations issued by the World Trade Organization TechnicalBarriers to Trade(TBT)Committee.2.Referenced Documents2.1 ASTM Standards:2C42/C42M Test Method for Obtaining and Testing DrilledCores and Sawed Beams of ConcreteC125 Terminology Relating to Co
9、ncrete and Concrete Ag-gregatesC138/C138M Test Method for Density(Unit Weight),Yield,and Air Content(Gravimetric)of ConcreteC173/C173M Test Method forAir Content of Freshly MixedConcrete by the Volumetric MethodC231/C231M Test Method forAir Content of Freshly MixedConcrete by the Pressure MethodC666
10、/C666M Test Method for Resistance of Concrete toRapid Freezing and ThawingC670 Practice for Preparing Precision and Bias Statementsfor Test Methods for Construction MaterialsC672/C672M Test Method for Scaling Resistance of Con-crete Surfaces Exposed to Deicing ChemicalsC823/C823M Practice for Examin
11、ation and Sampling ofHardened Concrete in ConstructionsC856 Practice for Petrographic Examination of HardenedConcreteD92 Test Method for Flash and Fire Points by ClevelandOpen Cup Tester2.2 American Concrete Institute Standards:3201.2R Guide to Durable Concrete211.1 Standard Practice for Selecting P
12、roportions forNormal,Heavyweight,and Mass Concrete3.Terminology3.1 For definitions of terms used in this test method,refer toTerminology C125.3.2 Definitions of Terms Specific to This Standard:3.2.1 average chord lengthl!,nthe average length of thechords formed by the transection of the voids by the
13、 line of1This test method is under the jurisdiction of ASTM Committee C09 onConcrete and Concrete Aggregates and is the direct responsibility of SubcommitteeC09.65 on Petrography.Current edition approved Dec.1,2016.Published April 2017.Originallyapproved in 1960.Last previous edition approved in 201
14、2 as C457/C457M 12.DOI:10.1520/C0457_C0457M-16.2For referenced ASTM standards,visit the ASTM website,www.astm.org,orcontact ASTM Customer Service at serviceastm.org.For Annual Book of ASTMStandards volume information,refer to the standards Document Summary page onthe ASTM website.3Available from Ame
15、rican Concrete Institute(ACI),P.O.Box 9094,FarmingtonHills,MI 48333-9094,http:/www.aci-int.org.*A Summary of Changes section appears at the end of this standardCopyright ASTM International,100 Barr Harbor Drive,PO Box C700,West Conshohocken,PA 19428-2959.United StatesThis international standard was
16、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 Barriers to Trade(TBT)Committee.1 traverse;the unit is a length.3.2.2 binary image,nformed by segmenting an imageusing only one threshold with the resulting image having onlyareas of black or white.3.2.3 digital image,nan image captured using acomput
