1、Designation:C138/C138M17aAmerican Association StateHighway and Transportation Officials StandardAASHTO No.:T121Standard Test Method forDensity(Unit Weight),Yield,and Air Content(Gravimetric)of Concrete1This standard is issued under the fixed designation C138/C138M;the number immediately following th
2、e designation indicates 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 b
3、y agencies of the U.S.Department of Defense.1.Scope*1.1 This test method covers determination of the density(see Note 1)of freshly mixed concrete and gives formulas forcalculating the yield,cement content,and air content of theconcrete.Yield is defined as the volume of concrete producedfrom a mixtur
4、e of known quantities of the component materi-als.1.2 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 of the other.Combiningvalues from the
5、two systems may result in non-conformancewith the standard.NOTE1Unit weight was the previous terminology used to describe theproperty determined by this test method,which is mass per unit volume.1.3 The text of this test method references notes andfootnotes that provide explanatory information.These
6、 notesand footnotes(excluding those in tables)shall not be consid-ered as requirements of this test method.1.4 This standard 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
7、health practices and determine the applica-bility of regulatory limitations prior to use.(WarningFreshhydraulic cementitious mixtures are caustic and may causechemical burns to skin and tissue upon prolonged exposure.2)1.5 This international standard was developed in accor-dance with internationally
8、 recognized principles on standard-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:3C29/C29M Test Metho
9、d for Bulk Density(“Unit Weight”)and Voids in AggregateC31/C31M Practice for Making and Curing Concrete TestSpecimens in the FieldC143/C143M Test Method for Slump of Hydraulic-CementConcreteC150/C150M Specification for Portland CementC172/C172M Practice for Sampling Freshly Mixed Con-creteC173/C173M
10、 Test Method forAir Content of Freshly MixedConcrete by the Volumetric MethodC188 Test Method for Density of Hydraulic CementC231/C231M Test Method forAir Content of Freshly MixedConcrete by the Pressure MethodC1758/C1758M Practice for Fabricating Test Specimenswith Self-Consolidating Concrete3.Term
11、inology3.1 Symbols:A=air content(percentage of voids)in the concreteC=actual cement content,kg/m3lb/yd3Cb=mass of cement in the batch,kg lbD=density(unit weight)of concrete,kg/m3lb/ft3M=total mass of all materials batched,kg lb(see Note 3)Mc=mass of the measure filled with concrete,kg lb orMm=mass o
12、f the measure,kg lbRy=relative yieldT=theoretical density of the concrete computed on anairfree basis,kg/m3lb/ft3(see Note 2)1This test method is under the jurisdiction of ASTM Committee C09 onConcrete and Concrete Aggregates and is the direct responsibility of SubcommitteeC09.60 on Testing Fresh Co
13、ncrete.Current edition approved March 15,2017.Published May 2017.Originallyapproved in 1938.Last previous edition approved in 2017 as C138/C138M 17.DOI:10.1520/C0138_C0138M-17A.2See section on Safety Precautions,Manual of Aggregate and Concrete Testing,Annual Book of ASTM Standards,Vol 04.02.3For re
14、ferenced 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.*A Summary of Changes section appears at the end of this standardCopyrigh
15、t 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 Stan
16、dards,Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade(TBT)Committee.1 Y=yield,volume of concrete produced per batch,m3yd3Yd=volume of concrete which the batch was designed toproduce,m3yd3Yf=volume of concrete produced per batch,m3ft3V=total absolute volume of the component ingredients inthe batch,m3ft3Vm=volume of the measure,m3ft3NOTE2The theoretical density is,customarily,a laboratorydetermination,the value for which is assumed to remain constant f