ASTM_C_78_-_C_78M_-_16.pdf

Designation:C78/C78M16Standard Test Method forFlexural Strength of Concrete(Using Simple Beam withThird-Point Loading)1This standard is issued under the fixed designation C78/C78M;the number immediately following the designation indicates the year oforiginal adoption or,in the case of revision,the year of last revision.A number in parentheses indicates the year of last reapproval.Asuperscript 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 Defense.1.Scope*1.1 This test method covers the determination of the flexuralstrength of concrete by the use of a simple beam withthird-point loading.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 two systems may result in non-conformancewith the standard.1.3 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 health practices and determine the applica-bility of regulatory limitations prior to use.2.Referenced Documents2.1 ASTM Standards:2C31/C31M Practice for Making and Curing Concrete TestSpecimens in the FieldC42/C42M Test Method for Obtaining and Testing DrilledCores and Sawed Beams of ConcreteC192/C192M Practice for Making and Curing Concrete TestSpecimens in the LaboratoryC617/C617M Practice for Capping Cylindrical ConcreteSpecimensC1077 Practice for Agencies Testing Concrete and ConcreteAggregates for Use in Construction and Criteria forTesting Agency EvaluationE4 Practices for Force Verification of Testing Machines3.Significance and Use3.1 This test method is used to determine the flexuralstrength of specimens prepared and cured in accordance withTest Methods C42/C42M or Practices C31/C31M or C192/C192M.Results are calculated and reported as the modulus ofrupture.For the same specimen size,the strength determinedwill vary if there are differences in specimen preparation,curing procedure,moisture condition at time of testing,andwhether the beam was molded or sawed to size.3.2 The measured modulus of rupture generally increases asthe specimen size decreases3,4,5and it has been shown that thevariability of individual test results increases as the specimensize decreases.3,43.3 The results of this test method may be used to determinecompliance with specifications or as a basis for mixtureproportioning,evaluating uniformity of mixing,and checkingplacement operations by using sawed beams.It is used primar-ily in testing concrete for the construction of slabs andpavements.4.Apparatus4.1 Testing MachineThe testing machine shall conform tothe requirements of the sections on Basis of Verification,Corrections,and Time Interval Between Verifications of Prac-tices E4.Hand operated testing machines having pumps that donot provide a continuous loading in one stroke are notpermitted.Motorized pumps or hand operated positive dis-placement pumps having sufficient volume in one continuousstroke to complete a test without requiring replenishment are1This test method is under the jurisdiction of ASTM Committee C09 onConcrete and Concrete Aggregates and is the direct responsibility of SubcommitteeC09.61 on Testing for Strength.Current edition approved July 1,2016.Published August 2016.Originallyapproved in 1930.Last previous edition approved in 2015 as C78/C78M 15b.DOI:10.1520/C0078_C0078M-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.3Tanesi,J;Ardani,A.Leavitt,J.Reducing the Specimen Size of ConcreteFlexural Strength Test(AASHTO T97)for Safety and Ease of Handling,Trans-portation Research Record:Journal of the Transportation Research Board,No.2342,Transportation Research Board of National Academies,Washington,D.C.,2013.4Carrasquillo,P.M.and Carrasquillo,R.L“Improved Concrete Quality ControlProcedures Using Third Point Loading”,Research Report 119-1F,Project 3-9-87-1119,Center For Transportation Research,The University of Texas at Austin,November 1987.5Bazant,Z.and Novak,D.Proposal for Standard Test of Modulus of Ruptureof Concrete with its Size Dependence,ACI Materials Journal,January-February2001.*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 States1 permitted and shall be capable of applying loads at a uniformrate without shock or interruption.The testing machine shall beequipped with a means of recording or holding the peak valuethat will indicate the maximum load,to within 1%accuracy,applied to the specimen during a test.4.2 Loading Appara