ASTM C78-09

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:C78–08 Designation:C78–09
Standard Test Method for
Flexural Strength of Concrete (Using Simple Beam with
1
Third-Point Loading)
ThisstandardisissuedunderthefixeddesignationC 78;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoption or, in the case of revision, the year of last revision.Anumber 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 Department of Defense.
1. Scope*
1.1 This test method covers the determination of the flexural strength of concrete by the use of a simple beam with third-point
loading.
1.2The values stated in inch-pound units are to be regarded as the standard. The SI equivalent of inch-pound units has been
rounded where necessary for practical application.
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only and are not considered standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2
2.1 ASTM Standards:
C 31/C 31M Practice for Making and Curing Concrete Test Specimens in the Field
C 42/C 42M Test Method for Obtaining and Testing Drilled Cores and Sawed Beams of Concrete
C 192/C 192M Practice for Making and Curing Concrete Test Specimens in the Laboratory
C 617 Practice for Capping Cylindrical Concrete Specimens
C 1077 PracticeforLaboratoriesTestingConcreteandConcreteAggregatesforUseinConstructionandCriteriaforLaboratory
Evaluation
E4 Practices for Force Verification of Testing Machines
3. Significance and Use
3.1 ThistestmethodisusedtodeterminetheflexuralstrengthofspecimenspreparedandcuredinaccordancewithTestMethods
C 42/C 42M or Practices C 31/C 31M or C 192/C 192M. Results are calculated and reported as the modulus of rupture. The
strength determined will vary where there are differences in specimen size, preparation, moisture condition, curing, or where the
beam has been molded or sawed to size.
3.2 The results of this test method may be used to determine compliance with specifications or as a basis for proportioning,
mixing and placement operations. It is used in testing concrete for the construction of slabs and pavements.
4. Apparatus
4.1 The testing machine shall conform to the requirements of the sections on Basis of Verification, Corrections, and Time
Interval Between Verifications of Practices E 4. Hand operated testing machines having pumps that do not provide a continuous
loading in one stroke are not permitted. Motorized pumps or hand operated positive displacement pumps having sufficient volume
in one continuous stroke to complete a test without requiring replenishment are permitted and shall be capable of applying loads
at a uniform rate without shock or interruption.
4.2 Loading Apparatus—The third point loading method shall be used in making flexure tests of concrete employing bearing
blocks which will ensure that forces applied to the beam will be perpendicular to the face of the specimen and applied without
1
This test method is under the jurisdiction of ASTM Committee C09 on Concrete and Concrete Aggregates and is the direct responsibility of Subcommittee C09.61 on
Testing for Strength.
Current edition approved Feb.July 1, 2008.2009. Published February 2008.August 2009. Originally approved in 1930. Last previous edition approved in 20072008 as
C 78 – 078.
2
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book ofASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1

---------------------- Page: 1 ----------------------
C78–09
eccentricity. A diagram of an apparatus that accomplishes this purpose is shown in Fig. 1.
4.2.1 All apparatus for making flexure tests of concrete shall be capable of maintaining the specified span length and distances
between load-applying blocks and support blocks constant within 60.05 in. (61.3 mm).
4.2.2 The ratio of th
...

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation:C78–08 Designation:C78–09
Standard Test Method for
Flexural Strength of Concrete (Using Simple Beam with
1
Third-Point Loading)
ThisstandardisissuedunderthefixeddesignationC 78;thenumberimmediatelyfollowingthedesignationindicatestheyearoforiginal
adoption or, in the case of revision, the year of last revision.Anumber 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 Department of Defense.
1. Scope*
1.1 This test method covers the determination of the flexural strength of concrete by the use of a simple beam with third-point
loading.
1.2The values stated in inch-pound units are to be regarded as the standard. The SI equivalent of inch-pound units has been
rounded where necessary for practical application.
1.2 The values stated in inch-pound units are to be regarded as standard. The values given in parentheses are mathematical
conversions to SI units that are provided for information only and are not considered standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility
of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory
limitations prior to use.
2. Referenced Documents
2
2.1 ASTM Standards:
C 31/C 31M Practice for Making and Curing Concrete Test Specimens in the Field
C 42/C 42M Test Method for Obtaining and Testing Drilled Cores and Sawed Beams of Concrete
C 192/C 192M Practice for Making and Curing Concrete Test Specimens in the Laboratory
C 617 Practice for Capping Cylindrical Concrete Specimens
C 1077 PracticeforLaboratoriesTestingConcreteandConcreteAggregatesforUseinConstructionandCriteriaforLaboratory
Evaluation
E4 Practices for Force Verification of Testing Machines
3. Significance and Use
3.1 ThistestmethodisusedtodeterminetheflexuralstrengthofspecimenspreparedandcuredinaccordancewithTestMethods
C 42/C 42M or Practices C 31/C 31M or C 192/C 192M. Results are calculated and reported as the modulus of rupture. The
strength determined will vary where there are differences in specimen size, preparation, moisture condition, curing, or where the
beam has been molded or sawed to size.
3.2 The results of this test method may be used to determine compliance with specifications or as a basis for proportioning,
mixing and placement operations. It is used in testing concrete for the construction of slabs and pavements.
4. Apparatus
4.1 The testing machine shall conform to the requirements of the sections on Basis of Verification, Corrections, and Time
Interval Between Verifications of Practices E 4. Hand operated testing machines having pumps that do not provide a continuous
loading in one stroke are not permitted. Motorized pumps or hand operated positive displacement pumps having sufficient volume
in one continuous stroke to complete a test without requiring replenishment are permitted and shall be capable of applying loads
at a uniform rate without shock or interruption.
4.2 Loading Apparatus—The third point loading method shall be used in making flexure tests of concrete employing bearing
blocks which will ensure that forces applied to the beam will be perpendicular to the face of the specimen and applied without
1
This test method is under the jurisdiction of ASTM Committee C09 on Concrete and Concrete Aggregates and is the direct responsibility of Subcommittee C09.61 on
Testing for Strength.
Current edition approved Feb.July 1, 2008.2009. Published February 2008.August 2009. Originally approved in 1930. Last previous edition approved in 20072008 as
C 78 – 078.
2
For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at service@astm.org. For Annual Book ofASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
*A Summary of Changes section appears at the end of this standard.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
1

---------------------- Page: 1 ----------------------
C78–09
eccentricity. A diagram of an apparatus that accomplishes this purpose is shown in Fig. 1.
4.2.1 All apparatus for making flexure tests of concrete shall be capable of maintaining the specified span length and distances
between load-applying blocks and support blocks constant within 60.05 in. (61.3 mm).
4.2.2 The ratio of th
...