ASTM C78/C78M-22

Standard Test Method for Flexural Strength of Concrete (Using Simple Beam with Third-Point Loading)

SIGNIFICANCE AND USE
4.1 This test method is used to determine the flexural strength of specimens prepared and cured in accordance with Test Methods C42/C42M or Practices C31/C31M or C192/C192M. Results are calculated and reported as the modulus of rupture. For the same specimen size, the strength determined will vary if there are differences in specimen preparation, curing procedure, moisture condition at time of testing, and whether the beam was molded or sawed to size.  
4.2 The measured modulus of rupture generally increases as the specimen size decreases.3,4,5  
4.3 The results of this test method may be used to determine compliance with specifications or as a basis for mixture proportioning, evaluating uniformity of mixing, and checking placement operations by using sawed beams. It is used primarily in testing concrete for the construction of slabs and pavements.  
4.4 For identical test specimens, the modulus of rupture obtained by this test method will, on average, be lower than that obtained by Test Method C293/C293M.
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.  
1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the two systems may result in non-conformance with the 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, health, and environmental practices and determine the applicability of regulatory limitations prior to use.  
1.4 This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.

General Information

• Status: Published
• Publication Date: 28-Feb-2022
• ICS: 91.100.30 - Concrete and concrete products
• Technical Committee: C09 - Concrete and Concrete Aggregates
• Drafting Committee: C09.61 - Testing for Strength

Standards Content (Sample)

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: C78/C78M − 22
Standard Test Method for
Flexural Strength of Concrete (Using Simple Beam with
1
Third-Point Loading)
This standard is issued under the fixed designation C78/C78M; the number immediately following the designation indicates the year of
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 Defense.
1. Scope* C125 Terminology Relating to Concrete and Concrete Ag-
gregates
1.1 Thistestmethodcoversthedeterminationoftheflexural
C192/C192M Practice for Making and Curing Concrete Test
strength of concrete by the use of a simple beam with
Specimens in the Laboratory
third-point loading.
C293/C293M TestMethodforFlexuralStrengthofConcrete
1.2 The values stated in either SI units or inch-pound units
(Using Simple Beam With Center-Point Loading)
are to be regarded separately as standard. The values stated in
C617/C617M Practice for Capping Cylindrical Concrete
each system may not be exact equivalents; therefore, each
Specimens
system shall be used independently of the other. Combining
C670 Practice for Preparing Precision and Bias Statements
values from the two systems may result in non-conformance
for Test Methods for Construction Materials
with the standard.
E4 Practices for Force Calibration and Verification of Test-
1.3 This standard does not purport to address all of the ing Machines
safety concerns, if any, associated with its use. It is the
E6 Terminology Relating to Methods of Mechanical Testing
responsibility of the user of this standard to establish appro-
3. Terminology
priate safety, health, and environmental practices and deter-
3.1 Definitions:
mine the applicability of regulatory limitations prior to use.
3.1.1 For definitions of terms used in this test method, refer
1.4 This international standard was developed in accor-
to Terminology C125 and Terminology E6.
dance with internationally recognized principles on standard-
3.2 Definitions of Terms Specific to This Standard:
ization established in the Decision on Principles for the
3.2.1 flexural strength—maximum resistance of a speci-
Development of International Standards, Guides and Recom-
men subjected to bending.
mendations issued by the World Trade Organization Technical
Barriers to Trade (TBT) Committee.
3.2.1.1 Discussion—In this test method, flexural strength is
reported as the modulus of rupture.
2. Referenced Documents
3.2.2 flexural testing apparatus—fixture used to apply force
2
2.1 ASTM Standards:
to the beam specimen and consists of loading and support
C31/C31M Practice for Making and Curing Concrete Test
blocks.
Specimens in the Field
3.2.3 loading block—component of the testing apparatus in
C39/C39M Test Method for Compressive Strength of Cylin-
the shape of a portion of a cylinder that is used to apply a force
drical Concrete Specimens
to the beam specimen.
C42/C42M Test Method for Obtaining and Testing Drilled
3.2.4 modulus of rupture—calculated stress, assuming
Cores and Sawed Beams of Concrete
linear-elastic behavior, in the tensile face of a beam specimen
at the maximum bending moment during a standard test
method.
1
This test method is under the jurisdiction of ASTM Committee C09 on
3.2.5 span length—distance between lines of support, or
Concrete and ConcreteAggregates and is the direct responsibility of Subcommittee
C09.61 on Testing for Strength. reaction, for the beam specimen, and it is equal to three times
Current edition approved March 1, 2022. Published March 2022. Originally
the nominal depth of the beam.
approved in 1930. Last previous edition approved in 2021 as C78/C78M – 21. DOI:
10.1520/C0078_C0078M-22.
3.2.5.1 Discussion—For example, for a 100 mm [4 in.]
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
nominaldepthbeam,thespanlengthis300 mm[12 in.]andfor
contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM
a 150 mm [6 in.] nominal depth beam, the span length is
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. 450 mm [18 in.]. See 3.2.6.1, for discussion of reaction block.
*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

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C78/C78M − 22
3.2.6 support block—component of the testing apparatus in 5.1.1.1 The testing machine shall conform to the require-
the shape
...

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/C78M − 21 C78/C78M − 22
Standard Test Method for
Flexural Strength of Concrete (Using Simple Beam with
1
Third-Point Loading)
This standard is issued under the fixed designation C78/C78M; the number immediately following the designation indicates the year of
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 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.
1.2 The values stated in either SI units or inch-pound units are to be regarded separately as standard. The values stated in each
system may not be exact equivalents; therefore, each system shall be used independently of the other. Combining values from the
two systems may result in non-conformance with the 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, health, and environmental practices and determine the applicability of
regulatory limitations prior to use.
1.4 This international standard was developed in accordance with internationally recognized principles on standardization
established in the Decision on Principles for the Development of International Standards, Guides and Recommendations issued
by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
2. Referenced Documents
2
2.1 ASTM Standards:
C31/C31M Practice for Making and Curing Concrete Test Specimens in the Field
C39/C39M Test Method for Compressive Strength of Cylindrical Concrete Specimens
C42/C42M Test Method for Obtaining and Testing Drilled Cores and Sawed Beams of Concrete
C125 Terminology Relating to Concrete and Concrete Aggregates
C192/C192M Practice for Making and Curing Concrete Test Specimens in the Laboratory
C293/C293M Test Method for Flexural Strength of Concrete (Using Simple Beam With Center-Point Loading)
C617/C617M Practice for Capping Cylindrical Concrete Specimens
C670 Practice for Preparing Precision and Bias Statements for Test Methods for Construction Materials
C1077 Practice for Agencies Testing Concrete and Concrete Aggregates for Use in Construction and Criteria for Testing Agency
Evaluation
E4 Practices for Force Calibration and Verification of Testing Machines
E6 Terminology Relating to Methods of Mechanical Testing
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 March 1, 2021March 1, 2022. Published March 2021March 2022. Originally approved in 1930. Last previous edition approved in 20182021 as
C78/C78M – 18.21. DOI: 10.1520/C0078_C0078M-21.10.1520/C0078_C0078M-22.
2
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at [e-mail]. For Annual Book of ASTM 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/C78M − 22
3. Terminology
3.1 Definitions:
3.1.1 For definitions of terms used in this test method, refer to Terminology C125 and Terminology E6.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 flexural strength—maximum resistance of a specimen subjected to bending.
3.2.1.1 Discussion—
In this test method, flexural strength is reported as the modulus of rupture.
3.2.2 flexural testing apparatus—fixture used to apply force to the beam specimen and consists of loading and support blocks.
3.2.3 loading block—component of the testing apparatus in the shape of a portion of a cylinder that is used to apply a force to
the beam specimen.
3.2.4 modulus of rupture—calculated stress, assuming linear-elastic behavior, in the tensile face of a beam specimen at the
maximum bending moment during a standard test method.
3.2.5 span length—distance between lines of support, or reaction, for the beam specimen, and it is equal to three times the
nominal depth of the beam.
3.2.5.1 Discussion—
For exam
...