ASTM C1006/C1006M-20a

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Designation: C1006/C1006M − 20 C1006/C1006M − 20a
Standard Test Method for
Splitting Tensile Strength of Masonry Units
This standard is issued under the fixed designation C1006/C1006M; 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.
1. Scope*
1.1 This test method covers the determination of the splitting tensile strength of masonry units.
1.2 Units—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 The text of this standard references notes and footnotes that provide explanatory material. These notes and footnotes
(excluding those in tables and figures) shall not be considered as requirements of the standard.
1.4 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.
1.5 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
2.1 ASTM Standards:
C39/C39M Test Method for Compressive Strength of Cylindrical Concrete Specimens
C1232 Terminology for Masonry
C1552 Practice for Capping Concrete Masonry Units, Related Units and Masonry Prisms for Compression Testing
C1716/C1716M Specification for Compression Testing Machine Requirements for Concrete Masonry Units, Related Units, and
Prisms
3. Terminology
3.1 Definitions:
3.1.1 For definitions of terms used in this test method, refer to Terminology C1232.
3.2 Definitions of Terms Specific to This Standard:
3.2.1 bearing rod, n—steel cylinder to concentrate the applied load along a single line.
This test method is under the jurisdiction of ASTM Committee C15 on Manufactured Masonry Units and is the direct responsibility of Subcommittee C15.04 on Research.
Current edition approved Jan. 1, 2020July 1, 2020. Published January 2020July 2020. Originally approved in 1984. Last previous edition approved in 20192020 as
C1006 – 19.C1006 – 20. DOI: 10.1520/C1006_C1006M-20.10.1520/C1006_C1006M-20A.
For referenced ASTM standards, visit the ASTM website, www.astm.org, or contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM Standards
volume information, refer to the standard’s Document Summary page on the ASTM website.
3.2.1.1 Discussion—
The diameter of the bearing rod is determined by the height of the specimen.
3.2.2 compressible brace, n—tube or rod made of a non-rigid material.
3.2.2.1 Discussion—
*A Summary of Changes section appears at the end of this standard
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C1006/C1006M − 20a
Compressible braces are used to support the test assembly during the initial loading to prevent the rocking of the test assembly.
The compressible braces are required to be the same diameter or slightly smaller in diameter than the bearing rods to prevent
interference with the test results.
3.2.3 gross split length, n—distance along the fracture from one face of the specimen to the opposite face of the specimen.
3.2.4 net split length, n—gross split length minus the length of any voids along the failure plane of the bearing rods.
3.2.5 test assembly, n—the combination of the specimen with a bearing rod adhered to the top and a bearing rod adhered to the
bottom of the specimen.
4. Summary of Test Method
4.1 A test assembly is made by adhering steel bearing rods to the top and bottom faces of the specimen using capping
compound. After the capping compound has cured, the test assembly is placed in the test machine while supported by compressible
braces to prevent the test assembly from rocking. A load is applied to the test assembly. The compressible braces are removed once
the test machine holds the test assembly firmly. The load is continued to be applied until specimen failure.
5. Significance and Use
5.1 Masonry units alone and within assemblages commonly fail in a tensile mode when loaded in compression to failure. These
tensile stresses result from differences in modulus of elasticity and Poisson’s ratio between the masonry unit and mortar.
Additionally, the dissimilarity in behavior of the grout within cores of masonry units under load leads to tensile stresses in the units
and results in a splitting failure.
5.2 This test method produces a line load along the bed surface of the masonry unit. The compressive load applied to the unit,
imposed by means of bearing rods, results in a tensile stress distributed over the height of the unit for the split length of the unit.
This test method can be conducted with the rod oriented either in the longitudinal direction or in the transverse direction of the
bed face. The splitting tensile strength is calculated by the equation given in 10.1.
5.3 The test value provides an indicator of masonry-unit splitting tensile strength. Additionally, the presence of defects such as
visible voids or impurities in masonry units may be revealed.
5.4 The moisture content of the specimen will affect test results.
5.5 The height of the specimen will affect test results.
6. Apparatus
6.1 Bearing Rods—Solid steel bearing rods with diameters 8.0 % to 12.0 % of the specimen height, of a length greater than the
gross split length, and of straightness within 0.5 % of the gross split length shall be provided for each unit. The upper and lower
bearing rods shall have the same diameters. Bearing rods that meet the straightness requirement can be reused.
6.2 Compressible Braces—Non-rigid rods or tubes with a diameter that is 0.0 to 2 mm [0 to ⁄32 in.] smaller than the diameter
of the bearing rods.
6.3 Alignment Jig (for specimens less than 100 mm. [4.0 in.] high)—An alignment jig similar to that shown if Figure 1.
NOTE 1—The alignment jig is used while adhering the rods to the specimen to maintain the two bearing rods in the same vertical plane.
6.4 Supplemental Bearing Bar or Plate—If the diameter or largest dimension of the upper bearing face or lower bearing block
is less than the length of the specimen to be tested, a supplementary bearing bar or plate shall be used. The contact surfaces of
the bar or plate shall be machined to within 0.05 % of planeness as measured on any line of contact of the bearing area. The bearing
bar or plate shall have a width of at least 50 mm [2.0 in.], and a thickness not less than the distance from the edge of the spherical
or rectangular bearing block to the end of the specimen. The bar or plate shall be used in such a manner that the load will be
uniformly applied over the entire gross split length.
6.5 Testing Machine:
6.5.1 The testing machine shall conform to the
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