ASTM C133-24

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: C133 − 24
Standard Test Methods for
Cold Crushing Strength and Modulus of Rupture of
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Refractories
This standard is issued under the fixed designation C133; 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 E4 Practices for Force Calibration and Verification of Test-
ing Machines
1.1 These test methods cover the determination of the cold
crushing strength and the modulus of rupture (MOR) of dried
3. Significance and Use
or fired refractory shapes of all types.
3.1 The cold strength of a refractory material is an indica-
1.2 The test methods appear in the following sections:
tion of its suitability for use in refractory construction. (It is not
Test Method Sections
a measure of performance at elevated temperatures.)
Cold Crushing Strength 4 to 8
3.2 These test methods are for determining the room tem-
Modulus of Rupture 9 to 13
perature flexural strength in three-point bending (cold modulus
1.3 The values stated in inch-pound units are to be regarded
of rupture) or compressive strength (cold crushing strength), or
as standard. The values given in parentheses are mathematical
both, for all refractory products.
conversions to SI units that are provided for information only
3.3 Considerable care must be used to compare the results
and are not considered standard.
of different determinations of the cold crushing strength or
1.4 This standard does not purport to address all of the
modulus of rupture. The specimen size and shape, the nature of
safety concerns, if any, associated with its use. It is the
the specimen faces (that is, as-formed, sawed, or ground), the
responsibility of the user of this standard to establish appro-
orientation of those faces during testing, the loading geometry,
priate safety, health, and environmental practices and deter-
and the rate of load application may all significantly affect the
mine the applicability of regulatory limitations prior to use.
numerical results obtained. Comparisons of the results between
1.5 This international standard was developed in accor-
different determinations should not be made if one or more of
dance with internationally recognized principles on standard-
these parameters differ between the two determinations.
ization established in the Decision on Principles for the
3.4 The relative ratio of the largest grain size to the smallest
Development of International Standards, Guides and Recom-
specimen dimension may significantly affect the numerical
mendations issued by the World Trade Organization Technical
results. For example, smaller cut specimens containing large
Barriers to Trade (TBT) Committee.
grains may present different results than the bricks from which
they were cut. Under no circumstances should 6 in. by 1 in. by
2. Referenced Documents
1 in. (152 mm by 25 mm by 25 mm) specimens be prepared
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2.1 ASTM Standards:
and tested for materials containing grains with a maximum
C862 Practice for Preparing Refractory Concrete Specimens
grain dimension exceeding 0.25 in. (6.4 mm).
by Casting
3.5 This test method is useful for research and development,
C1054 Practice for Pressing and Drying Refractory Plastic
engineering application and design, manufacturing process
and Ramming Mix Specimens
control, and for developing purchasing specifications.
COLD CRUSHING STRENGTH
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These test methods are under the jurisdiction of ASTM Committee C08 on
4. Apparatus
Refractories and are the direct responsibility of Subcommittee C08.01 on Strength.
Current edition approved April 1, 2024. Published April 2024. Originally
4.1 Testing Machine—Any form of standard mechanical or
approved in 1937. Last previous edition approved in 2021 as C133 – 97 (2021).
hydraulic compression testing machine conforming to the
DOI: 10.1520/C0133-24.
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For referenced ASTM standards, visit the ASTM website, www.astm.org, or
requirements of Practices E4 may be used.
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 NOTE 1—For low-strength materials (such as insulating bricks or
the ASTM website. castables), a sensitivity of 20 lbf (67 kN) or less is required. The use of a
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