ASTM C133-97(2021)
(Test Method)Standard Test Methods for Cold Crushing Strength and Modulus of Rupture of Refractories
Standard Test Methods for Cold Crushing Strength and Modulus of Rupture of Refractories
SIGNIFICANCE AND USE
3.1 The cold strength of a refractory material is an indication of its suitability for use in refractory construction. (It is not a measure of performance at elevated temperatures.)
3.2 These test methods are for determining the room temperature flexural strength in three-point bending (cold modulus of rupture) or compressive strength (cold crushing strength), or both, for all refractory products.
3.3 Considerable care must be used to compare the results of different determinations of the cold crushing strength or modulus of rupture. The specimen size and shape, the nature of the specimen faces (that is, as-formed, sawed, or ground), the orientation of those faces during testing, the loading geometry, and the rate of load application may all significantly affect the numerical results obtained. Comparisons of the results between different determinations should not be made if one or more of these parameters differ between the two determinations.
3.4 The relative ratio of the largest grain size to the smallest specimen dimension may significantly affect the numerical results. For example, smaller cut specimens containing large grains may present different results than the bricks from which they were cut. Under no circumstances should 6 by 1 by 1-in. (152 by 25 by 25-mm) specimens be prepared and tested for materials containing grains with a maximum grain dimension exceeding 0.25 in. (6.4 mm).
3.5 This test method is useful for research and development, engineering application and design, manufacturing process control, and for developing purchasing specifications.
SCOPE
1.1 These test methods cover the determination of the cold crushing strength and the modulus of rupture (MOR) of dried or fired refractory shapes of all types.
1.2 The test methods appear in the following sections:
Test Method
Sections
Cold Crushing Strength
4 to 9
Modulus of Rupture
10 to 15
1.3 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.
1.4 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.
General Information
Relations
Buy Standard
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: C133 − 97 (Reapproved 2021)
Standard Test Methods for
Cold Crushing Strength and Modulus of Rupture of
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 3. Significance and Use
1.1 These test methods cover the determination of the cold
3.1 The cold strength of a refractory material is an indica-
crushing strength and the modulus of rupture (MOR) of dried
tionofitssuitabilityforuseinrefractoryconstruction.(Itisnot
or fired refractory shapes of all types.
a measure of performance at elevated temperatures.)
1.2 The test methods appear in the following sections:
3.2 These test methods are for determining the room tem-
Test Method Sections
perature flexural strength in three-point bending (cold modulus
of rupture) or compressive strength (cold crushing strength), or
Cold Crushing Strength 4 to 9
both, for all refractory products.
Modulus of Rupture 10 to 15
1.3 The values stated in inch-pound units are to be regarded
3.3 Considerable care must be used to compare the results
as standard. The values given in parentheses are mathematical
of different determinations of the cold crushing strength or
conversions to SI units that are provided for information only
modulus of rupture.The specimen size and shape, the nature of
and are not considered standard.
the specimen faces (that is, as-formed, sawed, or ground), the
orientation of those faces during testing, the loading geometry,
1.4 This standard does not purport to address all of the
and the rate of load application may all significantly affect the
safety concerns, if any, associated with its use. It is the
numericalresultsobtained.Comparisonsoftheresultsbetween
responsibility of the user of this standard to establish appro-
different determinations should not be made if one or more of
priate safety, health, and environmental practices and deter-
these parameters differ between the two determinations.
mine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accor-
3.4 The relative ratio of the largest grain size to the smallest
dance with internationally recognized principles on standard-
specimen dimension may significantly affect the numerical
ization established in the Decision on Principles for the
results. For example, smaller cut specimens containing large
Development of International Standards, Guides and Recom-
grains may present different results than the bricks from which
mendations issued by the World Trade Organization Technical
they were cut. Under no circumstances should 6 by 1 by 1-in.
Barriers to Trade (TBT) Committee.
(152 by 25 by 25-mm) specimens be prepared and tested for
materials containing grains with a maximum grain dimension
2. Referenced Documents
exceeding 0.25 in. (6.4 mm).
2.1 ASTM Standards:
3.5 Thistestmethodisusefulforresearchanddevelopment,
C862 Practice for Preparing Refractory Concrete Specimens
engineering application and design, manufacturing process
by Casting
control, and for developing purchasing specifications.
C1054 Practice for Pressing and Drying Refractory Plastic
and Ramming Mix Specimens
COLD CRUSHING STRENGTH
E4 Practices for Force Verification of Testing Machines
4. Apparatus
These test methods are under the jurisdiction of ASTM Committee C08 on
4.1 Testing Machine—Any form of standard mechanical or
Refractories and are the direct responsibility of Subcommittee C08.01 on Strength.
hydraulic compression testing machine conforming to the
Current edition approved Feb. 1, 2021. Published February 2021. Originally
requirements of Practices E4 may be used.
approved in 1937. Last previous edition approved in 2015 as C133 – 97 (2015).
DOI: 10.1520/C0133-97R21.
NOTE 1—For low-strength materials (such as insulating bricks or
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
castables), a sensitivity of 20 lbf (67 kN) or less is required. The use of a
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 hydraulic testing machine is also preferred over the mechanical type for
the ASTM website. these materials.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C133 − 97 (2021)
4.2 Spherical Bearing Block—The plane surface of the cool to the touch. Complete testing within2hof removal from
spherical bearing block (see Fig. 1) shall have an area which is the drying oven. (See Practices C862 and C1054.)
equal to or greater than the cross section of the test specimen.
6. Procedure
5. Test Specimens
6.1 At least five specimens from an equivalent number of
5.1 Brick and Shapes (bulk density greater than 100 lb/ft
refractory shapes compose a sample.
(1.60 g/cm ))—The test specimens shall be 2-in. (51-mm)
NOTE 2—For relatively weak specimens like insulating castables or
cubes or cylinders, 2 in. (51 mm) in diameter by 2 in. (51 mm)
insulating firebricks, a minimum sample size of ten specimens is pre-
high. The height should be parallel to the original direction of
ferred.
pressing of the brick or shape. In the case of special shapes,
6.2 Brick and Shapes—Place a cellulose fiber wall board
only one specimen shall be cut from a single shape and as
(for example, Masonite ) 0.25 in. (6.4 mm) in thickness and
many of the original surfaces as possible shall be preserved. In
extending 0.5 in. (12.7 mm) or more beyond the edges of the
preparing specimens from irregular or large refractory shapes,
loaded faces of the specimen. Apply the load parallel to the
any method involving the use of abrasives, such as a high-
direction in which the brick was originally pressed.
speed abrasion wheel, core drill, or rubbing bed, that will
produce a specimen with approximately plane and parallel
6.3 RegularandHigh-StrengthCastables—Placeacellulose
sides without weakening the structure of the specimen may be
fiber wall board 0.25 in. (6.4 mm) in thickness and extending
used.
0.5 in. (12.7 mm) or more beyond the edges of the loaded faces
5.2 Insulating Brick or Shapes (typical bulk density of 100 of the specimen. Apply the load on the 2 by 2-in. (51 by
3 3
lb/ft (1.60 g/cm ), or greater than 45% total porosity, or 51-mm) or 2-in. (51-mm) diameter face and perpendicular to
1 1 1
both)—The test specimens shall be 4 ⁄2 by 4 ⁄2 by 2 ⁄2 or 3 in. the depth of the specimen as originally cast or gunned.
(114by114by64or76mm),eachtakenfromadifferentbrick.
6.4 Insulating Brick or Shapes—Apply the load directly to
It is permissible to prepare these specimens from the half-brick
1 1
the 4 ⁄2 by 4 ⁄2-in. (114 by 114-mm) surface of the test
resulting from the modulus of rupture test (see Sections9–
specimen.
14). The selected compression test section shall be free of
cracks, chipped surfaces, and other obvious defects. The test 6.5 Insulating Castables (typical bulk density of 100 lb/ft
(1.60 g/cm ), or greater than 45% total porosity, or both)—
surfaces shall be approximately parallel planes.
Apply the load directly to the 2 by 2-in. (51 by 51-mm) face
5.3 CastableRefractories—The test specimens shall be 2 by
and perpendicular to the depth of the specimen as originally
2 by 2-in. (51 by 51 by 51-mm) cubes or cylinders 2 in.
cast or gunned.
(51 mm) in diameter by 2 in. (51 mm) high, prepared by
casting or gunning. It is permissible to prepare one specimen 6.6 Use the bearing block on top of the test specimen, and
from each 9 by 2 by 2-in. (230 by 51 by 51-mm) bar after the
position it so that the center of the sphere is in alignment with
modulus of rupture test (see Sections9–14). The selected the vertical axis of the specimen (see Fig. 1). Keep the
compression test section shall be free of cracks, chipped
spherical bearing block thoroughly lubricated to ensure accu-
surfaces, and other obvious defects. The loaded surfaces shall rate adjustment which may be made by hand under a small
be approximately parallel planes.All samples must be dried at
initial load for each specimen.
220 to 230 °F (105 to 110 °C) for 18 h (overnight). Upon
NOTE 3—The spherical bearing block may not be necessary on test
removal from the oven, allow the sample to cool naturally until
machines having mechanical linkages which ensure that the stress applied
is colinear with the axis of the specimen.
6.7 For dense refractories with sufficient strength to require
greater than about 3 min per test, initial loading to one half of
the anticipated failure load may be accomplished at any
convenient rate exceeding the specified rate. Subsequently,
each specimen shall be crushed with a compressive load
appliedatthestandardratesspecifiedinTable1.Theratesshall
not vary by more than 610 % of the specified rate for the type
of refractory being tested.
6.8 When using a mechanical testing machine, keep the
balance beam in a constantly floating position.
6.9 Specimens are loaded, as specified, to failure. Failure is
defined as the collapse of the specimen (failure to support the
load), or the reduction of the specimen height to 90 % of its
original value. The maximum applied load is recorded.
FIG. 1 Recommended Design for Crushing Test Assembly,
Including Bearing Block Masonite has been found satisfactory for this purpose.
C133 − 97 (2021)
TABLE 1 Standard Loading Rates for Cold Crushing Strength
Stress Rate,
A
Loaded Cross Loaded Area, in. Loading Rate,
Strain Rate,
Refractory Type Size, in. (mm) lbf/in. /min
in./min (mm/min)
Section, in. (mm) (mm ) lbf/min (kN/min)
(MPa/min)
Refractory Brick and Shapes
3 3 B B B
Density >100 lb/ft (>1.60 gm/cm ), or 2×2×2 2×2 4 1750 7000 0.05
(12) (31.2) (1.3)
<45 % true porosity, or both (51×51×51) (51 × 51) (2601)
B B B
(Includes regular or high-strength castables 2 diameter × 2 2, diameter 3.14 1750 5500 0.05
(12) (24.3) (1.3)
and fired plastic or rammed refractories) (51 diameter × 51) (51, diameter) (2027)
Insulating Refractories
3 3 C,D
Density <100 lb/ft (<1.60 gm/cm ), or 4.5×4.5×2.5 4.5×4.5 20.25 435 8809 0.05
(114×114×64)
>45 % true porosity, or both (114 × 114) (13 064) (3) (39) (1.3)
C,D
(Includes dried, unfired plastic or rammed 4.5×4.5×3 4.5×4.5 20.25 435 8809 0.05
(114×114×76)
refractories) (114 × 114) (13 064) (3) (39) (1.3)
D,E
2×2×2 2×2 4 435 1740 0.05
(51×51×51)
(51 × 51) (2601) (3) (7.80) (1.3)
E
2 diameter × 2 2, diameter 3.14 435 1367 0.05
(51 diameter × 51) (51, diameter) (2027) (3) (6.08) (1.3)
A
Where possible, loading at a constant stress rate is preferable to constant strain rate loading.
B
For dense refractory brick and shapes requiring more than a 3-min test duration, specimens may be loaded to one half of the anticipated fracture strength at any
convenient rate exceeding that specified.
C
These sizes are preferred for insulating firebricks.
D
These pieces may be cut from broken halves of MOR specimens.
E
These sizes are preferred for insulating castables.
7. Calculation 9.2 BearingSurfaces,thatshallhavearadiusofcurvatureof
5 1
⁄8 in. (16 mm) or be cylindrical pieces 1 ⁄4 in. (32 mm) in
7.1 Calculate the cold crushing strength using Eq 1:
diameter.For6by1by1-in.(152by25by25-mm)specimens,
S 5W/A (1)
the radius of curvature shall be ⁄16 in. (5 mm) or cylindrical
pieces ⁄8 in. (10 mm) in diameter. All such bearing surfaces
where:
shall be straight and of a length at least equal to the width of
S = cold crushing strength, lbf/in. (MPa),
the test specimen. The supporting members for the lower
W = total maximum load indicated by the testing machine,
lbf (N), and bearing surfaces shall be constructed so as to provide a means
A = average of the areas of the top and bottom of the forthealignmentofthebearingsurfaceswiththeundersurface
specimen perpendicular to the line of application of the of the test specimen because the test brick may have a
2 2
load, in. (mm ).
longitudinal twist. Apparatus of the design shown in Fig. 2 is
recommended, although other types may be used, provided
8. Report
they conform to these requirements. A satisfactory alternative
design is shown in Fig. 3.
8.1 Report the following:
8.1.1 Designation of the materials tested (that is,
manufacturer, brand, description, lot number, etc.); 10. Test Specimens
8.1.2 Specimen configuration, including size, shape, loca-
10.1 Brick and Shapes (bulk density greater than 100 lb/ft
tion in the original brick or shape, the character of the faces
(1.60 g/cm )—The preferred test specimens shall be standard 9
(that is, cut, drilled, as-pressed, as-cast, etc.), and the specimen
1 1
by 4 ⁄2 by 2 ⁄2 or 3-in. (228 by 114 by 64 or 76-mm) bricks, or
orientation during testing;
specimens of equivalent size ground or cut from refractory
8.1.3 Pretreatment, if any, given to the test pieces (for
shapes. In the case of special shapes, only one specimen shall
example, curing, firing, coking, etc.);
be cut from a single shape. As many original surfaces as
8.1.4 Number of specimens in a sample;
possible shall be preserved. Where brick sizes are impossible
8.1.5 Individual specimen dimensions, the maximum ap-
or impracticable, alternative specimen sizes of 9 by 2 by 2 in.
plied load, and the calculated cold crushing strength for each
(228 by 51 by 51 mm) or 6 by 1 by 1 in. (152 by 25 by 25 mm)
specimen (see 7.1);
may be prepared. In preparing specimens from irregular or
8.1.6 Mean cold crushing strength and standard deviation
larger shapes, any method involving the use of abrasives, such
for each sample.
as a high-speed abrasion wheel or rubbing bed, that will
MODULUS OF RUPTURE produce a specimen with approximately plane and parallel
sides without weakening the structure may be used.
9. Apparatus
10.2 Insulating Brick or Shapes (typical bulk density of 100
9.1 Testing Machine—Any form of standard mechanical or 3 3
lb/ft (1.60 g/cm ), or total porosity greater than 45%, or
hydraulic compression testing machine conforming to the
both)—Thetestspecimensshallbewholebrickmeasuring9by
requirements of Practices E4 may be used.
1 1
4 ⁄2 by 2 ⁄2 or 3 in. (228 by 114 by 64 or 76 mm), or specimens
NOTE 4—Properly calibrated portable apparatus may be used. of equivalent size cut from larger shapes.
...
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: C133 − 97 (Reapproved 2021)
Standard Test Methods for
Cold Crushing Strength and Modulus of Rupture of
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 3. Significance and Use
1.1 These test methods cover the determination of the cold
3.1 The cold strength of a refractory material is an indica-
crushing strength and the modulus of rupture (MOR) of dried
tion of its suitability for use in refractory construction. (It is not
or fired refractory shapes of all types.
a measure of performance at elevated temperatures.)
1.2 The test methods appear in the following sections:
3.2 These test methods are for determining the room tem-
Test Method Sections
perature flexural strength in three-point bending (cold modulus
of rupture) or compressive strength (cold crushing strength), or
Cold Crushing Strength 4 to 9
both, for all refractory products.
Modulus of Rupture 10 to 15
1.3 The values stated in inch-pound units are to be regarded
3.3 Considerable care must be used to compare the results
as standard. The values given in parentheses are mathematical
of different determinations of the cold crushing strength or
conversions to SI units that are provided for information only
modulus of rupture. The specimen size and shape, the nature of
and are not considered standard.
the specimen faces (that is, as-formed, sawed, or ground), the
orientation of those faces during testing, the loading geometry,
1.4 This standard does not purport to address all of the
and the rate of load application may all significantly affect the
safety concerns, if any, associated with its use. It is the
numerical results obtained. Comparisons of the results between
responsibility of the user of this standard to establish appro-
different determinations should not be made if one or more of
priate safety, health, and environmental practices and deter-
these parameters differ between the two determinations.
mine the applicability of regulatory limitations prior to use.
1.5 This international standard was developed in accor-
3.4 The relative ratio of the largest grain size to the smallest
dance with internationally recognized principles on standard-
specimen dimension may significantly affect the numerical
ization established in the Decision on Principles for the
results. For example, smaller cut specimens containing large
Development of International Standards, Guides and Recom-
grains may present different results than the bricks from which
mendations issued by the World Trade Organization Technical
they were cut. Under no circumstances should 6 by 1 by 1-in.
Barriers to Trade (TBT) Committee.
(152 by 25 by 25-mm) specimens be prepared and tested for
materials containing grains with a maximum grain dimension
2. Referenced Documents
exceeding 0.25 in. (6.4 mm).
2.1 ASTM Standards:
3.5 This test method is useful for research and development,
C862 Practice for Preparing Refractory Concrete Specimens
engineering application and design, manufacturing process
by Casting
control, and for developing purchasing specifications.
C1054 Practice for Pressing and Drying Refractory Plastic
and Ramming Mix Specimens
COLD CRUSHING STRENGTH
E4 Practices for Force Verification of Testing Machines
4. Apparatus
These test methods are under the jurisdiction of ASTM Committee C08 on
4.1 Testing Machine—Any form of standard mechanical or
Refractories and are the direct responsibility of Subcommittee C08.01 on Strength.
hydraulic compression testing machine conforming to the
Current edition approved Feb. 1, 2021. Published February 2021. Originally
requirements of Practices E4 may be used.
approved in 1937. Last previous edition approved in 2015 as C133 – 97 (2015).
DOI: 10.1520/C0133-97R21.
NOTE 1—For low-strength materials (such as insulating bricks or
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
castables), a sensitivity of 20 lbf (67 kN) or less is required. The use of a
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
hydraulic testing machine is also preferred over the mechanical type for
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. these materials.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C133 − 97 (2021)
4.2 Spherical Bearing Block—The plane surface of the cool to the touch. Complete testing within 2 h of removal from
spherical bearing block (see Fig. 1) shall have an area which is the drying oven. (See Practices C862 and C1054.)
equal to or greater than the cross section of the test specimen.
6. Procedure
5. Test Specimens
6.1 At least five specimens from an equivalent number of
5.1 Brick and Shapes (bulk density greater than 100 lb/ft
refractory shapes compose a sample.
(1.60 g/cm ))—The test specimens shall be 2-in. (51-mm)
NOTE 2—For relatively weak specimens like insulating castables or
cubes or cylinders, 2 in. (51 mm) in diameter by 2 in. (51 mm)
insulating firebricks, a minimum sample size of ten specimens is pre-
high. The height should be parallel to the original direction of
ferred.
pressing of the brick or shape. In the case of special shapes,
6.2 Brick and Shapes—Place a cellulose fiber wall board
only one specimen shall be cut from a single shape and as
(for example, Masonite ) 0.25 in. (6.4 mm) in thickness and
many of the original surfaces as possible shall be preserved. In
extending 0.5 in. (12.7 mm) or more beyond the edges of the
preparing specimens from irregular or large refractory shapes,
loaded faces of the specimen. Apply the load parallel to the
any method involving the use of abrasives, such as a high-
direction in which the brick was originally pressed.
speed abrasion wheel, core drill, or rubbing bed, that will
produce a specimen with approximately plane and parallel
6.3 Regular and High-Strength Castables—Place a cellulose
sides without weakening the structure of the specimen may be
fiber wall board 0.25 in. (6.4 mm) in thickness and extending
used.
0.5 in. (12.7 mm) or more beyond the edges of the loaded faces
5.2 Insulating Brick or Shapes (typical bulk density of 100
of the specimen. Apply the load on the 2 by 2-in. (51 by
3 3
lb/ft (1.60 g/cm ), or greater than 45 % total porosity, or 51-mm) or 2-in. (51-mm) diameter face and perpendicular to
1 1 1
both)—The test specimens shall be 4 ⁄2 by 4 ⁄2 by 2 ⁄2 or 3 in. the depth of the specimen as originally cast or gunned.
(114 by 114 by 64 or 76 mm), each taken from a different brick.
6.4 Insulating Brick or Shapes—Apply the load directly to
It is permissible to prepare these specimens from the half-brick
1 1
the 4 ⁄2 by 4 ⁄2-in. (114 by 114-mm) surface of the test
resulting from the modulus of rupture test (see Sections 9 –
specimen.
14). The selected compression test section shall be free of
6.5 Insulating Castables (typical bulk density of 100 lb/ft
cracks, chipped surfaces, and other obvious defects. The test
(1.60 g/cm ), or greater than 45 % total porosity, or both)—
surfaces shall be approximately parallel planes.
Apply the load directly to the 2 by 2-in. (51 by 51-mm) face
5.3 Castable Refractories—The test specimens shall be 2 by
and perpendicular to the depth of the specimen as originally
2 by 2-in. (51 by 51 by 51-mm) cubes or cylinders 2 in.
cast or gunned.
(51 mm) in diameter by 2 in. (51 mm) high, prepared by
casting or gunning. It is permissible to prepare one specimen
6.6 Use the bearing block on top of the test specimen, and
from each 9 by 2 by 2-in. (230 by 51 by 51-mm) bar after the position it so that the center of the sphere is in alignment with
modulus of rupture test (see Sections 9 – 14). The selected
the vertical axis of the specimen (see Fig. 1). Keep the
compression test section shall be free of cracks, chipped spherical bearing block thoroughly lubricated to ensure accu-
surfaces, and other obvious defects. The loaded surfaces shall
rate adjustment which may be made by hand under a small
be approximately parallel planes. All samples must be dried at initial load for each specimen.
220 to 230 °F (105 to 110 °C) for 18 h (overnight). Upon
NOTE 3—The spherical bearing block may not be necessary on test
removal from the oven, allow the sample to cool naturally until
machines having mechanical linkages which ensure that the stress applied
is colinear with the axis of the specimen.
6.7 For dense refractories with sufficient strength to require
greater than about 3 min per test, initial loading to one half of
the anticipated failure load may be accomplished at any
convenient rate exceeding the specified rate. Subsequently,
each specimen shall be crushed with a compressive load
applied at the standard rates specified in Table 1. The rates shall
not vary by more than 610 % of the specified rate for the type
of refractory being tested.
6.8 When using a mechanical testing machine, keep the
balance beam in a constantly floating position.
6.9 Specimens are loaded, as specified, to failure. Failure is
defined as the collapse of the specimen (failure to support the
load), or the reduction of the specimen height to 90 % of its
original value. The maximum applied load is recorded.
FIG. 1 Recommended Design for Crushing Test Assembly,
Including Bearing Block Masonite has been found satisfactory for this purpose.
C133 − 97 (2021)
TABLE 1 Standard Loading Rates for Cold Crushing Strength
Stress Rate,
A
Loaded Cross Loaded Area, in. Loading Rate, Strain Rate,
Refractory Type Size, in. (mm) lbf/in. /min
in./min (mm/min)
Section, in. (mm) (mm ) lbf/min (kN/min)
(MPa/min)
Refractory Brick and Shapes
3 3 B B B
Density >100 lb/ft (>1.60 gm/cm ), or 2 × 2 × 2 2 × 2 4 1750 7000 0.05
(12) (31.2) (1.3)
<45 % true porosity, or both (51 × 51 × 51) (51 × 51) (2601)
B B B
(Includes regular or high-strength castables 2 diameter × 2 2, diameter 3.14 1750 5500 0.05
(12) (24.3) (1.3)
and fired plastic or rammed refractories) (51 diameter × 51) (51, diameter) (2027)
Insulating Refractories
3 3 C,D
Density <100 lb/ft (<1.60 gm/cm ), or 4.5 × 4.5 × 2.5 4.5 × 4.5 20.25 435 8809 0.05
(114 × 114 × 64)
>45 % true porosity, or both (114 × 114) (13 064) (3) (39) (1.3)
C,D
(Includes dried, unfired plastic or rammed 4.5 × 4.5 × 3 4.5 × 4.5 20.25 435 8809 0.05
(114 × 114 × 76)
refractories) (114 × 114) (13 064) (3) (39) (1.3)
D,E
2 × 2 × 2 2 × 2 4 435 1740 0.05
(51 × 51 × 51)
(51 × 51) (2601) (3) (7.80) (1.3)
E
2 diameter × 2 2, diameter 3.14 435 1367 0.05
(51 diameter × 51) (51, diameter) (2027) (3) (6.08) (1.3)
A
Where possible, loading at a constant stress rate is preferable to constant strain rate loading.
B
For dense refractory brick and shapes requiring more than a 3-min test duration, specimens may be loaded to one half of the anticipated fracture strength at any
convenient rate exceeding that specified.
C
These sizes are preferred for insulating firebricks.
D
These pieces may be cut from broken halves of MOR specimens.
E
These sizes are preferred for insulating castables.
7. Calculation 9.2 Bearing Surfaces, that shall have a radius of curvature of
5 1
⁄8 in. (16 mm) or be cylindrical pieces 1 ⁄4 in. (32 mm) in
7.1 Calculate the cold crushing strength using Eq 1:
diameter. For 6 by 1 by 1-in. (152 by 25 by 25-mm) specimens,
S 5 W/A (1)
the radius of curvature shall be ⁄16 in. (5 mm) or cylindrical
where: pieces ⁄8 in. (10 mm) in diameter. All such bearing surfaces
shall be straight and of a length at least equal to the width of
S = cold crushing strength, lbf/in. (MPa),
the test specimen. The supporting members for the lower
W = total maximum load indicated by the testing machine,
bearing surfaces shall be constructed so as to provide a means
lbf (N), and
A = average of the areas of the top and bottom of the for the alignment of the bearing surfaces with the under surface
specimen perpendicular to the line of application of the
of the test specimen because the test brick may have a
2 2
load, in. (mm ). longitudinal twist. Apparatus of the design shown in Fig. 2 is
recommended, although other types may be used, provided
8. Report
they conform to these requirements. A satisfactory alternative
design is shown in Fig. 3.
8.1 Report the following:
8.1.1 Designation of the materials tested (that is,
10. Test Specimens
manufacturer, brand, description, lot number, etc.);
8.1.2 Specimen configuration, including size, shape, loca-
10.1 Brick and Shapes (bulk density greater than 100 lb/ft
tion in the original brick or shape, the character of the faces
(1.60 g/cm )—The preferred test specimens shall be standard 9
(that is, cut, drilled, as-pressed, as-cast, etc.), and the specimen
1 1
by 4 ⁄2 by 2 ⁄2 or 3-in. (228 by 114 by 64 or 76-mm) bricks, or
orientation during testing;
specimens of equivalent size ground or cut from refractory
8.1.3 Pretreatment, if any, given to the test pieces (for
shapes. In the case of special shapes, only one specimen shall
example, curing, firing, coking, etc.);
be cut from a single shape. As many original surfaces as
8.1.4 Number of specimens in a sample;
possible shall be preserved. Where brick sizes are impossible
8.1.5 Individual specimen dimensions, the maximum ap-
or impracticable, alternative specimen sizes of 9 by 2 by 2 in.
plied load, and the calculated cold crushing strength for each
(228 by 51 by 51 mm) or 6 by 1 by 1 in. (152 by 25 by 25 mm)
specimen (see 7.1);
may be prepared. In preparing specimens from irregular or
8.1.6 Mean cold crushing strength and standard deviation
larger shapes, any method involving the use of abrasives, such
for each sample.
as a high-speed abrasion wheel or rubbing bed, that will
MODULUS OF RUPTURE
produce a specimen with approximately plane and parallel
sides without weakening the structure may be used.
9. Apparatus
10.2 Insulating Brick or Shapes (typical bulk density of 100
9.1 Testing Machine—Any form of standard mechanical or 3 3
lb/ft (1.60 g/cm ), or total porosity greater than 45 %, or
hydraulic compression testing machine conforming to the
both)—The test specimens shall be whole brick measuring 9 by
requirements of Practices E4 may be used.
1 1
4 ⁄2 by 2 ⁄2 or 3 in. (228 by 114 by 64 or 76 mm), or specimens
NOTE 4—Properly calibrated portable apparatus may be used. of equivalent size cut from larger shapes.
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...
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: C133 − 97 (Reapproved 2015) C133 − 97 (Reapproved 2021)
Standard Test Methods for
Cold Crushing Strength and Modulus of Rupture of
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
1.1 These test methods cover the determination of the cold crushing strength and the modulus of rupture (MOR) of dried or fired
refractory shapes of all types.
1.2 The test methods appear in the following sections:
Test Method Sections
Cold Crushing Strength 4 to 9
Modulus of Rupture 10 to 15
1.3 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.
1.4 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 safety, health, and healthenvironmental 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:
C862 Practice for Preparing Refractory Concrete Specimens by Casting
C1054 Practice for Pressing and Drying Refractory Plastic and Ramming Mix Specimens
E4 Practices for Force Verification of Testing Machines
3. Significance and Use
3.1 The cold strength of a refractory material is an indication of its suitability for use in refractory construction. (It is not a measure
of performance at elevated temperatures.)
These test methods are under the jurisdiction of ASTM Committee C08 on Refractories and are the direct responsibility of Subcommittee C08.01 on Strength.
Current edition approved March 1, 2015Feb. 1, 2021. Published May 2015February 2021. Originally approved in 1937. Last previous edition approved in 20082015 as
ε1
C133 – 97 (2008)(2015). . DOI: 10.1520/C0133-97R15.10.1520/C0133-97R21.
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.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
C133 − 97 (2021)
3.2 These test methods are for determining the room temperature flexural strength in 3-pointthree-point bending (cold modulus
of rupture) or compressive strength (cold crushing strength), or both, for all refractory products.
3.3 Considerable care must be used to compare the results of different determinations of the cold crushing strength or modulus
of rupture. The specimen size and shape, the nature of the specimen faces (that is, as-formed, sawed, or ground), the orientation
of those faces during testing, the loading geometry, and the rate of load application,application may all significantly affect the
numerical results obtained. Comparisons of the results between different determinations should not be made if one or more of these
parameters differ between the two determinations.
3.4 The relative ratio of the largest grain size to the smallest specimen dimension may significantly affect the numerical results.
For example, smaller,smaller cut specimens containing large grains may present different results than the bricks from which they
were cut. Under no circumstances should 6-6 by 1-1 by 1-in. (152-(152 by 25-25 by 25-mm) specimens be prepared and tested
for materials containing grains with a maximum grain dimension exceeding 0.25 in. (6.4 mm).
3.5 This test method is useful for research and development, engineering application and design, manufacturing process control,
and for developing purchasing specifications.
COLD CRUSHING STRENGTH
4. Apparatus
4.1 Testing Machine—Any form of standard mechanical or hydraulic compression testing machine conforming to the requirements
of Practices E4 may be used.
NOTE 1—For low-strength materials (such as insulating bricks or castables), a sensitivity of 20 lbf (67 kN) or less is required. The use of a hydraulic testing
machine is also preferred over the mechanical type for these materials.
4.2 Spherical Bearing Block—The plane surface of the spherical bearing block (see Fig. 1) shall have an area which is equal to
or greater than the cross section of the test specimen.
5. Test Specimens
3 3
5.1 Brick and Shapes (bulk density greater than 100 lb/ft (1.60 g/cm ))—The test specimens shall be 2-in. (51-mm) cubes or
cylinders, 2 in. (51 mm) in diameter by 2 in. (51 mm) high. The height should be parallel to the original direction of pressing of
the brick or shape. In the case of special shapes, only one specimen shall be cut from a single shape and as many of the original
surfaces as possible shall be preserved. In preparing specimens from irregular or large refractory shapes, any method involving the
FIG. 1 Recommended Design for Crushing Test Assembly,
Including Bearing Block
C133 − 97 (2021)
use of abrasives, such as a high-speed abrasion wheel, core drill, or rubbing bed, that will produce a specimen with approximately
plane and parallel sides without weakening the structure of the specimen may be used.
3 3
5.2 Insulating Brick or Shapes (typical bulk density of 100 lb/ft (1.60 g/cm ), or greater than 45 % total porosity, or both)—The
1 1 1
test specimens shall be 4 ⁄2 by 4 ⁄2 by 2 ⁄2 or 3 in. (114 by 114 by 64 or 76 mm), each taken from a different brick. It is permissible
to prepare these specimens from the half-brick resulting from the modulus of rupture test (see Sections 9 – 14). The selected
compression test section shall be free of cracks, chipped surfaces, and other obvious defects. The test surfaces shall be
approximately parallel planes.
5.3 Castable Refractories—The test specimens shall be 2-2 by 2-2 by 2-in. (51-(51 by 51-51 by 51-mm) cubes or cylinders 2 in.
(51 mm) (51 mm) in diameter by 2 in. (51 mm) high, prepared by casting or gunning. It is permissible to prepare one specimen
from each 9-9 by 2-2 by 2-in. (230-(230 by 51-51 by 51-mm) bar after the modulus of rupture test (see Sections 9 – 14). The
selected compression test section shall be free of cracks, chipped surfaces, and other obvious defects. The loaded surfaces shall
be approximately parallel planes. All samples must be dried at 220 to 230°F230 °F (105 to 110°C)110 °C) for 18 h (overnight).
Upon removal from the oven, allow the sample to cool naturally until cool to the touch. Complete testing within 2 h of removal
from the drying oven. (See Practices C862 and C1054.)
6. Procedure
6.1 At least five specimens from an equivalent number of refractory shapes compose a sample.
NOTE 2—For relatively weak specimens like insulating castables or insulating firebricks, a minimum sample size of ten specimens is preferred.
6.2 Brick and Shapes—Place a cellulose fiber wall board (for example, Masonite ) 0.25 in. (6.4 mm) in thickness and extending
0.5 in. (12.7 mm) or more beyond the edges of the loaded faces of the specimen. Apply the load parallel to the direction in which
the brick was originally pressed.
6.3 Regular and High Strength High-Strength Castables—Place a cellulose fiber wall board 0.25 in. (6.4 mm) in thickness and
extending 0.5 in. (12.7 mm) or more beyond the edges of the loaded faces of the specimen. Apply the load on the 2-2 by 2-in.
(51-(51 by 51-mm) or 2-in. (51-mm) diameter face and perpendicular to the depth of the specimen as originally cast or gunned.
1 1
6.4 Insulating Brick or Shapes—Apply the load directly to the 4 ⁄2- by 4 ⁄2-in. (114-(114 by 114-mm) surface of the test specimen.
3 3
6.5 Insulating Castables (typical bulk density of 100 lb/ft (1.60 g/cm ), or greater than 45 % total porosity, or both)—Apply the
load directly to the 2-2 by 2-in. (51-(51 by 51-mm) face and perpendicular to the depth of the specimen as originally cast or
gunned.
6.6 Use the bearing block on top of the test specimen, and position it so that the center of the sphere is in alignment with the
vertical axis of the specimen (see Fig. 1). Keep the spherical bearing block thoroughly lubricated to ensure accurate adjustment
which may be made by hand under a small initial load for each specimen.
NOTE 3—The spherical bearing block may not be necessary on test machines having mechanical linkages which ensure that the stress applied is colinear
with the axis of the specimen.
6.7 For dense refractories with sufficient strength to require greater than about 3 min per test, initial loading to one-half one half
of the anticipated failure load may be accomplished at any convenient rate exceeding the specified rate. Subsequently, each
specimen shall be crushed with a compressive load applied at the standard rates specified in Table 1. The rates shall not vary by
more than 610 % of the specified rate for the type of refractory being tested.
6.8 When using a mechanical testing machine, keep the balance beam in a constantly floating position.
6.9 Specimens are loaded, as specified, to failure. Failure is defined as the collapse of the specimen (failure to support the load),
or the reduction of the specimen height to 90 % of its original value. The maximum applied load is recorded.
Masonite has been found satisfactory for this purpose.
C133 − 97 (2021)
TABLE 1 Standard Loading Rates for Cold Crushing Strength
Stress Rate,
A
Loaded Cross Loaded Area, in. Loading Rate,
Strain Rate,
Refractory Type Size, in. (mm) lbf/in. /min
in./min (mm/min)
Section, in. (mm) mm(mm ) lbf/min (kN/min)
(MPa/min)
Refractory Brick and Shapes
3 3 B B B
Density >100 lb/ft (>1.60 gm/cm ), or 2 × 2 × 2 2 × 2 4 1750 7000 0.05
(12) (31.2) (1.3)
<45 % true porosity, or both (51 × 51 × 51) (51 × 51) (2601)
B B B
(Includes regular or high strength castables 2 diameter × 2 2, diameter 3.14 1750 5500 0.05
(12) (24.3) (1.3)
and fired plastic or rammed refractories) (51 diameter × 51) (51, diameter) (2027)
B B B
(Includes regular or high-strength castables 2 diameter × 2 2, diameter 3.14 1750 5500 0.05
(12) (24.3) (1.3)
and fired plastic or rammed refractories) (51 diameter × 51) (51, diameter) (2027)
Insulating Refractories
3 3 C,D
Density <100 lb/ft (<1.60 gm/cm ), or 4.5 × 4.5 × 2.5 4.5 × 4.5 20.25 435 8809 0.05
(114 × 114 × 64)
>45 % true porosity, or both (114 × 114) (13 064) (3) (39) (1.3)
C,D
(Includes dried, unfired plastic or rammed 4.5 × 4.5 × 3 4.5 × 4.5 20.25 435 8809 0.05
(114 × 114 × 76)
refractories) (114 × 114) (13 064) (3) (39) (1.3)
D,E
2 × 2 × 2 2 × 2 4 435 1740 0.05
(51 × 51 × 51)
(51 × 51) (2601) (3) (7.80) (1.3)
E
2 diameter × 2 2, diameter 3.14 435 1367 0.05
(51 diameter × 51) (51, diameter) (2027) (3) (6.08) (1.3)
A
Where possible, loading at a constant stress rate is preferable to constant strain rate loading.
B
For dense refractory brick and shapes requiring more than a 3-min test duration, specimens may be loaded to one half of the anticipated fracture strength at any
convenient rate exceeding that specified.
C
These sizes are preferred for insulating firebricks.
D
These pieces may be cut from broken halves of MOR specimens.
E
These sizes are preferred for insulating castables.
7. Calculation
7.1 Calculate the cold crushing strength using Eq 1:
S 5 W/A (1)
where:
S = cold crushing strength, lbf/in. (MPa),
W = total maximum load indicated by the testing machine, lbf (N), and
2 2
A = average of the areas of the top and bottom of the specimen perpendicular to the line of application of the load, in. (mm ).
8. Report
8.1 Report the following:
8.1.1 Designation of the materials tested (that is, manufacturer, brand, description, lot number, etc.);
8.1.2 Specimen configuration, including size, shape, location in the original brick or shape, the character of the faces (that is, cut,
drilled, as-pressed, as-cast, etc.), and the specimen orientation during testing;
8.1.3 Pretreatment, if any, given to the test pieces (for example, curing, firing, coking, etc.);
8.1.4 Number of specimens in a sample;
8.1.5 Individual specimen dimensions, the maximum applied load, and the calculated cold crushing strength for each specimen
(see 7.1);
8.1.6 Mean cold crushing strength and standard deviation for each sample.
MODULUS OF RUPTURE
9. Apparatus
9.1 Testing Machine—Any form of standard mechanical or hydraulic compression testing machine conforming to the requirements
of Practices E4 may be used.
C133 − 97 (2021)
NOTE 4—Properly calibrated portable apparatus may be used.
5 1
9.2 Bearing Surfaces, that shall have a radius of curvature of ⁄8 in. (16 mm) or be cylindrical pieces 1 ⁄4-in. (32-mm) in. (32 mm)
in diameter. For 6-6 by 1-1 by 1-in. (152-(152 by 25-25 by 25-mm) specimens, the radius of curvature shall be ⁄16 in. (5 mm) or
cylindrical pieces ⁄8 in. (10 mm) in diameter. All such bearing surfaces shall be straight and of a length at least equal to the width
of the test specimen. The supporting members for the lower bearing surfaces shall be constructed so as to provide a means for the
alignment of the bearing surfaces with the under surface of the test specimen because the test brick may have a longitudinal twist.
Apparatus of the design shown in Fig. 2 is recommended, although other types may be used, provided they conform to these
requirements. A satisfactory alternative design is shown in Fig. 3.
10. Test Specimens
3 3
10.1 Brick and Shapes (bulk density greater than 100 lb/ft (1.60 g/cm )—The preferred test specimens shall be standard 9-9 by
1 1
4 ⁄2- by 2 ⁄2- or 3-in. (228-(228 by 114-114 by 64-64 or 76-mm) bricks, or specimens of equivalent size ground or cut from
refractory shapes. In the case of special shapes, only one specimen shall be
...
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