ASTM C133 - 97(2008)e1

    Standard Test Methods for Cold Crushing Strength and Modulus of Rupture of Refractories

    Active Standard ASTM C133 | Developed by Subcommittee: C08.01

    Book of Standards Volume: 15.01


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    ASTM C133

    Significance and Use

    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 for determining the room temperature flexural strength in 3-point bending (cold modulus of rupture) or compressive strength (cold crushing strength), or both, for all refractory products.

    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.

    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).

    This test method is useful for research and development, engineering application and design, manufacturing process control, and for developing purchasing specifications.

    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 and health practices and determine the applicability of regulatory limitations prior to use.


    2. Referenced Documents (purchase separately) The documents listed below are referenced within the subject standard but are not provided as part of the standard.

    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


    ICS Code

    ICS Number Code 81.080 (Refractories)

    UNSPSC Code

    UNSPSC Code


    DOI: 10.1520/C0133-97R08E01

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