Standard Active Last Updated: Oct 03, 2019
ASTM C689-09(2019)

Standard Test Method for Modulus of Rupture of Unfired Clays

Significance and Use

3.1 The purpose of this test method is to obtain values of rupture modulus of clays before firing, under various processing conditions (relative humidity).


This test method details the standard procedure for the determination of modulus of rupture of ceramic whiteware clays, both dry and after conditioning at specified relative humidity, or both. The apparatuses needed for this method are a conditioning cabinet, and a testing machine. Extruded, clay-flint, and solid cast specimens shall be prepared accordingly. Specific procedures as to handling, warpage, drying, and storage, and the corresponding calculations are discussed thoroughly.


1.1 This test method covers the determination of the modulus of rupture of ceramic whiteware clays both dry and after conditioning at 50 or 80 % relative humidity, or both.

1.2 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.

1.3 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.

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Book of Standards Volume: 15.02
Developed by Subcommittee: C21.04
Pages: 3
DOI: 10.1520/C0689-09R19
ICS Code: 91.100.15