The true specific gravity of a material is the ratio of its true density, determined at a specific temperature, to the true density of water, determined at a specific temperature. Thus, the true specific gravity of a material is a primary property which is related to chemical and mineralogical composition.

For refractory raw materials and products the true specific gravity is a useful value for: classification, detecting differences in chemical composition between supposedly like samples, indicating mineralogical phases or phase changes, calculating total porosity when the bulk density is known, and for any other test method which requires this value for the calculation of results.

This test method is a primary standard method which is suitable for use in specifications, quality control, and research and development. It can also serve as a referee test method in purchasing contracts or agreements.

Fundamental assumptions inherent in this test method are the following:

The sample is representative of the material in general,

The total sample has been reduced to the particle size specified,

No impurity has been introduced during processing of the sample,

The sample itself is not magnetic and all magnetic material introduced during processing of the sample has been removed,

The material is not hydratable or reactive with water, and

The test method has been conducted in a meticulous manner.

Deviation from any of these assumptions negates the usefulness of the results.

In interpreting the results of this test method it must be recognized that the specified sample particle size does not guarantee that all closed pores have been eliminated. The amount of residual closed pores may vary between materials or even between samples of the same or like materials, and the specified sample particle size is not the same as that specified for Test Method C 604. The values generated by this test method may, therefore, be close approximations rather than accurate representations of true specific gravities. Thus, comparisons of results should only be judiciously made between like materials tested by this test method or with full recognition of potentially inherent differences between the materials being compared or the test method used.

1.1 This test method covers the determination of true specific gravity of refractory materials under prescribed conditions. It is not applicable to materials attacked by water.

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.

1.2.1 Exception—The equipment used in this standard for weights and volumes is only available in SI units.

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