This test method assigns an empirical value to the relative amount, fineness, and character of clay-like material that may be generated in an aggregate when subjected to mechanical degradation.

The procedure has been used in limited geographical areas of the United States and the results have been correlated with aggregate performance in various construction applications, including: aggregate base, permeable material for backfill, fine concrete aggregate, and riprap for rock slope protection.^{6 ,7}

A minimum durability index is permitted to be specified to prohibit the use of an aggregate in various construction applications that is prone to degradation, resulting in generation of clay-like fines.

This test method provides a rapid test for evaluation of the quality of a new aggregate source. Research has indicated it may also be suitable for use instead of the sodium sulfate soundness test for evaluating the durability characteristics of fine aggregate for use in portland-cement concrete, thereby reducing the need for time-consuming and expensive soundness tests.⁶

Although the application of this method has been limited to aggregates for specific construction uses, the possibility exists for expanding the application of this method to control the quality of aggregates used in other areas of construction, such as aggregates for use in bituminous paving mixtures, coarse aggregate for use in portland-cement concrete, and aggregate for use as railroad ballast.

1.1 This test method covers the determination of a durability index of an aggregate. The calculated durability index is a value indicating the relative resistance of an aggregate to production of detrimental clay-like fines when subjected to the prescribed mechanical methods of degradation.

1.2 The values stated in SI units are to be regarded as the standard. The values given in parentheses are for information only.

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.