The values of IDT strength may be used to evaluate the relative quality of bituminous mixtures in conjunction with laboratory mix design testing and for estimating the potential for rutting or cracking. The results can also be used to determine the potential for field pavement moisture damage when results are obtained on both moisture-conditioned and unconditioned specimens.

1.1 This test method covers procedures for preparing and testing laboratory-fabricated or field-recovered cores of bituminous mixtures to determine the Indirect Tensile (IDT) Strength.

1.2 The within-laboratory repeatability standard deviation, for the recommended rate of loading (50 mm/min) and test temperature (25°C), has been determined to be 80 kPa (12 psi) for 100 mm (4 in.) diameter specimens, based on 28 labs using either 2 or 4 test replicates with 11 different mix samples. Additional data is provided in Table 1 for the users information. The between-laboratory reproducibility of this test method is being determined and will be available on or before August 2011. Therefore, this test method should not be used for acceptance or rejection of materials for purchasing purposes.

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

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.