Stress at failure is used in a mechanistic pavement cracking model to compute critical cracking temperature. The procedure to compute critical cracking temperature is described in Practice D 6521. The critical cracking temperature is then used in specifying the low temperature grade of asphalt binder in accordance with Specification D 6373.

The test method is designed to measure the strength of the asphalt binder at the critical cracking temperature. The asphalt binder has limited ability to resist stress without cracking. In the asphalt binder Specification D 6373, failure stress is used to determine the critical cracking temperature.

For evaluating an asphalt binder for conformance to Specification D 6373, the elongation rate of the gage section is 1.0 mm/min and the test temperature is selected from Table number 1 of Specification D 6373 according to the grade of asphalt binder. Other rates of elongation and test temperatures may be used to test asphalt binders.

1.1 This test method covers the determination of the failure strain and failure stress of asphalt binders by means of a direct tension test. It can be used with unaged material or with material aged using Test Method D 2872 (RTFOT), Practice D 6521 (PAV), or AASHTO T240 (RTFOT) and AASHTO PP1 (PAV). The test apparatus is designed for testing within the temperature range from +6 to -36°C.

1.2 This test method is limited to asphalt binders containing particulate material having dimensions less than 250 μm.

1.3 The values stated in SI units are to be regarded as the 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.