scope:

This test method covers procedures for preparing and testing asphalt concrete mixtures to determine the damage characteristic curve and failure criterion via direct tension cyclic fatigue tests in the Asphalt Mixture Performance Tester (AMPT).

This standard is applicable to laboratory prepared specimens of mixtures with nominal maximum size aggregate less than or equal to 25.0 mm (0.98 in.). Mixtures with a nominal maximum aggregate size greater than or equal to 25.0 mm (0.98 in.) may experience lower success rates.

This standard may involve hazardous material, operations, and equipment. This standard does not purport to address all safety problems associated with its use. It is the responsibility of the user of this procedure to establish appropriate safety and health practices and to determine the applicability of regulatory limitations prior to use.

The quality of the results produced by this standard are dependent on the competence of the personnel performing the procedure and the capability, calibration, and maintenance of the equipment used. Agencies that meet the criteria of R 18 are generally considered capable of competent and objective testing/sampling/inspection/etc. Users of this standard are cautioned that compliance with R 18 alone does not completely assure reliable results. Reliable results depend on many factors; following the suggestions of R 18 or some similar acceptable guideline provides a means of evaluating and controlling some of those factors.