scope:

This test method covers the determination of the flexural creep stiffness or compliance of asphalt mixtures by means of a bending beam rheometer. It is applicable to material having a flexural stiffness value from 2 GPa to 20 GPa (creep compliance values in the range of 0.5 nPa^-1 to 0.05 nPa^-1). The test apparatus is designed for testing within the temperature range from -36 to 0°C.

Test results are valid for beams of asphalt mixtures that deflect at least 15 µm and less than 150 µm (550 microstrains) during the entire duration of the test, when tested in accordance with this method.

This method has been verified with asphalt mixtures having a nominal maximum aggregate size of 12.5 mm.

This standard may involve hazardous materials, operations, and equipment. This standard does not purport to address all of the safety concerns 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.