scope:

This method covers the measurement of the oxidation signal in an asphalt mixture by a portable infrared spectrometer (PIRS) equipped with a diffuse reflectance accessory. Three oxidation signals are compared: (1) the in-place pavement, (2) asphalt mixture production sample, and (3) the approved job mixture formula specimen. The oxidation signals are determined from a specified peak value from the absorbance spectrum of the asphalt samples.

The in-place pavement PIRS oxidation signal can be used to assess its aging rate. The pavement aging rate is determined by comparing its initial PIRS oxidation signal with successive PIRS oxidation signals obtained at some defined frequency.

This standard does not purport to address all the safety concerns 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. See Section 12 for more details.

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.