4.1 To determine the characteristics of the asphalt in an asphalt paving mixture, it is necessary to extract the asphalt from the aggregate by means of a suitable solvent and then to recover the asphalt from the solvent without significantly changing the asphalt's properties. The asphalt recovered from the solvent by this practice can be tested using the same methods as for the original asphalt cement, and comparisons between the properties of the original and recovered asphalt can be made.

4.2 Users are cautioned that the recovered binder properties from an asphalt mixture sample may not exactly represent the properties of the original asphalt binder due to factors outside of laboratory control such as aging, contamination, and molecular changes caused by exposure to heat and solvents. Consequently, recovered asphalt binder properties should not be used as a basis for acceptance.

Note 1: The quality of the results produced by this is 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 Specification D3666 are generally considered capable of competent and objective testing, sampling, inspection, and so forth. Users of this practice are cautioned that compliance with Specification D3666 alone does not completely ensure reliable results. Reliable results depend on many factors; following the suggestions of Specification D3666 or some similar acceptable guideline provides a means of evaluating and controlling some of those factors.