Alternate Methods of Asphalt Content Determination

About the report:

This study identified an alternate method of asphalt content determination to replace chlorinated solvent extraction. The production of trichloroethane was outlawed on December 31, 1996, as part of the 1990 Clean Air Act Amendments. Initially, the study focused on evaluating the nuclear asphalt content gauge with Marshall plugs. During the course of the research, early data from the National Center for Asphalt Technology (NCAT) indicated that the ignition method was a promising alternative. Testing was conducted using three generations of ignition furnaces. Four aggregate types were evaluated using typical surface and base mix gradations found in Virginia. Samples for evaluation were produced at four asphalt contents for each mix design representing typical field variation around the optimum. Operator variance samples were tested non-destructively in the nuclear gauge, and then destructively tested by solvent extraction and the ignition method. In the field validation phase, four methods were used for testing. The gradations of these samples are compared. As a result of the research, a test method was developed for the ignition furnace with an internal weighing system. This method has been specified as a replacement for solvent extraction in Virginia.

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