Microwave apparatus and method for analysis of asphalt-aggregate compositions

A method of analyzing the aggregate content of asphalt-aggregate compositions, the method comprising:

• placing a preheated, preweighed container carrying a sample of an asphalt-aggregate composition into a preheated furnace with the preheated furnace being warmer than the preheated sample;
• continuing to heat the furnace by directing microwave radiation at microwave adsorbent materials in the furnace;
• initiating a first draw of air through the furnace at a rate that avoids impeding the heating of the furnace or the sample until the sample in the container reaches its combustion temperature and the combustion of the sample becomes exothermic;
• initiating a second draw of air around rather than through the furnace to moderate the exterior temperature of the furnace;
• moderating the first draw of air through the furnace to increase the rate of combustion of the exothermic reaction;
• and
• reweighing the container and sample after combustion is complete.

A method of analyzing the aggregate content of asphalt-aggregate compositions, the method comprising:

• placing a preheated, preweighed container carrying a sample of an asphalt-aggregate composition into a preheated furnace;
• monitoring the temperature of the furnace;
• continuing to heat the furnace by directing microwave radiation at microwave adsorbent materials in the furnace;
• initiating a first draw of air through the furnace at a rate that avoids impeding the heating of the furnace or the sample until the sample in the container reaches a first predetermined setpoint temperature;
• initiating a second draw of air around rather than through the furnace to moderate the exterior temperature of the furnace when the temperature reaches a second predetermined setpoint;
• moderating the first draw of air through the furnace to increase the rate of combustion of the sample;
• and
• reweighing the container and sample after combustion is complete.

An apparatus for analyzing the aggregate content of asphalt-aggregate compositions and comprising:

• a cavity for holding an asphalt-aggregate sample;
• means for introducing microwave radiation into said cavity;
• materials in said cavity for absorbing microwave radiation and converting the microwave radiation into heat;
• an afterburner in gas flow communication with said cavity;
• a first controllable variable speed fan for drawing air through said cavity and through said afterburner;
• a second controllable variable speed fan for drawing air around said cavity to moderate the external temperature of said cavity and its immediate environment;
• a temperature sensor in said cavity for monitoring the temperature of the sample;
• a controller that moderates the draw of said first fan based upon the sample temperature measured by said temperature sensor;
• and
• a controller that moderates the draw of said second fan. aggregate after combustion of the asphalt.

An asphalt analysis furnace system that enhances the airflow and combustion of asphalt-aggregate compositions, said furnace system comprising:

• a furnace, that include a source of microwave radiation and a susceptor for absorbing the microwave radiation and converting it into heat;
• a housing around said furnace;
• a furnace exhaust in communication with said furnace;
• a housing exhaust in communication with said housing;
• means for drawing an airflow though said furnace and into said furnace exhaust;
• means for drawing a separate airflow though said housing and into said housing exhaust;
• and
• a junction between said exhausts that forms a common exhaust from said housing and said furnace.

An asphalt analysis furnace system that enhances the airflow and combustion of asphalt-aggregate compositions, said furnace system comprising:

• a furnace, that includes a source of microwave radiation and a susceptor for absorbing the microwave radiation and converting it into heat;
• a housing around said furnace;
• a first fan that pulls air though said furnace;
• a second fan that pulls air between said furnace and said housing, but not through said furnace;
• a furnace exhaust pipe in communication with said first fan;
• a housing exhaust pipe in communication with said second fan;
• and
• a junction between said exhaust pipes that forms a common exhaust for both of said fans.

A method of analyzing the aggregate content of asphalt-aggregate compositions, the method comprising:

• heating a sample of an asphalt-aggregate composition to combustion in a furnace by directing microwave radiation into the furnace;
• drawing an airflow into, through, and out of the furnace to promote the combustion of the asphalt in the composition;
• drawing a separate airflow around and past but not through the furnace to help moderate the exterior temperature of the furnace without interfering with the combustion therein;
• and
• blending airflow that has exited the furnace with the airflow that has passed the exterior to thereby moderate the temperature of the furnace-exited airflow.