In-mold pressure verification device

#The invention relates to a device for measuring pressure, and more particularly to a device for verifying the pressure in a Superpave gyratory compactor.

#The Strategic Highway Research Program (SHRP) has developed a standard for testing the physical properties of a bituminous asphalt paving mix, using a device known as the Superpave gyratory compactor. The Superpave gyratory compactor produces compacted cylindrical test specimens of the asphalt paving mix for determining volumetric and mechanical properties. The compactor simulates the kneading action of the large rollers used to compact asphalt pavement during highway construction. A specimen of the asphalt paving mix is placed in an open-ended cylindrical mold, with circular disks or plugs being placed at opposite ends of the mold. The gyratory compactor device applies pressure to the specimen in the mold while gyrating the mold at a specified angle to produce a gyratory kneading action. The Superpave gyratory compactor specifications call for the mold to be gyrated at a compaction angle of 1.25 degrees operating at 30 rpm while applying a consant pressure of 600 kPa.

#Several manufacturers produce gyratory compactors according to the Superpave gyratory compactor specifications. Gyratory compactors of this type are described for example in the following U.S. Pat. Nos. 5,323,655; 5,456,118; 5,606,133; 5,939,642; 5,817,946; and 6,026,692.

#Having thus described the invention in general terms, reference will now be made to the accompanying drawings, which are not necessarily drawn to scale, and wherein:

#FIG. 1 is an exploded perspective view showing a system for dynamically measuring the pressure within the mold of a gyratory compactor;

#FIG. 2 is a cross sectional view showing the pressure verification system installed in a gyratory compactor;

#The present invention now will be described more fully hereinafter with reference to the accompanying drawings, in which preferred embodiments of the invention are shown. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. Like numbers refer to like elements throughout.

#The pressure verification device of the present invention is designed to be used with any of the Superpave gyratory compactors which are presently available commercially. Illustrative but non-limiting examples of gyratory compactors which can utilize the pressure verification device of the present invention are described in the following U.S. Pat. Nos. 5,323,655; 5,456,118; 5,606,133; 5,939,642; 5,817,946; and 6,026,692.

#A Superpave gyratory compactor of the type described utilizes a cylindrical mold for producing a cylindrical test specimen from a sample of asphalt paving mix. In FIG. 1, the cylindrical mold is indicated generally by the reference character 10. The mold 10 includes a cylindrical side wall 11 which is of a substantially uniform inner diameter and has open opposite ends. The particular mold 10 illustrated in FIG. 1 has out-turned flanges 12 adjacent the upper and lower ends of the cylindrical wall 11 which provide engagement surfaces cooperating with components of one particular design of a commercially available gyratory compactor apparatus so that the gyratory compactor apparatus can hold the mold and impart a gyratory motion to it. However, some gyratory compactor designs do not require a flanged mold. Therefore, it should be clearly understood that the flanges 12 shown in FIG. 1 are not an essential part of the present invention, and the invention can be operated with other mold designs, including those having a single flange or having no flange, or having other auxiliary elements provided on the mold to cooperate with a particular design of gyratory compactor.