Ruggedness evaluation of AASHTO TP4: the Superpave gyratory compactor

The Strategic Highway Research Program (SHRP) developed a new compaction device for producing asphalt mixture specimens for which volumetric and mechanical properties can be measured. That device is the Superpave Gyratory Compactor (SGC). To accommodate its use, the American Association of State Highway and Transportation Officials (AASHTO) developed a provisional standard for preparing specimens by means of the SGC based on Superpave test procedures originally developed by SHRP researchers. This provisional standard is known as AASHTO TP4. At the request and under the direction of the Federal Highway Administration (FHWA), a ruggedness evaluation of AASHTO TP4 was designed. Experimental features were presented to the FHWA Superpave Mixtures Expert Task Group (ETG). The ETG assigned a small task force to review and assist in refinement of the experiment. With the help of this task force, the final experimental design was developed. The design consisted of a concise description of the AASHTO TP4 procedure including its role in Superpave and the details of the experiment to evaluate the ruggedness of AASHTO TP4. The ruggedness evaluation was designed using principles in ASTM C1067-87. Details of the experimental program to evaluate AASHTO TP4 using procedures outlined in ASTM C1067-87 are presented in this report, followed by an analysis of the data.