Volumetric and Mechanical Performance Properties of Superpave Mixtures

This investigation was carried out to study the volumetric and mechanical performance properties of the Superpave mixtures SP-1 and SP-2 and a typical Taiwan mixture (TTM). Both the Marshall and the Superpave mix design procedures were used to produce these mixtures, and the Superpave gyratory compactor was used for realistically compacting specimens to densities achieved under actual pavement conditions. These three mixtures were tested using the Superpave shear tester for conducting a simple shear test at constant height, frequency sweep test at constant height, and repeated shear test at constant height. Volumetric analyses of specimens showed that the TTM mixture hardly met the Superpave volumetric requirements and it contained less than 1% air voids at Ndesign, which strongly suggests that this mixture might be highly prone to rutting. The design asphalt content of each mixture was found very close to the peak of its compaction slope-asphalt content curve. Mechanical test results indicated that the Superpave mixtures were more resistant to permanent deformation than the TTM mixture.