Determination of proper mixing and compacting temperatures of laboratory fabricated asphalt concrete specimens.

PDFTech ReportFHWA-OR-RD-95-11SPR 5263Asphalt concreteSpecimensTemperatureMixingCompactionOregonOregon. Dept. of TransportationSosnovske, DanOregon. Dept. of TransportationUnited States. Federal Highway AdministrationUS Transportation CollectionThe Oregon Department of Transportation (ODOT) Materials Unit has historically used one temperature for the mixing and compacting of laboratory fabricated asphalt concrete specimens. Since switching to the performance based asphalt (PBA) specifications in 1991, the Bituminous Design Crew has continued to use the same specimen preparation technique. However, the method of recommending mixing and lay-down temperatures for construction relies on a viscosity based system. The objectives of this study are to evaluate the differences in physical properties between specimens prepared using the constant temperature technique and a viscosity based temperature selection technique. The physical properties analyzed are: air void content, Hveem stability, Index of Retained Modulus and Index of Retained Strength. Because of the small sample size and the small differences in the mixing and compacting temperatures used in this study, no difference in physical properties could be identified for the two temperature selection methods. It is recommended that the Materials Unit adopt the viscosity based temperature selection method in anticipation of switching to the SHRP PG asphalt grading system and the SHRP gyratory method of compaction