Control of Superpave Gyratory Compactor's Internal Angle of Gyration: Experience of the Utah Department of Transportation

Abstract

The State of Utah Department of Transportation started a program to use the dynamic angle validator (DAV) to measure the internal angle of all Superpave® gyratory compactors (SGCs) used in the construction of hot-mix asphalt in the state. Results show that differences in internal angle exist unless the compactors are calibrated regularly and technicians are trained in laboratory procedures. Once the program was in place, the internal angle of 36 of the 46 SGCs tested was within the limits of 1.16° ± 0.03°. However, seven SGCs, all of one model, had angles between 0.860° and 1.212°, with an average angle of 1.026° even after calibration. If the limits are narrowed to 1.16° ± 0.02°, then only 28 of 46 (60%) of the SGCs will be within the range. Results also show that it is possible to obtain acceptable density values on specimens compacted using machines that have internal angles outside the proposed range. It was concluded that the internal angle limits of 1.16° ± 0.03° were too restrictive for the machine...