Assessment of Mechanical Stability Performance of Asphalt Mixture Using Superpave Gyratory Compactor

Abstract

This study focused on developing a gyratory compactor to be used as a basis for measuring the stability of asphalt mixtures without the need for additional equipment or additional time. This was achieved by modifying the gyratory compactor measurements. A load cell was provided to the compactor which allowed measuring the variation of forces on top of the samples during the gyrations. Different asphalt mixtures were produced using two different aggregate sources, different aggregate gradations, and different asphalt contents. A Superpave gyratory compactor (SGC) was used to compact all the mixtures. The SGC produced densification curves that were used to determine volumetric properties of the mixtures. It was necessary to evaluate the construction and the densification caused by the traffic loading. Depending on the results of analysis for the mixtures, the obtained correlation between the traffic force index (TFI) and Marshall stabilty revealed a coefficient of determination of about 86%, which indicates a strong relationship between Marshall stability and the TFI. Therefore, it was concluded that the TFI can be adopted as an indication of mechanical stability for a mixture. Good correlation was obtained between the construction densification index (CDI), which is a measured value derived from the rate of change of the height of the specimen between 92% and 98% Gmm, and the traffic densification index. Another measurement of the load cell was the measured compaction shear forces of a wide spectrum of hot-mix asphalt (HMA) mixtures that were used to calculate a stability index referred to as the gyratory stability (GS).