Fundamental development of the particulate percent packing efficiency combining both coating particulate and asphalt aggregate packing technology

Abstract

A primary objective of this study was to evaluate how the more fundamental blending approach to optimize the packing of pigments in coatings can potentially be used to improve the packing of the asphalt-aggregate blends. In the course of this study, a new way to characterize the efficiency of the packing of particles was developed from the particle packing fraction analysis originally included as a component of a previously published suspension viscosity model. This new percent packing efficiency introduced in this study was found to be particularly useful in evaluating the packing efficiency for particle distributions of all sizes. The large scale of the aggregates in asphalt previously published in the Goode and Lufsey study along with the properties included in their report was very useful in developing the formulation for this new percent packing efficiency analysis. A property analysis of the Goode and Lufsey study data found that the minimums for the mineral voids and the air voids appear to correspond with the maximums for percent packing efficiency as well as the maximums of the bulk-specific density. These results appear to indicate that the percent packing efficiency can be a significant measure of the efficiency of particle packing for aggregate blends. These preliminary analysis results also suggest that the percent packing efficiency may also be able to detect unstable particle packing applications for particle distributions of all sizes as well as potentially unstable asphalt/aggregate applications. As anticipated, the Goode and Lufsey maximum density standard gradation did yield the maximum percent packing efficiency followed in order by other standard gradations including a stone matrix gradation, the superpave gradation, and finally, a Bailey gradation. Finally, several new gradations were identified in this study that could potentially offer significant property improvements over both gradation 3 from the Goode and Lufsey study as well as the other current aggregate gradation standards for the asphalt industry.