Effect of Aggregate Gradation on Asphalt Mixture Compaction Parameters

Abstract

In this study, the effect of aggregate gradation on asphalt mixture compactability was investigated. Based on different combinations of coarse and fine aggregates, four gradation zones were defined: coarse pack, coarse dense pack, fine dense pack, and fine pack. Two main compaction parameters (the compaction slope and initial density) and three gradation parameters (chosen to describe the representative size and uniformity of the gradation) were compared. Statistical analyses indicated a significant correlation between the two compaction parameters as response variables and three gradation parameters as explanatory variables. These relationships were used to determine the optimum aggregate gradation with respect to asphalt mixture compactability and rutting performance. The models developed using the gradation parameters were used with two independent data sets (one from a laboratory experiment and one from a field project) to show that the parameters can predict the compactability behavior of asphalt mixtures.