Impact of the mastic phase and compaction temperature on the sigmoidal gyratory compaction curve of asphalt mixtures

•The sigmoidal compaction curve is presented as a method to assess compaction data.•Mastic phase and compaction temperature were considered to influence compaction.•The mastic phase had a more pronounced impact than the effect of compaction temperature.•Two space diagrams are proposed to demonstrate changes in workability/compactability. In this study, the compactability and workability of asphalt mixtures are assessed in retrospect to key mix design factors. To better understand how the compactability and workability of asphalt mixtures evolve, asphalt mixtures compacted at different temperatures and asphalt mixtures with various mastic compositions were considered. The gyratory compaction data were further analysed using a sigmoidal curve model. To track changes in the mastic phase, the mastic film thickness and the mastic stiffness indicator (MSI) were considered. The sigmoidal curve parameters revealed that the mastic film thickness had a more pronounced effect on the compaction process compared to the effect of compaction temperature. Finally, two space diagrams are proposed for the assessment of compactability and workability, namely the C0 (initial compacity) versus CCIP (compacity at the inflection point), and the plot of β4/β3 versusβ3, with β4 and β3 being shape parameters of the sigmoidal curve.