The notion of compactability has been repeatedly used in this text, especially in Chapter 10. Compactability (i. e., susceptibility to compaction) can be defined as the ability of an asphalt mixture to change density under the influence of compactive effort; or to put it another way, compactability is the material feature determined by the amount of energy necessary for the compaction of a given mass into the smallest volume (Schabow, 2005). Resistance to compaction is the reverse of compactability. Generally, it means that compactable mixtures (with a low resistance to compaction) do not need a lot of compactive effort.
Resistance to compaction is connected with features of a mixture, such as the gradation of the aggregate mix and the aggregate properties, which include the following:
• Content of crushed stone
• Particle microtexture
• Particle shape
• Hardness (resistance to crushing and wearing)
Additionally, resistance to compaction is also affected by the content and type of binder and its viscosity at the compaction temperature.
Compactability is tested in Europe in accordance with the European standard EN 12697-10, which provides for the following two methods for testing and assessing the compactability asphalt mixtures: [70]
The following equipment can be used for testing compaction resistance and comparability according to EN 12697-10:
• Impact compaction (Marshall hammer) according to EN 12697-30
• Method I—results as compaction resistance C (units [42 Nm])
• Method II—results as compaction resistance T (units [21 Nm])
• Gyratory compaction according to EN 12697-31
• Method I—not used
• Method II—results as compactability K (dimensionless)
• Vibratory compaction according to EN 12697-32 (not applicable to SMA)
• Method I—results as compactability k (dimensionless)
• Method II—not used
