One of the best methods of laboratory compaction is considered to be Gyratory for not only the material’s assessment of compactibility but also the production of test samples. The method achieves this by the application of vertical stress, typically 600 kPa via platens to a mass of asphaltic mixture inside a 100 or 150mm diameter mold. Whilst platens are kept parallel and horizontal, the longitudinal axis of the mold is gyrated at a fixed angle to the vertical axis.

During the test process, the height of the specimen is measured automatically and the mixture density and void content are calculated.