USE OF VIBRATORY COMPRESSION FOR THE LABORATORY COMPACTION OF BITUMINOUS MIX TEST SPECIMENS --BITUMEN, FLEXIBLE AND DURABLE. 3RD EUROBITUME SYMPOSIUM 1985, THE HAGUE, NETHERLANDS, SEPTEMBER 11-13, 1985

For the results of laboratory tests to be valid, the test specimens must be sufficiently homogeneous. Hitherto, methods for the compaction of moulded test specimens having a slenderness ratio of two or more have been unsatisfactory in this respect. For this reason, we use specimens taken by coring or sawing from slabs compacted by the laboratory pneumatic compactor. The compaction method described here minimises these drawbacks, and is also less expensive. In the new method, the material to be compacted is subjected to a combination of a circular vibration in the horizontal plane, over its entire height, and an increasing vertical force. This paper describes the compaction machine. Tests have been carried out on materials having different compaction behaviours. The results are compared to those of the gyratory compactor compaction test and those of the static compaction used in the lcpc compression test (duriez test). The test specimens produced are of satisfactory homegeneity in terms of void volume in spite of a high slenderness ratio. Compaction is easy and rapid, and is achieved by stresses small enough not to cause attrition of the aggregates. Recording changes in the void volume of the bituminous mix during compaction should make possible a better characterization of the materials as regards compactability: this is the long-term objective. For the covering abstract of the symposium see IRRD 815173.