Compaction Factor is the ratio of the weight of partially compacted concrete to the weight of the concrete when fully compacted in the same mould. The weight of partially compacted concrete in relation to its fully compacted state is a reasonably good indication of the workability of concrete.

The main features of this apparatus is as follows :
* Portable.
* Frame is rigid and stable.
* Removal and cleaning of hoppers and receiver is easy.
* Instantaneous opening of trap doors at the back when released and during the fall of material.
* Especially useful for workability determination of concrete mixes of very low workability such as compacted by vibration.