Compressed and compact bulk density

The density of a powder compressed or compacted to a degree greater than that achieved by tap densities is, at times, required as a ceramic, metallurgical or pharmaceutical end product. 

A civil engineering uniaxial oedometer or consolidometer (BS 1377-7 1990 ISO/TS 17892-5 2004) consists of a cylindrical ring container which compresses, between two porous plates, a powdered sample at known normal forces in the range 10-3200 MPa. The porous plates allow fluids (gases/liquids) to flow through the compressed media. 

A coefficient of volume compressibility or coefficient of consolidation can be calculated from the thickness, volume or void ratio versus logarithmic applied stress relationship. 

The compaction characteristic of powders obtained by this uniaxial technique may also be used to determine the elasticity, plasticity, deformation, fragmentation and coherency of cohesive and non-cohesive powders (Stanley-Wood 1983,1987). 

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