The resulting plots show that a cle

The resulting plots show that a clear negative displacement gradient develops along the height (z) of the compacts tested in water, whereas dry samples display a less-defined displacement profile in the z direction with even a positive gradient in the bottom half of the pressing tool. The negative displacement gradient measured for the wet samples indicates the development of strong compressive strains inside the compact along the pressing direction. For samples subjected to an external stress of 500 MPa, the displacements are 10-fold higher than those measured for specimens tested in the dry state under the same pressure. This shows that the presence of water clearly promotes the densification of the compact through the longitudinal displacement of vaterite agglomerates. Such longitudinal displacement arises most likely from deformation processes at the contact points between agglomerates, which change their initial spherical morphology into more densely packed truncated shapes. In contrast to the wet compacts, specimens tested in the dry state showed no detectable longitudinal displacement at 100 MPa and a relatively weak compressive longitudinal displacement at 500 MPa. The significant radial (off-axis) displacement observed in these dry specimens (Fig. 4a) suggest that the agglomerates in these compacts undergo lateral rearrangements that do not allow for an effective reduction of the material‟s internal stresses. Such behavior is typical of brittle powders subjected to uniaxial pressing.