Once all free surfaces have been soaked, liquid which continues to exit from the sheared granules gradually fills the voids between granules and/or coarser grains experimented for the . Cohesion decreases as granular suspension is created in some regions of the mixer and corresponding liquid bridges vanish. Consequently, power consumption decreases, although large power fluctuations remain present as a result of heterogeneities between saturated and unsaturated sheared zones.
For the concrete batching plant, in dry components, groups of powder elements naturally form. These microstructural elements are referred to as agglomerates. The voids between agglomerate particles create the agglomerate porosity. The liquid injected into the powder spreads into droplets, which are then coated by fine particles and agglomerates, hence forming granules. A number of liquid bridges are formed and yield an increase in power consumption. Heterogeneities in
the liquid distribution also stimulate increased power fluctuation.
Granules consolidate by shearing. The liquid squeezed out serves to glue the dry powder which is still present in the mixture and enlarge the granules of the . The granules increase yet remain dry at the surface. The power dissipation is mainly frictional with no reason to significantly increase. The dry powder progressively consumes to form granules.
When dry powder is consumed, the liquid released by granule consolidation gradually wets free surfaces. Cohesion strengthens with the quantity of liquid bridges formed and produces a sizable increase in power consumption. Heterogeneity between the wet and still dry granules generates high power fluctuations over time. When power consumption reaches a peak value, wet granules cover almost the entire mixed volume. The mixture becomes a"hard paste"displaying a "raspberry-like shape", as characterized by a high consistency that generates a very irregular free surface.
