Aggregation and breakage kinetics of fresh cement paste

The influence of shear-induced forces on the microstructure of fresh cement pastes was studied. Aggregation and breakage kinetics of the paste matrix are highly influenced by the shear history. It was found that the kinetics of re-aggregation is relatively slow, and time scale for recovery is longer than the time needed for breakdown. When the aggregation kinetics dominates, network interactions among particles develop and the average floc size increases. When the breakage kinetics dominates, network interactions among particles are broken and are accompanied by a decrease in the average floc size. The results suggest that there is a limiting size to floc growth. Minor additions of clays can significantly impact the structural network development and result in a more flocculated structure. The flocs produced by the clays were highly stable flocs with strong interparticle bonds that were able to oppose floc breakage and floc erosion.