Mineral additives geometry influence in cement pastes flow

The flow behaviour of a fresh cement paste is dependent on its solid composition, but it cannot be predicted solely from the physico-chemical properties of the solid phase. The variation in rheological parameters (viscosity or consistency, index flow, and yield stress) was investigated on the basis of the geometric aspects of the solid additives (fly ash and silica fume) that were used in place of cement particles in the final composition of the pastes. The spherical particles (fly ash) showed a lower viscosity (consistency) and a weaker network (lower yield stress) when the water/binder ratio decreased. On the other hand, a higher polydispersity of the solid particles (silica fume) yielded an increase in the viscosity (consistency) and the yield stress. In both cases, the flow index was not affected by cement particle substitution.