Rheological behaviour of cement and silica suspensions: Particle aggregation modelling

Cement and silica suspension rheological behaviour is modelled by supposing that particle aggregation occurs. With two independent parameters, the variation of the shear viscosity as a function of the shear rate for cement or silica suspensions having different solid volume fractions can be predicted. The model is in good agreement with experimental data. Cement suspensions are initially very similar to unreactive silica suspensions. The values of adhesion forces obtained seem to show that the effective interaction areas are very small. It reflects the fact that in the dormant period the particles are contacting at points, which become progressively higher in surface as C–S–H precipitates at these contacts. The model used is consistent with the observed power law variation of static and dynamic yield stresses with solid volume fraction. The aggregates formed under shear seem to be very compact, which is presumably related to the large solid volume fractions of the studied suspensions.