Investigations about the influence of fine additives on the viscosity of cement paste for self-compacting concrete

In this work, the effect of fine additives (limestone, silica fume, fly ash, pozzolan, nano-silica fume) on the plastic viscosity of cement paste is being investigated. Towards this direction, twenty-four samples were designed and produced. Those pastes consisted mainly of cement (type CEM I 42.5) and specific proportions of one or two fine additives. Plastic viscosity and yield stress were measured, as well as micro-structure of selected 28-days hardened samples was studied through means of mercury porosimetry. Results showed that limestone (40%) can improve the rheological behavior of cement pastes, and the synergy of limestone (20%) and fly ash (20%) can lead to higher packing density. Cement pastes that combine those two characteristics, could serve as the base for self-compacting concrete (SCC) production.