Search

In this work, we study the effect of maximum packing fraction of powders on the rheology of geopolymer pastes. A large range of metakaolin powders is generated either by blending or grinding powders. Blends of metakaolin with quartz and limestone are also studied. We show that the compressive packing model is able to predict correctly over a wide range of values the maximum packing fraction of these powders. We show that an increase of the maximum packing of powders leads to a decrease of the viscosity of geopolymer suspension at a constant solid volume fraction. We finally show that the viscosity of studied geopolymer suspensions can be well predicted by the Krieger Dougherty relation. We suggest that the highest potential degree of freedom allowing for the control of the viscosity of geopolymer pastes without modifying the composition of the suspension lies in the maximum packing fraction of the solid powders. [ABSTRACT FROM AUTHOR]

The aim of this study is to assess the effects of the addition of aluminum (NaAlO 2 ) into the activating solution on the geopolymerization reactions and the characteristics of the porous network. It was established by liquid state NMR that the speciation of the aluminosilicate oligomers and then the mean degree of polymerization were modified by the addition of sodium aluminate in the activating solution. Time-resolved SAXS and rheology results on geopolymer pastes showed that the molar ratios Si/Al and (Si + Al)/Na 2 O in the activating solution play a major role in the geopolymer properties at liquid and solid state. Indeed, the geopolymer percolating network appeared sooner and the properties of the porous network were dramatically changed with the addition of the NaAlO 2 . On the other hand, two geopolymers having identical final chemical composition but a different activating solution composition, showed to the same setting time and the same porous network characteristics. [ABSTRACT FROM AUTHOR]