Influence des paramètres de formulation sur la texturation et la structuration des géopolymères

Abstract : In the context of conditioning of nuclear waste, geopolymers represent a potential alternative to conventional hydraulic binders. Currently, it is recognized that the formation of geopolymer proceeds according to a mechanism of dissolution - restructuring - polymerization resulting in a solid material. Despite the availability of many studies to understand these mechanisms, the precise relationship between the chemical nature of the activating solution, the geopolymerization process and the final microstructure should be determined from the point of view of the texturing and the structural evolution of the material. In this work, several parameters were studied: the nature of the alkali activator, the silica concentration and the addition of an aluminum source. It appears that the chemical environment of the silicate or aluminosilicate precursors is controlled by the activating solution composition. During the consolidation of the geopolymer network, these precursors play an important role on the dissolution rate of metakaolin, the size, the rearrange¬ment and the aggregation of aluminosilicate oligomers involved in the porous solid network formation. Subsequently, some characteristics of the porous network which are controlled by the size and the rearrangement of oligomers vary slightly over time. The refinement of the porosity associated to first, a densification of the solid network, and secondly, a partial closure of the porosity at the nanometer scale leads to an increase in the pore size and a decrease of the pore volume.
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Prune Steins. Influence des paramètres de formulation sur la texturation et la structuration des géopolymères. Autre. Université de Limoges, 2014. Français. ⟨NNT : 2014LIMO0002⟩. ⟨tel-01083951⟩

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