Blast furnaces; Chemical activation; Differential scanning calorimetry; Gels; Hardness; Inorganic polymers; Kaolin; Melting; Silicates; Slags; Strength of materials; Synthesis (chemical); Thermogravimetric analysis; Water; X ray diffraction analysis; Geopolymers; Composite materials
Abstract :
[en] Alkali activation of dehydroxylated kaolin or clay yielded high-strength polymeric materials, so-called geopolymers. They were synthesized by mixing the aluminosilicate with solutions of sodium metasilicate and KOH followed by adding 45 wt.% of ground-granulated blast furnace slag. The influence of the aluminosilicate source, its activation temperature, and the order of mixing raw materials were studied on the workability of the blending paste, the microstructure, and the Vickers hardness of the geopolymer samples. The polymeric material is completely amorphous according to x-ray diffraction. Solid-state 27Al and 29Si magic-angle-spinning nuclear magnetic resonance showed that the geopolymer consists of AlO 4 and SiO 4 tetrahedra linked together through a polymeric network constituted by branched entities SiQ 4(4Al) and SiQ 4(3Al), but also by less-polymerized silicates SiQ 1 and SiQ 2. Scanning electron microscopy showed a homogeneous polymeric gel matrix containing unreacted slag (and quartz) grains; thermogravimetric analysis and differential scanning calorimetry exhibited a high content of water and an elevated melting point (1260 °C). Vickers hardness values are in the range of 200 MPa.
Disciplines :
Chemistry
Author, co-author :
Lecomte, I.; Department of Chemistry, Chemistry Institute B6, University of Liège, Sart-Tilman B-4000, Liège, Belgium
Liégeois, Monique ; Université de Liège - ULiège > Département de chimie (sciences) > Chimie inorganique structurale
Rulmont, André ; Université de Liège - ULiège > Département de chimie (sciences) > Département de chimie (sciences)
Cloots, Rudi ; Université de Liège - ULiège > Département de chimie (sciences) > LCIS - GreenMAT
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