The synthesis of geopolymers based on alkaline polysialate was achieved at low temperature (∼25–80 ◦C) by the alkaline activation of raw minerals
and silica fume. The materials were prepared from a solution containing dehydroxylated kaolinite and alkaline hydroxide pellets dissolved in
potassium silicate. Then the mixture was transferred to a polyethylene mold sealed with a top and placed in an oven at 70 ◦C for 24 h. For all
geopolymer materials, following dissolution of the raw materials, a polycondensation reaction was used to form the amorphous solid, which
was studied by FTIR-ATR spectroscopy. The in situ inorganic foam based on silica fume was synthesized from the in situ gaseous production
of dihydrogen due to oxidation of free silicon (content in the silica fume) by water in alkaline medium, which was confirmed via TGA-MS
experiments. This foam has potential as an insulating material for applications in building materials since the thermal measurement has a value of
0.22Wm−1 K−1.
© 2010 Elsevier Ltd. All rights reserved.