The synthesis of geopolymers based on alkaline polysialate, was achieved at slightly elevated temperature, by alkaline activation of raw minerals and industrial waste. The materials were prepared from a solution containing dehydroxylated kaolinite and alkaline hydroxide pellets dissolved in potassium or sodium silicate. Then the mixture was transferred to a polyethylene mould sealed with a top and placed in an oven at 70°C during 24 hours. The addition of an industrial waste, silica fume, leads to the formation of an in-situ inorganic foam. Whatever the alkaline cation, foam formation occurs. The properties depend on the viscosity of silicate precursors due to the amount of water and to the size of alkaline.