Capitolo 2: Materie Prime

The reaction of a solid aluminosilicate with a highly concentrated aqueous alkali hydroxide (KOH, NaOH) and/or silicate (potassium or sodium silicates) solution produces a synthetic amorphous to semi-crystalline alkali aluminosilicate material, i.e. a geopolymer which is X-ray amorphous analogues of zeolites. During geopolymerization a gel network is formed, consisting of SiO4 and AlO4- tetrahedra linked in an alternating sequence. The raw powders are mainly meta-kaolin and industrial wastes such as fly ashes, but also natural minerals, blast-furnace slags or any source of silica and alumina