Effect of alkali metals on the preferential geopolymerization of stilbite/kaolinite mixtures

Stilbite is used as the main aluminosilicate oxide source to determine the effect of various factors on the extent of geopolymerization of stilbite/kaolinite mixtures. Increasing the M2O/H2O ratio (where M = Na and/or K) results in an increase in the dissolution of aluminum and silicate species from stilbite and kaolinite, which therefore leads to an improvement in the compressive strength of the geopolymer. The SiO2/M2O ratio affects significantly the degree to which polymerization between Al(OH)(4)(-) and Si complexes can occur. The results also show that Na+ compared with K+ enhances the dissolution of aluminum and silicate species. However, K+ improves the compressive strength of the geopolymer compared with Na+. It has been established for the first time that kaolinite and stilbite react differently with different alkali metals. The successful geopolymerization of stilbite/kaolinite mixtures can occur only by homogeneously dispersing condensed Na2SiO3 in a MOH solution prior to adding solids.