One-Part Geopolymer Mixes from Geothermal Silica and Sodium Aluminate

Abstract

In geopolymer technology, silicate solutions are frequently used as alkali activators to dissolve the solid aluminosilicate precursor and aid in binder formation. These corrosive and often viscous solutions are not user-friendly and would be difficult to use for bulk production. Developing geopolymers as a one-part mixture (“just add water”), similar to Portland cement, increases their commercial viability. Here, for the first time, the geopolymer system consisting of geothermal silica and solid sodium aluminate (providing the solid silica, alkali, and alumina sources) is studied. The effects of water content, high early silica, and high early alumina in the formation of one-part mix geopolymers are also investigated. This system demonstrates that making geopolymers from solid sources by “just adding water” is possible. XRD shows that the formulation with less water has an unexpected greater extent of crystallinity. It is also observed that a high early Al concentration inhibits geopolymerization, while a high early Si concentration enhances the reaction.