Abstract

Granulation is a useful tool to improve the handling properties and use of alkaline-activated materials. Currently, the easiest method for large-scale preparation is high-shear mixing, while other techniques have been utilized on laboratory scale and are discussed. Attention is necessary to the granulation conditions, because in geopolymer granulation, the alkaline-activation step and the granulation step occur concomitantly, and the exothermic reaction affects the granulation conditions. Geopolymer granules appear to have a higher compressive strength than equivalent granules. A possible application is for wastewater treatment either for cationic metals and semimetals or for ammonia. Other opportunities for use are catalytic application, biogas cleaning and upgrading, or as lightweight aggregates in concrete. Further systematic research is necessary for the deeper understanding of geopolymer granulation.