Hierarchical geopolymers by ice-templating

Hierarchical geopolymers with mesoporous matrices and lamellar macro-porosities were produced by an ice-templating (freeze-casting) technique. Ice-templating allows to fabricate porous materials with main unidirectional oriented pores and a high open porosity where the final component results in a lamellar or laminate-like structure. Starting from a mixture of metakaolin and potassium silicate aqueous solution, the goal was to promote the simultaneous formation of geopolymer intrinsic mesoporosity and lamellar macroporosity by unidirectional ice growth together with a final chemical consolidation. Geopolymerization was triggered through a maturation step without reaching a complete consolidation and different amounts of water were mixed to the geopolymer paste to obtain different lamellar structures. The most promising geopolymer composition was selected to produce lamellar monoliths. With regards to enterprises: ISTEC is able to produce geopolymer monoliths with 10 mm diameter and 25 mm height and to characterize them in terms of macro- and micro-structure, intrinsic and induced porosity size distribution and specific surface area. TRL 3