Dynamics of Dissolution/Polymerization in Phosphate-based geopolymers

Phosphate-based geopolymers (PBGs) have gained much attention in recent years as an alternative route to the more studied alkali silicate-based geopolymers, as they have shown better thermal and mechanical performances. PBGs are the products of the room-temperature reaction between metakaolin and a diluted phosphoric acid solution and are composed mainly by an amorphous aluminophosphate matrix. While many efforts are being made in the study of their structural units’ identity and connectivity, much is still unknown about the dissolution/depolymerization/condensation reactions involved in the build-up of the structure. For this reason, we propose to investigate the dynamics of the system during the polymerization stage by employing SAXS-XPCS, to get an insight into the aggregation and gelation processes, which are intimately related to the PBG rheology and final microstructure. The results will provide fundamental data to gain control of PBG properties acting on synthesis parameters.