Towards a mesoscale model of geopolymers: Interaction potential from the molecular scale

Geopolymers are alumino-silicate hydrates obtained by reaction of an alumino-silicate source (e.g. metakaolin or fly ash) with alkali solution. Geopolymer-based binders are less environmentally impacting than ordinary cement, but their implementation in the construction field is still limited and requires a better understanding of the nanoscale origin of their mechanical properties. This understanding can be advanced with new simulations based on interaction-driven aggregation of nanoparticles, similar to what has happened in the last decade in the field of traditional cement science. This paper introduces a pathway to develop such a model starting from recent molecular models of geopolymers, which allow to compute the interaction potentials needed for the larger mesoscale. Interaction potential parameters are presented in this work as a function of different particle sizes, targeting experimentally-observed ranges of particle sizes and porosity. Overall, this work opens new opportunities to understand the linkage between mesostructure and engineering properties of geopolymers, with the aim of supporting their commercialisation as alternative cements and, in this way, contributing to the development of a greener economy.