Geopolymer Nucleation by new atomistic upscaling computation for aggregating aluminosilicate tetrahedral units


“(A) Formation of Si-O-Si and Si-O-Al bonds which respect the β angle and tetrahedral geometrical constraints. (B) Tetrahedron constraints are expressed with four points ABCD on the unit sphere (coarse-grained particle) during the binding (particle association/aggregation) process. (C) The final status of the simulation: The particles, clusters, and pore distribution are on the left side. Details are illustrated on the right side. Local details about the porosities and the distribution are shown on the right: the dark aqua marine colored particles represent the four different types of monomer building units, and the yellow particles represent the pore sizes.

This paper presents a 3D off-lattice coarse-grained Monte Carlo (CGMC) approach to simulate the nucleation of alkaline aluminosilicate gels, their nanostructure particle size, and their pore size distribution. In this model, four monomer species are coarse-grained with different particle sizes. The novelty is extending the previous on-lattice approach by implementing a full off-lattice numerical implementation to consider tetrahedral geometrical constraints when aggregating the particles into clusters. The obtained equilibrated nano-structure was digitized to obtain the pore size distribution and this was compared with the on-lattice CGMC and measurement results. The observed difference highlighted the importance of the developed off-lattice CGMC approach to better describe the nanostructure of aluminosilicate gels.