Séminaire - Simulation of silicate solutions and gels at the atomic scale​ - Romain Dupuis

Jeudi 7 novembre 2019 14 h

IMPMC - Sorbonne Université - 4 place Jussieu, 75005 Paris, tour 23, 4^e étage, couloir 22-23, salle 401

Romain Dupuis - MIT Concrete Sustainability Hub, Massachusetts Institute of Technology

Abstract

The formation of silicate species is a complex issue that has to be resolved to investigate manifold synthetic and natural materials (cement, geomaterials, minerals). For instance, the gelation depends on the pH of the initial solution, the water to silicon ratio or the ionic concentration. Simulations can provide detailed information on the structuration of silicates and on their chemical properties. We have recently developed a method to reproduce efficiently the formation of pure silica gels. The key features are in good agreement with experimental data[1]. 

Using cost-efficient methods, we are now able to play at will with the chemical properties. ​We will present new results on systems ranging from the pure silica gel to complex alkali-silica solutions. For instance, we modified the water to silicon ratio to observe the restructuration of gels. We noted a passivation effect that protects dense gels from dissolving, due to the formation of silicate cages. This passivation effect cancels out when pH is high. Knowing the gels structure will help us to go to larger scales simulations and investigate the interaction between gels, solutions and solids.

[1] R. Dupuis, L. Beland, R. Pellenq, Physical Review Materials, 2019