Résumé
Gels are crucial components in many construction materials like concrete (calcium silicate hydrate gel) or geopolymers (alkali aluminosilicate gel), and can also cause damage as secondary phases (alkali silica reaction gel). We have been studying silica-based gels using theory and experiments to examine gel formation and evolution across various scales. We first studied the impact of alkali silica reaction gel formation on cement matrices, developing accelerated simulations to analyze gel formation, drying, and calcification. We then explored the high-pH effect in geopolymer formation, separating it from the aluminum effect. Using accelerated molecular dynamics simulations, we observed the formation of 1 nm grains under high-pH conditions, in agreement with experiments. Currently, we are upscaling simulations from the atomistic scale to the mesoscale, using metadynamics to improve configuration sampling. Our findings suggest that pH regulates grain size and aggregation, aligning with previous experimental and simulation results.