Computational Material Modeling of Hydrated Cement Paste Calcium Silicate Hydrate (C-S-H) Chemistry Structure - Influence of Magnesium Exchange on Mechanical Stiffness: C-S-H Jennite.

摘要

Cementitious materials have material, geometric features ranging from molecular/nano, micro-, meso- and macro scales. Features and changes in material chemistry/nano scale influence the hydration process, formed micro scale morphology, associated properties and behavior at engineering length scales. In the present paper, effect of material ion exchange on mechanical stiffness properties of nano level hydrated cement paste constituent - calcium silicate hydrate (C-S-H) based on its material chemistry structure are studied following a molecular dynamics (MD) computational modeling methodology. Calcium ions are replaced with Magnesium ions in traditional C-S-H Jennite crystal structure of the hydrated cement constituent. Traditional C-S-H Jennite structure, and Magnesium modified structures obtained by calcium exchange of magnesium are used in the MD based material modeling analysis. Extensive modeling analysis established optimal computational MD modeling parameters and molecular material sizes employed. The present study clearly shows the influence of material chemistry due to Magnesium ion exchange in CSH-Jennite with predicted elastic modulus that changes with the level of Magnesium in CSH-Jennite material chemistry structure.