Siham Kamali-Bernard | Searcharxiv

arXiv2020

Assessment of mechanical, thermal properties and crystal shapes of monoclinic tricalcium silicate from atomistic simulations

The two most common polymorphs in industrial alite, $M_1$ and $M_3$, were characterized at the molecular scale. Different methods were employed and discussed to assess mechanical properties and specific heat of both polymorphs. The calculated homogenized elastic moduli and specific heat were found in good agreement with experimental measurements. A comparative analysis of spacial Young's modulus reveal isotropic and anisotropic spacial distribution for $M_1$ and $M_3$ respectively. A more isotropic compressive strength is also reported for $M_1$ when compared to $M_3$ polymorph. Cleavage energies computation allowed to proposed equilibrium shapes for both polymorph, with significant differences. While the lowest cleavage energies were found along (100) and (001) for both polymorphs, the constructed $M_1$ crystal possesses 3 independent facets, against seven for the $M_3$ polymorph.

cond-mat.mtrl-sci↗

arXiv2020

Ab initio molecular dynamics description of proton transfer at water-tricalcium silicate interface

For the first time, an ab initio molecular dynamics simulation was performed to describe the C$_3$S/water interface. The simulation shows that oxides with favorable environment are protonated at first, creating very stable hydroxide groups. Proton transfers occur between water and silicates, and between water and hydroxides formed upon water dissociation on the surface. The typical lifetime of these events is on the same timescale than interconversion between Eigen and Zundel ions in bulk water. At the very early stage of the hydration encompassed by our simulation, silanol groups are very unstable and molecular adsorption of water is slightly more stable than dissociative adsorption.

cond-mat.mtrl-sci↗