Molecular simulation of the structure and elastic properties of ettringite and monosulfoaluminate

T Honorio and P Guerra and A Bourdot, CEMENT AND CONCRETE RESEARCH, 135, 106126 (2020).

DOI: 10.1016/j.cemconres.2020.106126

Ettringite (AFt) and monosulfoaluminate (AFm(MS)) are the two of the main hydration products of tricalcium aluminate. Ettringite formation is favored in the presence of gypsum, and monosulfoaluminate is the usual AFm phase in a system with low calcium carbonate content. In this article, a new empirical force field, AFFF, is proposed to describe the interactions among species in ettringite, monosulfoaluminate, and tricalcium aluminate at the molecular level. This force field provides structural data and elastic properties that are consistent with experimental and previous simulation results. Using AFFF, the effects of the hydration state of ettringite and monosulfoaluminate on the lattice parameters and elastic constants are studied. Regarding the molecular modeling of the elastic properties of ettringite, simulations with AFFF are considerably less computationally intensive than the other approaches used so far. These results leave room for a better understanding of the nanoscale processes that affect AF-phases behavior in cement systems.

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