Molecular dynamics study of confined water in the periclase-brucite system under conditions of reaction-induced fracturing

The volume-increase associated with hydration reactions in rocks may lead to reaction-induced fracturing, but requires a stable water film be present at reactive grain boundaries even when subject compressive stress. Hydration of periclase brucite is solid volume increase ca. 110%. Recent experiments on the periclase-brucite system observed that effective mean stress exceeds 30 MPa, reaction rate slows down dramatically. We hypothesize for forming progress, fluid between grains must remain stable. If applied pressure becomes larger than force, will collapse and squeezed out contacts. To quantify this effect, we study behavior confined or surfaces stress, by performing molecular dynamics simulations. simulations are carried using ClayFF force field single point charge (SPC) model program LAMMPS. setup consists two interfaces either surrounded water. Our show reaches few tens collapses reduces one layers, while self-diffusion coefficient molecules factor eight. A thickness below layers thinner size shell around Mg2+-ions, which limit ion-transport. layer normal 25–30 MPa might explain slow-down fracturing system.