Simulations of Tricalcium Silicate Dissolution at Screw Dislocations: Effects of Finite Crystal Size and Mechanical Interaction Potentials

For many minerals in solution, the relationship between dissolution rate and saturation index displays two distinct regimes, one of slow dissolution near equilibrium and the other of fast dissolution far from equilibrium, with stresses at crystallographic defects controlling the transition between the two. This leads to a characteristic sigmoidal curve between dissolution rate and supersaturation. Here, we use kinetic simulations to predict both regimes and the transition between them in finite-sized crystals with embedded screw dislocations for tricalcium silicate. The simulations employ rate equations which depend on chemical potentials and mechanical stresses and allows us to capture the whole sigmoidal rate curve. We also propose a parametrisation of the interaction potentials between Ca3SiO5 particles that returns consistent interfacial energies with water for different facet orientations. Lastly, we explore the impact of different interaction potentials on the resulting rate curves, contributing to the current discussion on engineering materials and defects to control reactivity.