CementFF4: Formal atomic charge polarizable force field for cementitious systems – Bulk and surface

A general-purpose formal charge polarizable force field for cementitious systems, CementFF4, is presented. The force field includes the following species: Ca, Si, O, H, Al, Zn, OH⁻ and H₂O. The force field is a significant extension of previous force fields and is validated by comparison of structural features, elastic constants, reaction enthalpies, and vibrational density of states to experimental and ab initio values for known crystals. Particular attention is given to the tobermorite 14 Å structure, due to its similarity to the main hydration phase of Portland cements, calcium silicate hydrate. The results are in very good agreement with experimental and ab initio data over the entire range of simulated properties (less than 5 % deviation on structural properties and less than 10 % on mechanical properties for non-hydroxide minerals).