Influence of Cu Doping on the Hydration of Dicalcium Silicate: A First-Principles Study

Using copper tailings to produce cement clinker can result in Cu-doping and affects the hydration characteristics of dicalcium silicate (C2S). In this work, density functional theory static calculation and ab initio molecular dynamics (AIMD) simulation are used to investigate the hydration properties of Cudoping beta-C2S. The static calculation shows that Cu-doping influences the crystal and electronic structure of beta-C2S and leads to charge localization. Cu-doping also promotes the dissociation adsorption on the surface around the Cu atom and weakens the chemical constraint on Ca-OW and HW-OS. The AIMD simulation shows that water molecules on the Cu-doped beta-C2S(1 0 0) surface prefer dissociation adsorption and maintain the dissociated state for a long lifetime. The local weak interactions between water and the Cu atom are enhanced, and the bond concentration of Ca/Cu-OW on the whole surface decreases. This higher hydration reactivity by introducing Cu atoms would promote the application of copper tailings and the C2S phase for cement green production.