Abstract: SCC-DV-Xα computational method of quantum chemistry is used to study the relationship among structure, property and chemical bond of five cement minerals in the system CaO-Al₂O₃, as well as the effect of sodium ion entering into its lattice on property of the mineral. The calculated results show that the order of Ca-O covalent bond strength is C₃A < C₁₂A₇ < CA < CA₂ < CA₆,and the strength of their Ca-O bonds is all less than that of the Al-O bonds, which are consistent with the experimental results of hydration activity of the corresponding cement minerals. After sodium ion entering into the structure of C₃A, Al-O bonds will be strengthened, the hydraulic activation energy is increased, and the density of states is decreased. These are believed as the main reasons for the decrease of hydration activity of doped C₃A.

Key words: Aluminate cement minerals, chemical bond, hydration activity, quantum chemistry calculation