The aim of this work is to study the structural and dynamic properties of calcium aluminosilicate glasses CaO-Al2O3-SiO2 (CAS) by classical molecular dynamics, using an empirical potential of the Born-Mayer-Huggins type, built on the basis of ab initio molecular dynamics (AIMD) and the experimental results. This potential proves to be transferable for all concentration and the structural and dynamic properties studied. The evolution of structural properties has been studied as a function of temperature and silica content for the three concentration ratios R = [CaO]/[Al2O3]= 1, 1.57 et 3. The results reveal the presence of non-bonding oxygen, oxygen triclusters and AlO5 structural units for all the concentrations whose number decrease with increasing silica content. The study of the temperature evolution of the viscosity and structural relaxation time shows that the fragility decreases with the increase of silica content for all values of R. A correlation with the evolution of the number non-bonding oxygen indicates that they play a preponderant role for the fragility. It is shown that the mode coupling theory can be applied to the dynamics of the CAS and that a violation of the Stokes-Einstein relation occurs well above the experimental melting point indicating a dynamical heterogeneity. Keywords: calcium aluminosilicate, diffusion, viscosity, fragility, BMH potential, molecular dynamics, dynamical heterogeneity, non-bonding oxygen.
