Relation between reactivity and electronic structure for α′L-, β- and γ-dicalcium silicate: A first-principles study

The effect of the electronic structures of alpha'(L-), beta-, and gamma-dicalcium silicate (alpha'(L-), beta- and gamma-C2S, C=CaO, S=SiO2) on hydration reactivity have been investigated by first-principles calculations. Active O atoms with larger charge densities are found in alpha'(L)- and beta-C2S, while they are absent in gamma-C2S. The local density of states of valence band maximum in a'r and beta-C2S is highly localized around active O atoms, whereas that in gamma-C2S is homogeneously dispersed. For the active O-2p orbital in ail: and beta-C2S, the highest orbital energy in the partial density of states is about 0.31 eV higher than that of the inactive O in gamma-C2S. These differences make the active O atoms of alpha'(L-) and beta-C2S more susceptible to electrophilic attack and result in higher hydration reactivity for alpha'(L-) and beta-c(2)s. (C) 2013 Elsevier Ltd. All rights reserved.