PREDICTIONS ON THE FORMATION AND BOND PERFORMANCE OF SOME ETTRINGITESBY A QUANTUM-CHEMISTRY METHOD

Mg-, Zn- and Mn-bearing ettringites are studied by a computational qua ntum chemistry method, the self-consistent-field discrete variation X- alpha method(SCF-DV-X-alpha). Their bond order, population, net charge and covalent bond order are obtained. Because the bond order of the O -5 atom in Mg-bearing ettringite is negative, and the net charges of O -5, O-7, and O-11 atoms are positive, the Mg-bearing ettringite does n ot exist by the structure of ettringite. The bond orders of Zn and Mn atoms, and the covalent bond order of Zn-O and Mn-O bond in Zn- and Mn -bearing ettringites are higher than these of Ca and Ca-O bond in ettr ingite, so we can predict that the bond of Zn- and Mn-bearing ettringi tes is higher than ettringite. (C) 1997 Elsevier Science Ltd .