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Formation mechanism of the hydrate phases in magnesium oxychloride cement
The formation mechanism of the hydrate phases in magnesium oxychloride cement (MOC) pastes is discussed. The major reaction products of MOC pastes (MgO-MgCl2-H2O system) has long been revealed to be four crystalline phases: 5Mg(OH)2 dot MgCl2 dot 8H2O (5 phase); 3Mg(OH)2 dot MgCl2 dot 8H2O (3 phase); 2Mg(OH)2 dot MgCl2 dot 4H2O (2 phase); and 9Mg(OH)2 dot MgCl2 dot 5H2O (9 phase). All of the phases are the basic salts whose formal formula can be written as: Mgx(OH)y dot Cl dot nH2O. It can be considered that the formation of these phases occurs neither through Mg(OH)2 and MgCl2, nor through simple ions Mg2+, Cl- and OH-, etc. It was suggested that the formation of these phases probably occurs through the polynuclear complexes (Mgx(OH)y(H2O)z)2x-y and Cl-, OH- ions. The hydrolyzing experiments for the system Mg2+-OH--H2O show that the hydrolysis of Mg2+ in MgCl2 solutions with a certain concentration can yield (Mgx(OH)y(H2O)z)2x-y. In the system MgO-MgCl2-H2O, the action of MgO is to increase the concentrations of Mg2+ and OH- ions that induce and promote the hydrolysis of Mg2+. It can be concluded that the formation of the hydrate phases in MOC pastes involves the neutralization and dissolution of MgO powder; the hydrolyzing-bridging of Mg2+ ions in MgCl2 solutions to form a number of polynuclear complexes (Mgx(OH)y-(H2O)z)2x-y with uncertain composition; and the conversion of the amorphous hydrogel consisting of (Mgx(OH)y(H2O)z)2x-y complexes, Cl- and OH- ions and H2O to the crystalline hydrate phases.
Formation mechanism of the hydrate phases in magnesium oxychloride cement
The formation mechanism of the hydrate phases in magnesium oxychloride cement (MOC) pastes is discussed. The major reaction products of MOC pastes (MgO-MgCl2-H2O system) has long been revealed to be four crystalline phases: 5Mg(OH)2 dot MgCl2 dot 8H2O (5 phase); 3Mg(OH)2 dot MgCl2 dot 8H2O (3 phase); 2Mg(OH)2 dot MgCl2 dot 4H2O (2 phase); and 9Mg(OH)2 dot MgCl2 dot 5H2O (9 phase). All of the phases are the basic salts whose formal formula can be written as: Mgx(OH)y dot Cl dot nH2O. It can be considered that the formation of these phases occurs neither through Mg(OH)2 and MgCl2, nor through simple ions Mg2+, Cl- and OH-, etc. It was suggested that the formation of these phases probably occurs through the polynuclear complexes (Mgx(OH)y(H2O)z)2x-y and Cl-, OH- ions. The hydrolyzing experiments for the system Mg2+-OH--H2O show that the hydrolysis of Mg2+ in MgCl2 solutions with a certain concentration can yield (Mgx(OH)y(H2O)z)2x-y. In the system MgO-MgCl2-H2O, the action of MgO is to increase the concentrations of Mg2+ and OH- ions that induce and promote the hydrolysis of Mg2+. It can be concluded that the formation of the hydrate phases in MOC pastes involves the neutralization and dissolution of MgO powder; the hydrolyzing-bridging of Mg2+ ions in MgCl2 solutions to form a number of polynuclear complexes (Mgx(OH)y-(H2O)z)2x-y with uncertain composition; and the conversion of the amorphous hydrogel consisting of (Mgx(OH)y(H2O)z)2x-y complexes, Cl- and OH- ions and H2O to the crystalline hydrate phases.
Formation mechanism of the hydrate phases in magnesium oxychloride cement
Deng, Dehua (author) / Zhang, Chuanmei (author)
Cement and Concrete Research ; 29 ; 1365-1371
1999
7 Seiten, 8 Quellen
Article (Journal)
English
The formation mechanism of the hydrate phases in magnesium oxychloride cement^1
| British Library Online Contents | 1999
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| Online Contents | 1999