A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Metaettringite, a decomposition product of ettringite
Dehydroxylation of ettringite in an atmosphere of constant partial water vapour pressure (30-400 Torr) and controlled temperature (55-95 degree C) yields an X-ray amorphous product containing 11-13 H2O per ettringite formula unit. The X-ray amorphous product does, however, give electron diffraction patterns similar to those of ettringite but with a considerably reduced from (similar to)1.123 nm (ettringite) to 0.85 nm in the partially dehydroxylated product, termed metaettringite. The structure of metaettringite is closely related to that of fleischerite, Pb3Ge((OH) 6)(SO4)2 dot 3H2O and the isostructural despujolsite, Ca3MnIV(SO 4) 2(OH)6 dot 3H2O. These minerals contain columnar units. The columnar structure is like that of ettringite but with closer packing of columns in the a direction, resembling metaettringite. The mechanism of collapse of ettringite to metaettringite, involving loss of water and motion of columns, cannot be achieved without scissoring and possibly rotation of individual columns; this and other defect-producing mechanisms result in loss of crystallinity of the metaettringite product.
Metaettringite, a decomposition product of ettringite
Dehydroxylation of ettringite in an atmosphere of constant partial water vapour pressure (30-400 Torr) and controlled temperature (55-95 degree C) yields an X-ray amorphous product containing 11-13 H2O per ettringite formula unit. The X-ray amorphous product does, however, give electron diffraction patterns similar to those of ettringite but with a considerably reduced from (similar to)1.123 nm (ettringite) to 0.85 nm in the partially dehydroxylated product, termed metaettringite. The structure of metaettringite is closely related to that of fleischerite, Pb3Ge((OH) 6)(SO4)2 dot 3H2O and the isostructural despujolsite, Ca3MnIV(SO 4) 2(OH)6 dot 3H2O. These minerals contain columnar units. The columnar structure is like that of ettringite but with closer packing of columns in the a direction, resembling metaettringite. The mechanism of collapse of ettringite to metaettringite, involving loss of water and motion of columns, cannot be achieved without scissoring and possibly rotation of individual columns; this and other defect-producing mechanisms result in loss of crystallinity of the metaettringite product.
Metaettringite, a decomposition product of ettringite
Zhou, Q. (author) / Lachowski, E.E. (author) / Glasser, F.P. (author)
Cement and Concrete Research ; 34 ; 703-710
2004
8 Seiten, 13 Quellen
Article (Journal)
English
Metaettringite, a decomposition product of ettringite
| Online Contents | 2004
Metaettringite, a decomposition product of ettringite
| British Library Online Contents | 2004
Ettringite decomposition in the presence of barium carbonate
| Tema Archive | 2013
| British Library Online Contents | 2003
Ettringite decomposition in the presence of barium carbonate
| Online Contents | 2013