A platform for research: civil engineering, architecture and urbanism
A platform for research: civil engineering, architecture and urbanism
Thaumsite direct, woodfordite and other possible formation routes
Two main formation routes for thaumasite exist below 15 deg C. One is the direct route from C-S-H reacting with appropriate carbonate, sulfate, Ca(2+) ions and excess water. The other route is the woodfordite route from ettringite reacting with C-S-H, carbonate, Ca(2+) ions and excess water, in which thaumasilsite arises through the intermediate formation of the solid solution woodfordite. The woodfordite route for thaumasite formation appears to be relatively quicker (although still slow) than the direct route, presumably because with the former the ettringite already has the octahedral (M(OH)6) units that can facilitate the critical change from (Al(OH)6)(3-) to (Si(OH)6)(2-) groupings. Both routes are mutually dependent on each other. The presence of magnesium salts can modify the path to thaumasite formation. High pressure might be able to stabilise (Si(OH)6)(2-) groupings and allow thaumasite to become formed above 15 deg C. This possibility is dicussed.
Thaumsite direct, woodfordite and other possible formation routes
Two main formation routes for thaumasite exist below 15 deg C. One is the direct route from C-S-H reacting with appropriate carbonate, sulfate, Ca(2+) ions and excess water. The other route is the woodfordite route from ettringite reacting with C-S-H, carbonate, Ca(2+) ions and excess water, in which thaumasilsite arises through the intermediate formation of the solid solution woodfordite. The woodfordite route for thaumasite formation appears to be relatively quicker (although still slow) than the direct route, presumably because with the former the ettringite already has the octahedral (M(OH)6) units that can facilitate the critical change from (Al(OH)6)(3-) to (Si(OH)6)(2-) groupings. Both routes are mutually dependent on each other. The presence of magnesium salts can modify the path to thaumasite formation. High pressure might be able to stabilise (Si(OH)6)(2-) groupings and allow thaumasite to become formed above 15 deg C. This possibility is dicussed.
Thaumsite direct, woodfordite and other possible formation routes
Thaumasit - direkte Bildung, über Woodfordit und andere mögliche Bildungswege
Bensted, J. (author)
2002
8 Seiten, 1 Bild, 1 Tabelle, 16 Quellen
Conference paper
Storage medium
English
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