Study of the system CaOSiO2CO2H2O in relation to scawtite under hydrothermal conditions

✍ Scribed by I. Kaprálik; L. Števula; J. Petrovič; F. Hanic

• Publisher: Elsevier Science
• Year: 1984
• Tongue: English
• Weight: 368 KB
• Volume: 14
• Category: Article
• ISSN: 0008-8846
• DOI: 10.1016/0008-8846(84)90013-9

✦ Synopsis

Hydrothermal studies showed the location of scawtite in the narrow internal tetrahedron foshagite-xonotlite-CO2-H20 of the system CaO-SiO2-C02-H20 and its compatibility with the calcium silicate hydrates in the 4-phase assemblages. The phase assemblages in this region involve scawtite, foshagite, xonotlite, tobermorite, hillebrandite, calcite and silica. The carbonation series of the 4-phase assemblages were determined in the sections C4S3-C02-H20 (C4S3 = 4Ca0.3Si02), C7S6-C02-H20 and C6S6-C02-H20 at 473 K and saturated steam pressure in dependence on the CO 2 content. The carbonating influence of CO 2 takes place in the volume of the CaO-SiO2-CO2-H20 system,up to the CO 2 concentration limited by the calcite-silica-H20 triangle. Above this CO 2 content, carbon dioxide appears in a gaseous form together with gaseous H20 in the 4-phase assemblage calcite-silica-CO2H20. The instability of scawtite under the CO 2 excess (C02/C7S 6 > I) is influenced by its structural arrangement. The present channels enable penetration of CO 2 molecules into the structure and formation of carbonated phases.