Phase identification during early and middle hydration of tricalciumsilicate (Ca3SiO5)

✍ Scribed by R. Melzer; E. Eberhard

• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 886 KB
• Volume: 19
• Category: Article
• ISSN: 0008-8846
• DOI: 10.1016/0008-8846(89)90030-6

✦ Synopsis

The hydration reaction of tricalciumsilicate was observed during the first 14 days with electron microscopic methods. This investigation aimed mainly at the identification of calcium-silicate-hydrate (CSH) by TEM diffraction techniques. By this method crystalline structural units in CSH gel and four crystalline CSH phases could be identified. These phases coexist side by side from 8 hours after the beginning of the hydration until the end of the observation period. Their electron diffraction patterns look similar to that of the llA-tobermorite but the d-spacings vary slightly. Nevertheless, the main reflections were accordingly indexed to determine lattice constants. The crystalline phases are designated as c~-, {3-, y-und 8-CSH. As a further reaction product, a sheet-like epitaxial intergrowth of different CSH phases and also portlandite parallel to the basal plane was observed. These layers, about 10 to I00 nm thick, are rotated around the c-axis because of small differences in the lattice constants. An interpretation of the hydration process of tricalciumsilicate is given, because of the appearance of new phases.