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Evolution of ettringite in presence of carbonate and silicate ions
The main objective of this work was to study the evolution of ettringite when in contact with a solution containing carbonate and silicate ions. Ettringite was synthesised and put in contact with 3 types of saturated solutions: a) CaCO3 and silica gel saturated solution; b) MgCO3 and silica gel saturated solution and c) C-S-H gel plus portlandite and CaCO3 saturated solution. The temperature of the experiment was 4 +/- 2 deg C. At different ages the samples were studied by: FTIR, XRD, NMR, and SEM/EDX. Ettringite evolves with time, reacting with carbonates and silicates and decomposing to poorly crystallised products when it is in the contact with solutions a) and b). Ettringite decomposition rate is much higher when it is in contact with saturated magnesium carbonate solution (b) than when in contact with the solution a). After 90 days of exposure in solution b) ettringite decomposition starts, followed by reorganization of the atoms giving place to a semi-stable poorly crystallised compound. However 130 days are necassary for ettringite decomposition in solution a). Ettringite in contact with solution c) evolves more slowly and it almost remains unchanged after 380 days of treatment. Ca(OH)2 formed in the C3S and C2S hydration retards ettringite decompostion.
Evolution of ettringite in presence of carbonate and silicate ions
The main objective of this work was to study the evolution of ettringite when in contact with a solution containing carbonate and silicate ions. Ettringite was synthesised and put in contact with 3 types of saturated solutions: a) CaCO3 and silica gel saturated solution; b) MgCO3 and silica gel saturated solution and c) C-S-H gel plus portlandite and CaCO3 saturated solution. The temperature of the experiment was 4 +/- 2 deg C. At different ages the samples were studied by: FTIR, XRD, NMR, and SEM/EDX. Ettringite evolves with time, reacting with carbonates and silicates and decomposing to poorly crystallised products when it is in the contact with solutions a) and b). Ettringite decomposition rate is much higher when it is in contact with saturated magnesium carbonate solution (b) than when in contact with the solution a). After 90 days of exposure in solution b) ettringite decomposition starts, followed by reorganization of the atoms giving place to a semi-stable poorly crystallised compound. However 130 days are necassary for ettringite decomposition in solution a). Ettringite in contact with solution c) evolves more slowly and it almost remains unchanged after 380 days of treatment. Ca(OH)2 formed in the C3S and C2S hydration retards ettringite decompostion.
Evolution of ettringite in presence of carbonate and silicate ions
Entwicklung von Ettringit in Gegenwart von Carbonat- und Silicationen
Pajares, I. (Autor:in) / Martinez-Ramirez, S. (Autor:in) / Blanco-Varela, M.T. (Autor:in)
2002
11 Seiten, 6 Bilder, 16 Quellen
Aufsatz (Konferenz)
Datenträger
Englisch
Calciumcarbonat , Calciumhydroxid , CSH (Calciumsilicathydrat) , Dicalciumsilicat , energiedispersive Röntgenspektrometrie , Ettringit , feste Lösung , FT-IR-Spektroskopie , gesättigte Lösung , Ion , Kieselgel , Magnesiumcarbonat , magnetische Kernresonanz , Portlandzement , Rasterelektronenmikroskop , Röntgendiffraktion , Temperatur , Thaumasit , Tricalciumsilicat , Zersetzung
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