Mechanism of ettringite and monosulphate formation

✍ Scribed by J. Havlica; S. Sahu

• Book ID: 103000740
• Publisher: Elsevier Science
• Year: 1992
• Tongue: English
• Weight: 508 KB
• Volume: 22
• Category: Article
• ISSN: 0008-8846
• DOI: 10.1016/0008-8846(92)90019-r

✦ Synopsis

The kinetics of the hydration process of the sulphoaluminate phase Ca4(A16012)(SO 4) in the presence of calcium hydroxide and gypsum were studied by differential calorimetry, optical microscope and X-ray phase analysis. The f'trst period of reaction is characterized by the presence of ettringite even in the case of stoichiometric composition of monosulphate. The liquid interlayer on the surface of the sulphoaluminate phase plays an important role in the kinetics of hydration. The solubility of the sulphoaluminate phase is higher in the lower pH values of the surrounding liquid phase which causes acceleration of the hydration process.

Ettringite was created at a certain distance (8i) from the surface of the sulphoaluminate phase. This thickness 8 i depends on the content of a dissoluting Ca4(AI6012)(SO 4) phase.