Mechanisms of Stratlingite Formation in High Alumina Cement-Siliceous Material Systems

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Title: Mechanisms of Stratlingite Formation in High Alumina Cement-Siliceous Material Systems

Author(s): Y. Fu, J. Ding, and J. J. Beaudoin

Publication: Special Publication

Volume: 154

Issue:

Appears on pages(s): 461-472

Keywords: blast furnace slag; C 3AH 6; fly ash; high-alumina cements; pH; pozzolan cements; silica fume; sodium silicates; sodium sulfates; X-ray diffraction; Materials Research

Date: 5/1/1995

Abstract:
Mechanisms of stratlingite (C 2ASH 8) formation in high-alumina cement (HAC)-siliceous material systems were investigated. Different siliceous materials (silica fume, fly ash, ground granulated blast furnace slag) and chemical admixtures (sodium silicate, sodium sulfate) were employed. Reactions between CAH 10 or C 2AH 8 and dissolved silica occur. Acceleration of silica dissolution by addition of chemical admixtures promotes the formation of stratlingite. The pH value of the HAC-siliceous materials system was also studied. The intrinsic relationship between the pH value and stratlingite formation is discussed in this paper. Mechanisms of stratlingite formation in preference to hydrogarnet (C 3AH 6) in HAC products are postulated. A method for prevention of strength reduction of HAC products due to the conversion of thermodynamically unstable hexagonal calcium aluminates to cubic hydrogarnet is described.