Stability in the system CaO–Al&lt;SUB&gt;2&lt;/SUB&gt;O&lt;SUB&gt;3&lt;/SUB&gt;–H&lt;SUB&gt;2&lt;/SUB&gt;O

Lothenbach, Barbara; Pelletier-Chaignat, Laure; Winnefeld, Frank

doi:10.1016/j.cemconres.2012.09.002

Stability in the system CaO–Al₂O₃–H₂O

Lothenbach B, Pelletier-Chaignat L & Winnefeld F

Citation

Lothenbach, B., Pelletier-Chaignat, L., & Winnefeld, F. (2012). Stability in the system CaO–Al₂O₃–H₂O. Cement and Concrete Research, 42(12), 1621-1634. https://doi.org/10.1016/j.cemconres.2012.09.002

Persistent URL https://www.dora.lib4ri.ch/empa/islandora/object/empa:5447

The solubility of AH₃, CAH₁₀, C₂AH_7.5, and C₃AH₆ was determined experimentally at 7 to 40 °C and up to 570 days. During the reaction of CA, at 20 °C and above initially C₂AH_7.5 formed which was unstable in the long-term. The solubility products calculated indicate that the solubilities of CAH₁₀, C₂AH_7.5 and C₄AH₁₉ increase with temperature while the solubility of C₃AH₆ decreases. Thus at temperatures above 20 °C, C₃AH₆ is stable, while at lower temperature also CAH₁₀ and C₄AH₁₉ are stable, depending on the C/A ratio. At early hydration times, CAH₁₀ can be stable initially at 30 °C and above, as the formation of amorphous AH₃ stabilises CAH₁₀ with respect to C₃AH₆ + 2AH₃. With time, as the solubility AH₃ decreases due to the formation of microcrystalline AH₃, CAH₁₀ becomes unstable at 20 °C and above.