Compatibility of Hydrogarnet, Ca₃Al₂(SiO₄)x(OH)4(3 - X), with Sulfate and Carbonate-Bearing Cement Phases: 5-85 °C
The stable existence of hydrogarnet in Portland cement compositions cured at temperatures below 55 °C has long been predicted from application of equilibrium thermodynamics. However hydrogarnet is not often reported in hydrated commercial Portland cements. The substitutions (SO4-CO3-OH) in AFm have previously been shown to stabilise AFm to higher temperatures and raise the temperature at which AFm converts to Si-free hydrogarnet, C3AH6. But unanswered question remains about the compatibility of AFm and AFm solid solutions with Si-substituted hydrogarnet, Ca3Al2(SiO4)x(OH)4(3 - X). Phase relations of C3AH6 and Ca3Al2 (SiO4)x(OH)4(3 - X) at sulfate and carbonate activities conditioned respectively by (gypsum and SO4-AFt) and (calcite and CO3-AFt) have been determined experimentally in the range 5-85 °C. The results confirm the instability of Si-free hydrogarnet with carbonate and sulfate-bearing cement phases, but do indicate that a range of silica-substituted hydrogarnet solid solutions are stable under conditions likely to be encountered in blended cement systems.
M. U. Okoronkwo and F. P. Glasser, "Compatibility of Hydrogarnet, Ca₃Al₂(SiO₄)x(OH)4(3 - X), with Sulfate and Carbonate-Bearing Cement Phases: 5-85 °C," Cement and Concrete Research, vol. 83, pp. 86-96, Elsevier Ltd, May 2016.
The definitive version is available at https://doi.org/10.1016/j.cemconres.2016.01.013
Chemical and Biochemical Engineering
Keywords and Phrases
Carbonate (D); Hydrogarnet (D); Kinetics (A); Stability(C); Sulfate (D)
International Standard Serial Number (ISSN)
Article - Journal
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