Compatibility of hydrogarnet, Ca{sub 3}Al{sub 2}(SiO{sub 4}){sub x}(OH){sub 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 (SO{sub 4}–CO{sub 3}–OH)...
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Published in | Cement and concrete research Vol. 83 |
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Main Authors | , , |
Format | Journal Article |
Language | English |
Published |
United States
15.05.2016
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Subjects | |
Online Access | Get full text |
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Summary: | 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 (SO{sub 4}–CO{sub 3}–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, C{sub 3}AH{sub 6}. But unanswered question remains about the compatibility of AFm and AFm solid solutions with Si-substituted hydrogarnet, Ca{sub 3}Al{sub 2}(SiO{sub 4}){sub x}(OH){sub 4(3} {sub −} {sub x)}. Phase relations of C{sub 3}AH{sub 6} and Ca{sub 3}Al{sub 2}(SiO{sub 4}){sub x}(OH){sub 4(3} {sub −} {sub x)} at sulfate and carbonate activities conditioned respectively by (gypsum and SO{sub 4}-AFt) and (calcite and CO{sub 3}-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. |
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ISSN: | 0008-8846 1873-3948 |
DOI: | 10.1016/J.CEMCONRES.2016.01.013 |