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.

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  • Accession Number: 01597430
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Apr 13 2016 4:19PM