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In-situ XRD study of the temperature-dependent early hydration of calcium aluminate cement in a mix with calcite
Cement and Concrete Research ( IF 10.9 ) Pub Date : 2020-10-01 , DOI: 10.1016/j.cemconres.2020.106160
J. Goergens , T. Manninger , F. Goetz-Neunhoeffer

Abstract In the present work the hydration of white CAC, inert alumina-filler and CaCO3 was investigated at different temperatures with in-situ XRD. Experiments were performed at 10 °C, 23 °C, 40 °C and 60 °C. Overcoming or mitigating the phenomena of calcium aluminate hydrate conversion by adding reactive additives to calcium aluminate cement is often described in literature. When a sufficient amount of calcite is added, carbonate-AFm (monocarbonate and hemicarbonate) is expected to be the dominant hydrate phase. Calcite however, acts as an inert filler and barely influences the calcium aluminate hydration products at 10 °C. With rising temperature monocarbonate contents increase as well as the reaction rate of cement phases. At 60 °C minor amounts of C3AH6 precipitate during the early hydration. Special attention is given to the role of CAH10 and C2AHx during hydration. While CAH10 is dominant at 10 °C, C2AHx precipitates in a temperature range between 23 and 60 °C as a precursor phase for carbonate-AFm phases. These are not found at 10 °C, which is probably due to the lack of the precursor phase (C2AHx). The hydration of the mix at 10 °C with an initial addition of C2AHx shows that carbonate-AFm-phases can be precipitated in addition to CAH10 during the first 96 h.

中文翻译:

铝酸钙水泥与方解石混合物随温度变化的早期水化的原位 XRD 研究

摘要 在目前的工作中,用原位 XRD 研究了白色 CAC、惰性氧化铝填料和 CaCO3 在不同温度下的水合作用。实验在 10 °C、23 °C、40 °C 和 60 °C 下进行。文献中经常描述通过向铝酸钙水泥添加反应性添加剂来克服或减轻铝酸钙水合物转化现象。当加入足量的方解石时,预计碳酸盐-AFm(单碳酸盐和半碳酸盐)将成为主要的水合物相。然而,方解石作为惰性填料,在 10 °C 时几乎不影响铝酸钙水合产物。随着温度升高,单碳酸盐含量增加以及水泥相的反应速率增加。在 60 °C 时,在早期水合过程中有少量 C3AH6 沉淀。特别注意 CAH10 和 C2AHx 在水合作用过程中的作用。虽然 CAH10 在 10 °C 时占主导地位,但 C2AHx 在 23 至 60 °C 的温度范围内沉淀,作为碳酸盐-AFm 相的前体相。这些在 10 °C 下未发现,这可能是由于缺少前体相 (C2AHx)。混合物在 10 °C 下与初始添加 C2AHx 的水合表明,在最初的 96 小时内,除了 CAH10 之外,碳酸盐-AFm 相也可以沉淀。
更新日期:2020-10-01
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