Abstract The carbonation of portlandite, calcium silicate hydrate (C-S-H), and ettringite was investigated at 57% RH and 91% RH using X-ray diffraction, thermogravimetric analysis, infrared spectroscopy, and the phenolphthalein spray test. The experiments show that the carbonation of portlandite, ettringite, and C-S-H with Ca/Si = 0.7 is significantly faster at 91% RH than at 57% RH. Little effect of RH is observed for C-S-H with higher Ca/Si. Portlandite and C-S-H with Ca/Si = 0.7 carbonate only partially at 57% RH; complete carbonation is observed if the relative humidity is increased to 91% RH. In contrast, the carbonation of C-S-H with Ca/Si = 1.2 and 1.5 is complete at both relative humidities. The carbonation rate of C-S-H decreases with decreasing Ca/Si ratio, both at 57% and 91%RH. Carbonation at 57% RH promotes the formation of vaterite and aragonite over calcite; the precipitation of amorphous calcium carbonate is observed for C-S-H with Ca/Si = 0.7.

中文翻译：

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相对湿度对硅酸盐、硅酸钙水合物和钙矾石碳化率的影响

摘要 使用 X 射线衍射、热重分析、红外光谱和酚酞喷雾试验研究了在 57% RH 和 91% RH 下碳酸钙、水合硅酸钙 (CSH) 和钙矾石的碳酸化。实验表明，在 Ca/Si = 0.7 的情况下，钙钛矿、钙矾石和 CSH 的碳化在 91% RH 下比在 57% RH 下明显更快。对于具有较高 Ca/Si 的 CSH，几乎没有观察到 RH 的影响。Ca/Si = 0.7 碳酸盐的硅酸盐和 CSH 在 57% RH 下仅部分；如果相对湿度增加到 91% RH，则观察到完全碳酸化。相比之下，Ca/Si = 1.2 和 1.5 的 CSH 碳化在两种相对湿度下都完成。在 57% 和 91%RH 下，CSH 的碳化率随着 Ca/Si 比的降低而降低。57% RH 的碳化促进了球霰石和文石在方解石上的形成；对于 Ca/Si = 0.7 的 CSH，观察到无定形碳酸钙的沉淀。