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Semi-dry natural carbonation at different relative humidities: Degree of carbonation and reaction kinetics of calcium hydrates in cement paste
Cement and Concrete Research ( IF 10.9 ) Pub Date : 2024-12-30 , DOI: 10.1016/j.cemconres.2024.107777
Naohiko Saeki, Ryo Kurihara, Takahiro Ohkubo, Atsushi Teramoto, Yuya Suda, Ryoma Kitagaki, Ippei Maruyama

This study investigated semi-dry carbonation at different relative humidities (RH) under atmospheric CO2 concentrations to determine the effect of RH on the degree of carbonation (DoC) and reaction rates. The carbonation kinetics of each calcium-containing hydrate exhibited an initial rapid chemical-reaction-limited stage, followed by a significantly slower stage. DoC values plateaued after 200 days of carbonation, reaching 78 % at 95 % RH and 34 % at 33 % RH, aligning with EN 16757 values for sheltered outdoor and indoor environments, respectively. When the samples reached a stable DoC at a given RH, further carbonation occurred upon exposure to higher RH, implying that the DoC was governed by the highest RH to which the samples had been exposed. The phase assemblage was also affected, approaching thermodynamic equilibrium at higher RH but deviating at lower RH due to the formation of local equilibria and the presence of metastable phases.

中文翻译:


不同相对湿度下的半干自然碳化:水泥浆中水合钙的碳化程度和反应动力学



本研究调查了大气 CO2 浓度下不同相对湿度 (RH) 下的半干碳化,以确定 RH 对碳化程度 (DoC) 和反应速率的影响。每种含钙水合物的碳酸化动力学都表现出初始的快速化学反应限制阶段,然后是明显较慢的阶段。碳化 200 天后,DoC 值趋于稳定,在 95 % RH 时达到 78%,在 33 % RH 时达到 34%,分别与 EN 16757 针对遮蔽室外和室内环境的值一致。当样品在给定 RH 下达到稳定的 DoC 时,暴露于更高的 RH 时会发生进一步的碳化,这意味着 DoC 受样品暴露的最高 RH 控制。相组合也受到影响,在较高 RH 时接近热力学平衡,但由于局部平衡的形成和亚稳相的存在,在较低 RH 时偏离。
更新日期:2024-12-30
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