Abstract Historically, sparingly soluble mineral dissolution in aqueous solutions is measured at macroscopic scales, mostly by indirect methods that track the solution composition over times ranging from minutes to years. Relatively fewer measurements have been made of dissolution rates of highly soluble minerals and their variability at microscopic length scales and shorter times prior to the products precipitation. Here, we report in-situ, real-time measurements of the initial absolute dissolution rate of an extremely reactive mineral, cubic tricalcium aluminate (C3A), in pure water, by monitoring its surface retreat with nanometer resolution. The data reveal that C3A has an extremely fast dissolution rate within the instantaneous contact with water, in the range of (0.5 to 2) mmol·m−2·s−1 and several orders of magnitude greater than that of gypsum or calcite. Soon after that initial dissolution, nucleation and rapid growth of calcium aluminate hydrate would occur, leading to a dramatic decrease of the C3A dissolution rate by blocking its access to the solution. To our knowledge, this is the first time the real dissolution rate of C3A is measured in water, which is urgently needed for the fundamental modelling of the reaction mechanisms, kinetics, and microstructure development during cement hydration.

中文翻译：

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C3A在水中溶解的原位纳米级观察

摘要 从历史上看，水溶液中的微溶矿物溶解度是在宏观尺度上测量的，主要是通过间接方法来跟踪溶液成分，时间从几分钟到几年不等。对高溶解性矿物的溶解速率及其在微观长度尺度和产物沉淀前较短时间的可变性进行的测量相对较少。在这里，我们通过以纳米分辨率监测其表面后退，报告了在纯水中具有极高活性的矿物立方铝酸三钙 (C3A) 的初始绝对溶解速率的原位实时测量。数据表明，C3A在与水的瞬时接触范围内具有极快的溶解速率，范围为（0. 5 到 2) mmol·m-2·s-1 并且比石膏或方解石大几个数量级。在最初溶解后不久，水合铝酸钙会发生成核和快速生长，通过阻止其进入溶液导致 C3A 溶解速率急剧下降。据我们所知，这是第一次在水中测量 C3A 的真实溶解速率，这是对水泥水化过程中的反应机制、动力学和微观结构发展的基本建模所迫切需要的。