The reasons for the start and end of the induction period of cement hydration remain topic of controversy. One long-standing hypothesis is that a thin metastable hydrate forming on the surface of cement grains significantly reduces the particle dissolution rate; the eventual disappearance of this layer re-establishes higher dissolution rates at the beginning of the acceleration period. However, the importance, or even the existence, of this metastable layer has been questioned because it cannot be directly detected in most experiments. In this work, a combined analysis using nano-tomography and nano-X-ray fluorescence makes the direct imaging of early hydration products possible. These novel X-ray imaging techniques provide quantitative measurements of 3D structure, chemical composition, and mass density of the hydration products during the induction period. This work does not observe a low density product on the surface of the particle, but does provide insights into the formation of etch pits and the subsequent hydration products that fill them.

中文翻译：

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在 C 3 s 水合诱导期直接测量 3d 结构、化学和质量密度

水泥水化诱导期的开始和结束的原因仍然存在争议。一个长期存在的假设是，在水泥颗粒表面形成的亚稳态薄水合物显着降低了颗粒溶解速率；该层的最终消失在加速期开始时重新建立更高的溶解率。然而，这个亚稳态层的重要性，甚至其存在性一直受到质疑，因为它在大多数实验中无法直接检测到。在这项工作中，使用纳米断层扫描和纳米 X 射线荧光的组合分析使早期水合产物的直接成像成为可能。这些新颖的 X 射线成像技术提供 3D 结构、化学成分、和诱导期水化产物的质量密度。这项工作没有观察到颗粒表面的低密度产物，但确实提供了对蚀刻坑的形成和随后填充它们的水合产物的见解。