Abstract The aim of this work is using Bragg coherent X-ray diffraction imaging (BCDI) to study the calcite crystallization during carbonation of hydrated tricalcium silicate (C3S). Portland cement is a very complex synthesized product whose 50–70% mass is composed of C3S, which is the most important phase to produce calcium silicate hydrates and calcium hydroxide. Hence, its hydration contributes greatly to the hydration of cement and later to the carbonation of cement products when it reacts with CO2, often from the air, to form calcium carbonates. BCDI has emerged in the last decade as a promising high-resolution lens-less imaging approach for characterization of various samples. It has made significant progress with the development of X-ray sources and phase-retrieval algorithms. BCDI allows for imaging the whole three-dimensional structure of micro- and sub-micro- crystalline materials and can show the strain distribution at the nanometer spatial resolution. Results show that calcite crystallization follows a through-solution reaction and the growth model of the calcite crystal can be explained by using “phase domain” theory. During carbonation, calcite crystals grow by increasing the number of phase domains within them while the domain size remains at about 200–300 nm.

中文翻译：

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硅酸三钙水化过程中方解石结晶的相干衍射研究

摘要 这项工作的目的是使用布拉格相干 X 射线衍射成像 (BCDI) 来研究水合硅酸三钙 (C3S) 碳酸化过程中的方解石结晶。波特兰水泥是一种非常复杂的合成产品，其 50-70% 的质量由 C3S 组成，C3S 是生产硅酸钙水合物和氢氧化钙的最重要的相。因此，当它与通常来自空气的 CO2 反应形成碳酸钙时，它的水化对水泥的水化和随后的水泥产品的碳酸化有很大贡献。BCDI 在过去十年中已成为一种有前途的高分辨率无透镜成像方法，用于表征各种样品。随着X射线源和相位恢复算法的发展，它取得了重大进展。BCDI 允许对微晶和亚微晶材料的整个三维结构进行成像，并可以在纳米空间分辨率下显示应变分布。结果表明，方解石结晶遵循贯穿溶液反应，方解石晶体的生长模型可以用“相域”理论来解释。在碳酸化过程中，方解石晶体通过增加其中的相域数量而生长，而域尺寸保持在 200-300 nm 左右。