Abstract Celitement is a new type of cement that is based on hydraulic calcium-hydrosilicate (hCHS). It is produced by mechanochemical activation of Calcium-Silicate-Hydrates (C-S-H) in a grinding process. Due to the lack of typical clinker minerals, its CaO/SiO2 (C/S) ratio can be minimized from above 3 (as in Ordinary Portland Cement) down to 1, which significantly reduces the amount of CO2 released during processing. The reaction kinetics of hCHS differs from that of classical clinker phases due to the presence of highly reactive silicate species, which involve silanol groups instead of pure calcium silicates and aluminates and aluminoferrites. In contrast to Portland cement, no calcium hydroxide is formed during hydration, which otherwise regulates the Ca concentration. Without the buffering role of Ca(OH)2 the concentration of the dissolved species c(Ca2+) and c(SiO44−) and the corresponding pH must be controlled to ensure a reproducible reaction. Pure hCHS reacts isochemically with water, resulting in a C-S-H phase with the same chemical composition as a single hydration product, with a homogeneous distribution of the main elements Ca and Si throughout the sample. Here we study via nanoindentation tests, the mechanical properties of two different types of hardened pastes made out of Celitement (C/S = 1.28), with varying amounts of hCHS and variable water to cement ratio. We couple nanoindentation grids with Raman mappings to link the nanoscale mechanical properties to individual microstructural components, yielding in-depth insight into the mechanics of the mineralogical phases constituting the hardened cement paste. We show that we can identify in hardened Celitement paste both fresh C-S-H with varying density, and C-S-H from the raw material using their specific Raman spectra, while simultaneously measuring their mechanical properties. Albeit not suitable for phase identification, supplemental EDX measurements provide valuable information about the distribution of alkalis, thus further helping to understand the reaction pattern of hCHS.

中文翻译：

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结合拉曼和纳米压痕测量的水合氢硅酸钙的化学机械表征

摘要 Celitement是一种以水硬性硅酸钙（hCHS）为基础的新型水泥。它是通过在研磨过程中对硅酸钙 (CSH) 进行机械化学活化而产生的。由于缺乏典型的熟料矿物，其 CaO/SiO2 (C/S) 比可以从高于 3（如普通硅酸盐水泥）降至 1，从而显着减少加工过程中释放的 CO2 量。由于存在高反应性硅酸盐物质，hCHS 的反应动力学不同于经典熟料相，其涉及硅烷醇基团而不是纯硅酸钙、铝酸盐和铝铁酸盐。与波特兰水泥相反，在水化过程中不会形成氢氧化钙，否则会调节 Ca 浓度。如果没有 Ca(OH)2 的缓冲作用，必须控制溶解物质 c(Ca2+) 和 c(SiO44-) 的浓度以及相应的 pH 值，以确保反应的重现性。纯 hCHS 与水发生等化学反应，产生与单一水合产物化学成分相同的 CSH 相，主要元素 Ca 和 Si 均匀分布在整个样品中。在这里，我们通过纳米压痕测试研究了两种不同类型的由 Celitement (C/S = 1.28) 制成的硬化浆料的机械性能，具有不同数量的 hCHS 和可变的水水泥比。我们将纳米压痕网格与拉曼映射相结合，将纳米级机械性能与单个微结构组件联系起来，深入了解构成硬化水泥浆的矿物相的力学。我们表明，我们可以在硬化的 Celitement 糊状物中识别具有不同密度的新鲜 CSH 和来自原材料的 CSH，使用它们的特定拉曼光谱，同时测量它们的机械性能。尽管不适合相识别，但补充 EDX 测量提供了有关碱分布的宝贵信息，从而进一步帮助了解 hCHS 的反应模式。