标题： 接触点几何控制波特兰水泥-石灰石混合物在静止时的结构形成 显示英文标题

标题： Contact point geometry governs structural build-up at rest in Portland cement-limestone blends

摘要： 早期新鲜水泥浆的硬化在浇筑和3D打印过程中对形状和稳定性起着关键作用。 在波特兰水泥体系中，这种现象源于硅酸钙水合物（C-S-H）的形成，这使得颗粒间的接触变硬。 然而，粉末特性如颗粒尺寸和形态的作用仍然不明确。 在这里，我们通过将波特兰水泥与粗粒或细粒石灰石混合来改变细度和颗粒形状，利用C-S-H在石灰石表面成核的亲和性。 通过量热法和流变仪，我们将形成的水化产物量与刚度的增加联系起来，并表明通过C-S-H形成进行接触硬化的机制在添加石灰石后保持不变。 然而，不同混合物的硬化速率有所不同。 我们发现这些速率与一个表征长度尺度相关，该尺度捕捉了颗粒尺寸和形状。 这些结果表明，早期硬化不仅取决于形成的水化产物的数量，还取决于这些产物形成的接触几何结构，为理解更复杂的系统（如石灰石煅烧粘土水泥）提供了框架。 显示英文摘要

摘要： The early stiffening of fresh cement paste plays a key role in shaping and stability during casting and 3D printing. In Portland cement systems, this phenomenon arises from the formation of calcium-silicate-hydrate (C-S-H), which stiffens grain-to-grain contacts. However, the role of powder characteristics such as particle size and morphology remains poorly understood. Here, we vary the fineness and grain shape by blending Portland cement with either coarse or fine limestone, leveraging the affinity of C-S-H to nucleate on limestone surfaces. By coupling calorimetry and rheometry, we relate the amount of formed hydration products to the increase in stiffness, and show that the mechanism of contact stiffening through C-S-H formation remains unchanged with limestone addition. Nevertheless, the rate of stiffening varies across blends. We find that these rates correlate with a characteristic length scale that captures particle size and shape. These results demonstrate that early stiffening depends not only on the amount of hydration products formed, but also on the geometry of the contacts where these products form, offering a framework for understanding more complex systems such as limestone-calcined clay cements.