On the structure and the formation of the structure of C-S-H phases in future cementitious binders

混凝土是我们这个时代主要的建筑材料。在全球范围内，水泥是混凝土中最重要的粘合剂。但是，水泥的生产与大量的二氧化碳排放有关。为了减少这些排放，目前世界各地都在研究替代方案。从中期来看，复合材料（SCMs）部分替代波特兰水泥熟料是一个不错的选择。硅酸盐（复合）水泥与水的反应导致纳米级硅酸盐水合钙（C-S-H）相的形成，这是硬化混凝土中的主要水合相。这些相决定了混凝土的大部分宏观特性。C-S-H的结构和结构的形成目前还不是很清楚，这是本提案的主要主题。了解这两个参数对于新水泥的成功应用至关重要，也为这些粘合剂的新应用铺平了道路。基于两位申请者的合作，有关结构形成的新方法将从基础科学转移到工程。这是更重要的，因为发现晶体的形成不仅限于单体之间的附着。前驱相的聚集也是结晶（非经典结晶）的一种潜在途径。这为混凝土宏观性能的设计开辟了新的视角。本文系统地分为五个部分。在第一部分（实际体系）中，研究了不同粒径水泥中C-S-H相的形成条件。第二部分对这些相进行了纯合成（模型系统）。在第三部分中，主要通过分析超离心和动态光散射的方法研究了潜在前驱相结构的形成和外来离子的影响。如果潜在的前驱相确实存在于胶凝体系中，这是中心相关性，因此是非经典结晶理论的进一步指示。第四部分主要研究了C-S-H相的结构（晶格、溶解度），特别关注了SCMs引入的外源离子（浓度和种类）的影响。这里对合成和方法都有很高的要求。因此，光谱学、电子显微镜以及同步辐射衍射将互补进行。最后对骨料与水泥石界面过渡区进行了研究。在这里，我们期望建立一座从基础科学到具体的桥梁。该项目的结果将进行跨学科讨论，并在适当的期刊上发表。为了进一步了解水泥最重要的反应产物的结构和结构的形成是本提案的主要目的。

Concrete is the main building material in our time. At a global level, cement is the most important binder within the concrete. But the manufacture of cement is associated with a strong emission of CO2. In order to reduce these emissions, alternatives are currently worked out worldwide. In a medium-term, a good alternative is to partly substitute Portland cement clinker by composite materials (SCMs). The reaction of Portland(composite) cements with water leads to the formation of nanoscaled Calcium-Silicate-Hydrate (C-S-H) phases -the main hydrate phases in hardened concrete. These phases are responsible for most of all macroscopic properties of concrete. Both structure and formation of structure of C-S-H are currently not sufficiently known, and are the main subjects of the proposal. It is essential to know both parameters for the successful application of the new cements and also to pave the way for these binders for new applications. New approaches regarding structure formation will be transferred from the fundamental science to engineering based on the collaboration of the two applicants. This is even more important, since it is found that crystal formation is not restricted only to monomer-monomer attachment. Also the aggregation of precursor phases is a potential route for crystallization (non-classical crystallization). This opens new perspectives in the design of the macroscopic properties of concrete.The proposal is systematically subdivided into five parts. The conditions of formation of C-S-H phases is investigated within cements with different SCMs during the first part (real system). In the second part, these phases are synthesized in a pure way (model system). Within the third part, the formation of the structure via potential precursor phases and the impact of foreign ions is mainly investigated by means of Analytical Ultracentrifugation and Dynamic Light Scattering. Here it is of central relevance if potential precursor phases do exist in cementitious systems, and thus are further indications for the non-classical crystallization theory. In the fourth part, the investigation of the structure (crystal lattice, solubility) of these C-S-H phases is mainly focused with special attention on the impact of the foreign ions introduced by SCMs (concentration and kind). Here high requirements have to meet regarding synthesis and methods. Thus, spectroscopy, electron microscopy as well as diffraction with synchrotron radiation will complementary be performed. The interfacial transition zone between aggregates and cement stone is investigated in the last part. Here we anticipate to build a bridge from fundamental science to concrete. The results of the project will be interdisciplinary discussed and published in appropriate journals. To get a step forward in understanding the structure and the formation of the structure of the most important reaction product of cement is the main aim of the proposal.