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

未来胶凝材料中C-S-H相的结构和形成

• 批准号: 401097244
• 负责人: Professor Dr. Helmut Cölfen (†)
• 金额: --
• 依托单位: Arbeitsgruppe Physikalische Chemie (AG Cölfen)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2018
• 资助国家: 德国
• 起止时间: 2017-12-31 至 2022-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/401097244?language=en
• 关键词: structure; formation; phases; future; cementitious

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.

混凝土是我们这个时代的主要建筑材料。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，一个好的替代办法是用复合材料部分替代波特兰水泥熟料。波特兰（复合）水泥与水反应导致形成纳米级硅酸钙-水化钙（C-S-H）相-硬化混凝土中的主要水化相。这些相是混凝土的大部分宏观性能的原因。C-S-H的结构和结构的形成目前还不完全清楚，这是该提案的主要主题。必须了解成功应用新水泥的两个参数，并为这些粘合剂的新应用铺平道路。基于两个申请人的合作，关于结构形成的新方法将从基础科学转移到工程学。这甚至更重要，因为发现晶体形成不仅限于单体-单体连接。前体相的聚集也是结晶（非经典结晶）的潜在途径。这为混凝土宏观性能的设计开辟了新的视角。在第一部分（真实的体系）中，研究了具有不同SCMs的水泥中C-S-H相的形成条件。在第二部分中，这些阶段是在一个纯粹的方式（模型系统）综合。在第三部分中，通过潜在的前体相的结构的形成和外来离子的影响，主要是通过分析超离心和动态光散射研究。在这里，如果潜在的前体相确实存在于胶凝体系中，这是至关重要的，因此是非经典结晶理论的进一步迹象。在第四部分中，这些C-S-H相的结构（晶格，溶解度）的调查主要集中在特别注意的影响，引入的外来离子（浓度和种类）的SCM。在此，必须满足关于合成和方法的高要求。因此，光谱学，电子显微镜以及衍射与同步辐射将互补进行。最后对集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混凝土的桥梁。该项目的结果将进行跨学科讨论，并在适当的期刊上发表。该提案的主要目的是在了解水泥最重要的反应产物的结构和结构形成方面向前迈进一步。