Investigation and modelling of alite hydration

阿利特水合作用的研究和建模

• 批准号: 267102159
• 负责人: Privatdozent Dr.-Ing. Frank Bellmann
• 金额: --
• 依托单位: F. A. Finger-Institut für Baustoffkunde
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2014
• 资助国家: 德国
• 起止时间: 2013-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/267102159?language=en
• 关键词: Investigation; modelling; alite; hydration

More than 4 billion tons of cement are currently produced and consumed each year. The process contributes approximately 8% to the total man-made carbon dioxide emissions and is associated to a high consumption of primary energy. Cement is used for the production of concrete, which is the most important material in construction.Compared to the importance of the material, the knowledge about the chemical reactions during hardening is only poorly developed. Understanding of the mechanisms governing the hydration would enable the reduction of environmental impacts and the development of high performance binders and concretes.The previous project provided highly important contributions to the understanding of the basic mechanisms of tricalcium silicate hydration in the absence of foreign ions. It was proved for the first time that the kinetics in the first hours depends purely on the precipitation rate of C-S-H. Beyond this qualitative demonstration, quantitative data for relevant parameters such as interfacial rates, surface areas, degree of reaction and solution composition were analyzed and fed to a simple and robust kinetic model. This model can quantitatively capture the hydration of tricalcium silicate in the absence of foreign ions and the results of the computations are confirmed by experimental data. The methods used for model validation include quantitative X-ray diffraction based on the Rietveld approach and an application of an external standard (G-factor), calorimetry, analysis of the pore solution composition, thermal analysis, 29Si nuclear magnetic resonance spectroscopy, electron microscopy and surface analysis.The current proposal aims to transfer the model to the hydration of alite in the presence of foreign ions, as a number of ions modify hydration kinetics in different form. It is known that the presence of aluminum from different sources may delay the main hydration period whereas it is accelerated in the presence of dissolved alkalis. The impact of aluminum, sulfate and alkali ions will be analyzed individually and in combination in the present project. This includes also basic research for the analysis of interfacial dissolution and precipitation rates to obtain information on the mechanisms how the foreign ions affect reactivity. These data can be used to extend the current model from pure tricalcium silicate to the hydration of doped alite in the presence of additional ions in the pore solution. The model can be validated using the same experimental methods as in the previous project. Based on findings of the fundamental research, new methods to modify the hydration kinetics will be investigated by modelling and experimental research. The long-term of these efforts goal is understanding and manipulation of cement hydration.

目前每年生产和消费的水泥超过40亿吨。该过程约占人为二氧化碳排放总量的8%，并与一次能源的高消耗有关。水泥用于生产混凝土，混凝土是建筑中最重要的材料。与材料的重要性相比，关于硬化过程中的化学反应的知识只发展得很差。了解水化作用的机理将有助于减少环境影响和开发高性能的粘结剂和混凝土。上一个项目为了解在不存在外来离子的情况下硅酸三钙水化的基本机理做出了非常重要的贡献。首次证明了反应初期的动力学完全取决于C-S-H的析出速率。除了这种定性的演示，定量数据的相关参数，如界面速率，表面积，反应程度和溶液组成进行了分析，并提供给一个简单而强大的动力学模型。该模型可以定量地描述硅酸三钙在无杂质离子存在下的水化过程，计算结果与实验数据吻合较好。用于模型验证的方法包括基于Rietveld方法的定量X射线衍射和外标的应用（G-因子）、量热法、孔溶液组成分析、热分析、29 Si核磁共振光谱、电子显微镜和表面分析。目前的建议旨在将模型转移到存在外来离子的阿利特水化，因为许多离子以不同的形式改变水合动力学。已知来自不同来源的铝的存在可延迟主要水化期，而在溶解碱的存在下，其加速。在本项目中，将单独和组合分析铝、硫酸盐和碱离子的影响。这也包括分析界面溶解和沉淀速率的基础研究，以获得有关外来离子如何影响反应性的机制的信息。这些数据可以用来扩展目前的模型，从纯硅酸三钙掺杂阿利特在孔隙溶液中的额外的离子的存在下的水化。该模型可以使用与先前项目相同的实验方法进行验证。 基于基础研究的结果，将通过模型和实验研究来探索修改水化动力学的新方法。这些努力的长期目标是理解和操纵水泥水化。