The kinetics of C3S hydration - Physicochemical modeling with special respect to K+, Al(OH)4- and SO42- in pore solution

C3S 水合动力学 - 孔隙溶液中 K、Al(OH)4- 和 SO42- 的物理化学建模

• 批准号: 522100430
• 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
• 资助国家: 德国
• 项目状态: 未结题
• 来源: https://gepris.dfg.de/gepris/projekt/522100430?language=en
• 关键词: kinetics; C3S; hydration; Physicochemical; modeling

Understanding the chemical processes during cement hydration is essential for the improvement of cements, especially in the context of the challenge of cutting down CO2 emissions from cement production. The main aim is to reduce the proportion of clinker in the cement, which is why the remaining clinker proportion has to become more efficient. Portland cement is by far the most common and widely used cement, whose main constituent is the so-called alite (foreign ion-stabilised Ca3SiO5). Since Portland Cement is multi-phase mixture, alite is used as a simpler model for better understanding underlying chemical processes. Alite is responsible for building up the early and final compressive strengths of the cement during the reaction with water, which is why it is particularly important to understand its reaction with water. Alite reacts with water to form the crystalline phase portlandite (Ca(OH)2) and the nano-structured C-S-H phase. Despite decades of research the precise mechanism of the hydration reaction of alite is not yet finally understood. In recent years, the gain of experimental data has led to the development of a kinetic model for alite hydration, which was verified in the first step without foreign ions in the system. It could be shown that the reaction rates during early hydration can be described very well by the C-S-H precipitation rates. However, since other ions (including aluminium, alkalis, sulphates) are also involved in the hydration of Portland cement, their influence on hydration, especially on the precipitation rates of C-S-H, also had to be clarified. The influence of aluminium and alkalis could be experimentally proven and incorporated into the kinetic model. This proposal now deals with the influence of sulphate on alite hydration, as well as its influence on the other ions (aluminium, alkalis) during the hydration. The precipitation rates of C-S-H have to be investigated and the kinetic model must be extended by a factor for sulphate. Finally, a simulation programme will be set up to reproduce the collected data sets. Through successful model development, data sets from the literature can then be recalculated and the validity of the simulation programme will be checked.

了解水泥水化过程中的化学过程对于改进水泥是至关重要的，特别是在减少水泥生产中二氧化碳排放的挑战的背景下。主要目标是降低水泥中熟料的比例，这就是为什么剩余的熟料比例必须变得更有效率。到目前为止，波特兰水泥是最常见和使用最广泛的水泥，其主要成分是所谓的阿利特(外国离子稳定的Ca3SiO5)。由于波特兰水泥是多相混合物，阿利特被用作更简单的模型，以更好地理解潜在的化学过程。阿利特在与水的反应中负责建立水泥的早期和最终抗压强度，这就是为什么了解它与水的反应特别重要的原因。阿利特与水反应生成晶相Ca(OH)2和纳米结构的C-S-H相。尽管经过几十年的研究，但阿利特水化反应的确切机理尚未最终弄清楚。近年来，随着实验数据的获得，阿利特水化动力学模型得到了发展，并在体系中没有外来离子的情况下得到了第一步的验证。结果表明，C-S-H沉淀速率可以很好地描述早期水化反应速率。然而，由于其他离子(包括铝、碱、硫酸盐)也参与了硅酸盐水泥的水化，它们对水化的影响，特别是对C-S-H的沉淀速率的影响也必须弄清楚。铝和碱的影响可以从实验上得到证实，并被纳入动力学模型。这项建议现在涉及到硫酸盐对阿利特水化的影响，以及它在水化过程中对其他离子(铝、碱)的影响。必须研究C-S-H的沉淀速率，动力学模型必须扩展一个硫酸盐因子。最后，将建立一个模拟程序来再现所收集的数据集。通过成功的模型开发，然后可以重新计算文献中的数据集，并检查模拟程序的有效性。