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

了解水泥水化过程中的化学过程对于水泥的改进至关重要，特别是在水泥生产中减少二氧化碳排放的挑战背景下。主要目的是减少熟料在水泥中的比例，这就是为什么剩余的熟料比例必须变得更有效。波特兰水泥是迄今为止最常见和广泛使用的水泥，其主要成分是所谓的alite（外来离子稳定的Ca3SiO5）。由于波特兰水泥是多相混合物，alite被用作更简单的模型，以便更好地理解潜在的化学过程。在水泥与水的反应过程中，Alite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。Alite与水反应形成结晶相portlandite （Ca(OH)2）和纳米结构的C-S-H相。尽管经过了几十年的研究，人们仍未完全了解阿利特水化反应的确切机理。近年来，随着实验数据的增加，建立了一种alite水化动力学模型，并在体系中没有外来离子的情况下进行了第一步验证。结果表明，C-S-H沉淀率可以很好地描述水化初期的反应速率。然而，由于其他离子（包括铝、碱、硫酸盐）也参与波特兰水泥的水化，因此它们对水化的影响，特别是对C-S-H的沉淀速率的影响，也必须加以澄清。铝和碱的影响可以通过实验证明并纳入动力学模型。这个建议现在处理硫酸盐对铝石水化的影响，以及在水化过程中它对其他离子（铝、碱）的影响。必须对C-S-H的沉淀速率进行研究，并将动力学模型扩展为硫酸盐的一个因子。最后，将建立一个模拟方案，以重现所收集的数据集。通过成功的模型开发，可以重新计算文献中的数据集，并检查模拟程序的有效性。

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.