Growth and porosity of C-S-H phases, development of the `Sheet Growth Model` and coupling with experimental data (1H NMR, SEM)

C-S-H 相的生长和孔隙率、“片层生长模型”的开发以及与实验数据（1H NMR、SEM）的结合

• 批准号: 344069666
• 负责人: Professor Dr.-Ing. Horst-Michael Ludwig
• 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: 2017
• 资助国家: 德国
• 起止时间: 2016-12-31 至 2020-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/344069666?language=en
• 关键词: Growth; porosity; phases; development; Sheet

Understanding the micro-structure and process of formation of Calcium-Silicate-Hydrates (C S H) which are the main products of cement hydration is the key to understand properties and performance of concretes. Improved experimental evidence and parallel development of high resolution modelling allows simulating structural changes and to assess their impacts on macroscopic properties of concrete (shrinkage, strength, durability etc.). During the preceding part of the project the boundaries of fundamental knowledge could be pushed forward significantly. The formation of C S H phases were analysed by high-resolution scanning electron microscopic (SEM) investigations, proton nuclear magnetic resonance spectroscopy (1H-NMR), X ray diffraction analysis (XRD) and mercury intrusion porosimetry (MIP). These experimental results were used to develop the microstructural ‘Sheet Growth’ model further and to tune model parameters. This approach enabled us to simulate the growth of C S H phases that closely resembles microstructural findings (SEM, 1H-NMR) at a scale from 0.5 to 500 nm in three dimensions. In the extended project, the modelling will be based on the strong foundation laid by the previous part of the project. Our model will be extended towards other unhydrated (alite and belite) and hydrated phases (inner C S H, outer C-S-H, CH). Further on we will adjust the morphology and density of the hydrates to real structures and significantly enlarge the modelled domain. This is achieved by combining the ‘Sheet Growth’ model with the ‘Level-Set’ approach. The ‘Level Set’ approach is able to simulate multi-phase transformations over time. We will use the combined models to describe the development of pores, structures and spatial phase distribution in a scale from 0.5 nm to 1000 µm in three dimensions. To make this study complete, the model output will be verified, and parameters will be further calibrated with the following experimental data.Nanotomography investigations using X-Rays and SEM with Focused Ion Beam (FIB) will depict porosity and volume development of the phases three dimensionally and time depended. The combination of these techniques with 1H-NMR spectroscopy and low temperature differential scanning calorimetry on wet and dried samples will allow us to evaluate the development of the pore size distribution at full scale and the water saturation of capillary and larger pores. This data is used directly to make the modelling realistic. In the future, the model obtained in this way can offer the possibility of predicting characteristic values (shrinkage, creep, permeability) of concretes.

水化硅酸钙（C-SH）是水泥水化的主要产物，了解其微观结构和形成过程是理解混凝土性能的关键。改进的实验证据和高分辨率建模的并行开发允许模拟结构变化，并评估其对混凝土宏观性能（收缩，强度，耐久性等）的影响。在项目的前一部分，基础知识的边界可以大大向前推进。用高分辨扫描电镜（SEM）、核磁共振氢谱（1H-NMR）、X射线衍射（XRD）和压汞法（MIP）分析了C-S-H相的形成。这些实验结果被用来进一步发展微观结构的“片状生长”模型，并调整模型参数。这种方法使我们能够模拟生长的C S H相，非常类似于微观结构的发现（SEM，1H-NMR）在一个规模从0.5到500 nm的三维。在扩展项目中，建模将基于项目前一部分奠定的坚实基础。 我们的模型将扩展到其他未水化（阿利特和贝利特）和水化相（内部C-S-H，外部C-S-H，CH）。进一步，我们将调整水合物的形态和密度，使其符合真实的结构，并显著扩大模拟域。这是通过将“片材生长”模型与“水平集”方法相结合来实现的。“Level Set”方法能够模拟随时间的多阶段转换。我们将使用组合模型来描述从0.5 nm到1000 µm的三维尺度上的孔、结构和空间相分布的发展。为了完成这项研究，模型输出将被验证，参数将进一步校准与以下实验data.Nanotomography调查使用X射线和SEM与聚焦离子束（FIB）将描绘孔隙率和体积发展的阶段三维和时间依赖。结合这些技术与1H-NMR光谱和低温差示扫描量热法的湿和干样品将使我们能够评估的发展，在全尺寸的孔径分布和水饱和度的毛细管和较大的孔隙。这些数据直接用于使建模逼真。在未来，以这种方式获得的模型可以提供预测的特征值（收缩，徐变，渗透性）的混凝土。