Sowoidnich T, Damidot D, Ludwig H-M, Germroth J, Rosenberg R, Cölfen H
Bauhaus-Universität Weimar, F.A. Finger-Institute for Building Materials Science, Coudraystr. 11, 99423 Weimar, Germany.
IMT Nord Europe, Institut Mines-Télécom, University Lille, Centre for Materials and Processes Centre, F-59000 Lille, France.
J Chem Phys. 2023 Mar 21;158(11):114309. doi: 10.1063/5.0141255.
The nucleation and growth of calcium-silicate-hydrate (C-S-H) is of fundamental importance for the strength development and durability of the concrete. However, the nucleation process of C-S-H is still not fully understood. The present work investigates how C-S-H nucleates by analyzing the aqueous phase of hydrating tricalcium silicate (CS) by applying inductively coupled plasma-optical emission spectroscopy as well as analytical ultracentrifugation. The results show that the C-S-H formation follows non-classical nucleation pathways associated with the formation of prenucleation clusters (PNCs) of two types. Those PNCs are detected with high accuracy and reproducibility and are two species of the 10 in total, from which the ions (with associated water molecules) are the majority of the species. The evaluation of the density and molar mass of the species shows that the PNCs are much larger than ions, but the nucleation of C-S-H starts with the formation of liquid precursor C-S-H (droplets) with low density and high water content. The growth of these C-S-H droplets is associated with a release of water molecules and a reduction in size. The study gives experimental data on the size, density, molecular mass, and shape and outlines possible aggregation processes of the detected species.
硅酸钙水合物（C-S-H）的成核与生长对于混凝土的强度发展和耐久性至关重要。然而，C-S-H的成核过程仍未被完全理解。本研究通过应用电感耦合等离子体发射光谱法以及分析超速离心法分析水化硅酸三钙（CS）的水相，来研究C-S-H是如何成核的。结果表明，C-S-H的形成遵循与两种类型的预成核簇（PNCs）形成相关的非经典成核途径。这些PNCs能够以高精度和可重复性被检测到，并且总共10种类型中有两种，其中离子（带有相关水分子）是大多数类型。对这些类型的密度和摩尔质量的评估表明，PNCs比离子大得多，但C-S-H的成核始于低密度和高含水量的液态前驱体C-S-H（液滴）的形成。这些C-S-H液滴的生长与水分子的释放和尺寸的减小有关。该研究给出了关于所检测类型的尺寸、密度、分子量和形状的实验数据，并概述了可能的聚集过程。
