At 100-nanometer length scale, the mesoscopic structure of calcium silicate hydrate (C-S-H) plays a critical role in determining the macroscopic material properties, such as porosity. In order to explore the mesoscopic structure of C-S-H, we employ two effective techniques, nanoindentation test and molecular dynamics simulation. Grid nanoindentation tests find different porosity of C-S-H in cement paste specimens prepared at varied water-to-cement (w/c) ratios. The w/c-ratio-induced porosity difference can be ascribed to the aspect ratio (diameter-to-thickness ratio) of disk-like C-S-H building blocks. The molecular dynamics simulation, with a mesoscopic C-S-H model, reveals 3 typical packing patterns and relates the packing density to the aspect ratio. Illustrated with disk-like C-S-H building blocks, this study provides a description of C-S-H structures in complement to spherical-particle C-S-H models at the sub-micron scale.
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机译:在100纳米的长度尺度上,水合硅酸钙(C-S-H)的介观结构在确定宏观材料特性(例如孔隙率)方面起着至关重要的作用。为了探索C-S-H的介观结构,我们采用了两种有效的技术:纳米压痕测试和分子动力学模拟。网格纳米压痕测试发现,以不同的水灰比(w / c)制备的水泥浆样品中C-S-H的孔隙率不同。 w / c比引起的孔隙率差异可以归因于盘状C-S-H构件的纵横比(直径与厚度之比)。分子动力学模拟具有介观的C-S-H模型,揭示了3种典型的堆积模式,并将堆积密度与长宽比相关。以圆盘状C-S-H构建块为例进行说明,这项研究对亚微米级球形粒子C-S-H模型的补充提供了C-S-H结构的描述。
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