Capabilities for property assessment on different levels of the micro-structure of DEM-simulated cementitious materials
Capabilities for property assessment on different levels of the micro-structure of DEM-simulated cementitious materials
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DOI：
10.1016/j.conbuildmat.2015.04.012
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发表时间：
2015-07
影响因子：
7.4
通讯作者：
P. Stroeven;K. Li;N. Le;Huan He;M. Stroeven
中科院分区：
文献类型：
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作者：
P. Stroeven;K. Li;N. Le;Huan He;M. Stroeven
随着计算机技术的飞速发展，对混凝土等颗粒材料进行三维DEM模拟已成为可能。这将是一个有吸引力的替代系统物理实验，更耗时，劳动密集，因此昂贵。本文讨论了骨料结构的中观水平和被骨料颗粒包围的新鲜粘结材料的微观水平的模拟。在后一种情况下，将进行水化模拟，以获得成熟的材料。这可以扩展到C-S-H的纳米级颗粒包装，完成三尺度方法。对于机械性能的评估，填料密度是一个可以直接研究的关键问题。与工程相关的一个主要课题是由于耐久性问题而产生的孔隙度。这需要描绘毛细管孔隙网络结构的技术，以便能够评估其拓扑和几何性质。通过将这些特征与所谓的管网模型中的水力特性相结合，基本上可以估计混凝土的输送特性，这是潜在的长期强度问题。工艺参数对填料特性的影响对于优化胶凝复合材料的填料、强度和耐久性具有重要意义。本文将提供一个完整的方法主线，包括现代三尺度模拟DEM方法、水化模拟、孔隙描绘和测量。意图不是讨论方法的单独“构建块”，因为它们已经在前面的出版物中被提出、讨论和验证了。此外，还将指出该方法的典型功能。为此，将提出结果，以说明骨料包装中涉及的形状问题，细粒稻壳灰混合水泥对孔隙特征和由此产生的渗透性的积极影响，以及在含有毛细水的孔隙实际情况下的渗透性估计。
Realistic three-scale simulation by DEM of particulate materials like concrete is nowadays possible by fast developments in computer technology. This would be an attractive alternative for systematic physical experimenting that is more time-consuming, labour-intensive and thus expensive. The paper discusses the simulation on meso-level of the aggregate structure and on micro-level of the fresh binder material that is enclosed by aggregate grains. In the latter case, it will be followed by hydration simulation to obtain the matured material. This can be expanded to involve particle packing of the C–S–H on nano-level, completing the three-scale approach. For assessment of mechanical properties, packing density is a crucial issue that can be straightforwardly studied. A subject of major engineering relevance is porosity because of durability issues. This requires techniques for delineating the capillary pore network structure to be able assessing its topological and geometric properties. By combining such features with hydraulic properties in a so called tube network model, basically transport properties of concrete can be estimated that are underlying long-term strength issues. Influences of technological parameters on packing characteristics are of interest for optimising packing, strength and durability of cementitious composites. The paper will offer the main lines of a complete methodology involving a modern three-scale analogue DEM approach, hydration simulation, and pore delineation and measuring. Intension is not to discuss separate “building blocks” of the methodology, because they have been presented, discussed and validated earlier in publications. Additionally, typical capabilities of the methodology will be indicated. To do so, results will be presented for illustrative purposes on the shape issue involved in aggregate packing, on the positive effects of cement blending by fine-grained rice husk ash on pore characteristics and resulting permeability, and on permeability estimation in the practical case of pores containing capillary water.