Hydrogel-based concretes (HBCs) are an emerging class of load-bearing composite materials consisting of inert particles joined together by micro-hydrogel joints. As HBCs can harden via sol-gel process and H2O phase changes under a freezing temperature and vacuum, they are suitable for future exterritorial constructions. Previous studies have demonstrated that the internal microstructure of the hydrogel joints in HBC varies significantly with curing temperature and air pressure, leading to variations in their mechanical properties. In this study, we present a new multi-scale model that quantitatively predicts the mechanical properties of HBC formed under different curing environments including Martian atmosphere. On the micro-scale, four representative joint microstructures are studied, including tubular, foamy, honeycomb, and tube-cased-foam joints. We experimentally studied and analytically derived the constitutive relationship between the joint force and displacement. Particularly, we determined the process of hydrogel skin peeling from the particle's surface of tubular joints based on force and energy equilibrium. On the macro-scale, we simplified the constitutive joint relationships in a linear parallel bond model (LPM) and employed them to quantify interparticle relationships in a discrete element method (DEM)-based HBC model. The Weibull distribution is used to consider the variation of tensile and shear strengths of the hydrogel joints in the DEM. The modeling results are not only validated with the experimentally acquired compressive stress-strain curves of HBC, but also accurately predict the combined influence of mix design and curing conditions on the mechanical properties.

中文翻译：

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在火星周围环境和极端恶劣环境下形成的水凝胶基混凝土的多尺度建模


水凝胶基混凝土 （HBC） 是一类新兴的承重复合材料，由微水凝胶接头连接在一起的惰性颗粒组成。由于 HBC 可以在冷冻温度和真空下通过溶胶-凝胶过程和 H2O 相变硬化，因此适用于未来的外部结构。以前的研究表明，HBC 中水凝胶接头的内部微观结构随固化温度和气压的变化而显着变化，导致其机械性能发生变化。在这项研究中，我们提出了一种新的多尺度模型，该模型定量预测了在包括火星大气在内的不同固化环境下形成的 HBC 的机械性能。在微观尺度上，研究了四种具有代表性的接头微观结构，包括管状、泡沫状、蜂窝状和管状泡沫接头。我们实验研究和分析推导出了关节力和位移之间的本构关系。特别是，我们根据力和能量平衡确定了水凝胶皮肤从颗粒管状关节表面剥离的过程。在宏观尺度上，我们简化了线性平行键模型 （LPM） 中的本构关节关系，并将它们用于量化基于离散元法 （DEM） 的 HBC 模型中的粒子间关系。Weibull 分布用于考虑 DEM 中水凝胶接头的拉伸强度和剪切强度的变化。建模结果不仅通过实验获得的 HBC 压缩应力-应变曲线进行了验证，而且准确预测了混合设计和固化条件对机械性能的综合影响。