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A realistic molecular model of cement hydrates

机译:水泥水合物的真实分子模型

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摘要

Despite decades of studies of calcium-silicate-hydrate (C-S-H), the structurally complex binder phase of concrete, the interplay between chemical composition and density remains essentially unexplored. Together these characteristics of C-S-H define and modulate the physical and mechanical properties of this "liquid stone" gel phase. With the recent determination of the calcium/silicon (C/S = 1.7) ratio and the density of the C-S-H particle (2.6 g/cm~3) by neutron scattering measurements, there is new urgency to the challenge of explaining these essential properties. Here we propose a molecular model of C-S-H based on a bottom-up atomistic simulation approach that considers only the chemical specificity of the system as the overriding constraint. By allowing for short silica chains distributed as monomers, dimers, and pentamers, this C-S-H archetype of a molecular description of interacting CaO, SiO_2, and H_2O units provides not only realistic values of the C/S ratio and the density computed by grand canonical Monte Carlo simulation of water adsorption at 300 K. The model, with a chemical composition of (CaO)_(1.65)(SiO_2)(H_2O)_(1.75), also predicts other essential structural features and fundamental physical properties amenable to experimental validation, which suggest that the C-S-H gel structure includes both glass-like short-range order and crystalline features of the mineral tobermorite. Additionally, we probe the mechanical stiffness, strength, and hydrolytic shear response of our molecular model, as compared to experimentally measured properties of C-S-H. The latter results illustrate the prospect of treating cement on equal footing with metals and ceramics in the current application of mechanism-based models and multiscale simulations to study inelastic deformation and cracking.
机译:尽管数十年来对结构复杂的混凝土粘结相硅酸钙水合物(C-S-H)进行了研究,但化学成分和密度之间的相互作用基本上尚未得到探索。 C-S-H的这些特征共同定义并调节了这种“液态石”凝胶相的物理和机械性能。随着最近通过中子散射测量确定钙/硅比(C / S = 1.7)和C-S-H颗粒的密度(2.6 g / cm〜3),对解释这些基本性质的挑战提出了新的紧迫性。在这里,我们提出了一种基于自下而上的原子模拟方法的C-S-H分子模型,该方法仅将系统的化学特异性视为主要约束条件。通过允许短的二氧化硅链作为单体,二聚体和五聚体分布,这种相互作用的CaO,SiO_2和H_2O单元的分子描述的CSH原型不仅提供了实际的C / S比值,而且还提供了由经典正则Monte计算的密度在300 K下水吸附的Carlo模拟。该模型的化学成分为(CaO)_(1.65)(SiO_2)(H_2O)_(1.75),还预测了其他重要的结构特征和基本物理性质,适合进行实验验证,这表明CSH凝胶结构既包含玻璃状短程有序,又包含矿质蒙脱石的晶体特征。此外,与实验测量的C-S-H特性相比,我们探索了分子模型的机械刚度,强度和水解剪切响应。后一结果说明了在当前基于机理的模型和多尺度模拟研究非弹性变形和开裂的当前应用中,用金属和陶瓷在水泥基础上处理水泥的前景。

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  • 作者单位

    Centre Interdisciplinaire des Nanosciences de Marseille, Centre National de la Recherche Scientifique and Marseille Universite, Campus de Luminy, Marseille, 13288 Cedex 09, France Departments of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139;

    Departments of Nuclear Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139;

    Departments of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139;

    Departments of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139;

    Departments of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139;

    Departments of Nuclear Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139 Departments of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139;

    Departments of Civil and Environmental Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139;

  • 收录信息 美国《科学引文索引》(SCI);美国《生物学医学文摘》(MEDLINE);美国《化学文摘》(CA);
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

    atomistic simulation; mechanical properties; structural properties;

    机译:原子模拟机械性能结构性质;

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