Department of Civil and Environmental Engineering, University of California, Berkeley, California 94720, United States.
School of Forestry &Environmental Studies, Yale University, New Haven, Connecticut 06511, United States.
Sci Rep. 2017 Mar 10;7:44032. doi: 10.1038/srep44032.
The incorporation of Al and increased curing temperature promotes the crystallization and cross-linking of calcium (alumino)silicate hydrate (C-(A-)S-H), which is the primary binding phase in most contemporary concrete materials. However, the influence of Al-induced structural changes on the mechanical properties at atomistic scale is not well understood. Herein, synchrotron radiation-based high-pressure X-ray diffraction is used to quantify the influence of dreierketten chain cross-linking on the anisotropic mechanical behavior of C-(A-)S-H. We show that the ab-planar stiffness is independent of dreierketten chain defects, e.g. vacancies in bridging tetrahedra sites and Al for Si substitution. The c-axis of non-cross-linked C-(A-)S-H is more deformable due to the softer interlayer opening but stiffens with decreased spacing and/or increased zeolitic water and Ca of the interlayer. Dreierketten chain cross-links act as 'columns' to resist compression, thus increasing the bulk modulus of C-(A-)S-H. We provide the first experimental evidence on the influence of the Al-induced atomistic configurational change on the mechanical properties of C-(A-)S-H. Our work advances the fundamental knowledge of C-(A-)S-H on the lowest level of its hierarchical structure, and thus can impact the way that innovative C-(A-)S-H-based cementitious materials are developed using a 'bottom-up' approach.
铝的掺入和较高的固化温度促进了钙（铝硅酸盐）水化物（C-(A-)S-H）的结晶和交联，C-(A-)S-H 是大多数现代混凝土材料的主要结合相。然而，铝诱导的结构变化对原子尺度机械性能的影响还不是很清楚。在此，我们使用基于同步辐射的高压 X 射线衍射来定量研究 dreierketten 链交联对 C-(A-)S-H 各向异性力学行为的影响。我们表明，ab 平面的刚度与 dreierketten 链缺陷无关，例如桥接四面体位置的空位和 Si 被 Al 取代。由于较弱的层间开口，未交联的 C-(A-)S-H 的 c 轴更容易变形，但随着层间间距的减小和/或沸石水和 Ca 的增加而变硬。dreierketten 链交联作为“支柱”抵抗压缩，从而提高 C-(A-)S-H 的体积模量。我们提供了第一个关于铝诱导的原子构型变化对 C-(A-)S-H 机械性能影响的实验证据。我们的工作推进了 C-(A-)S-H 在其层次结构最低水平上的基本认识，因此可以影响使用“自下而上”方法开发创新的 C-(A-)S-H 基胶凝材料的方式。
