Department of Materials Science and Engineering, Sir Robert Hadfield Building, Mappin St., University of Sheffield, Sheffield S1 3JD, UK.
Langmuir. 2013 Apr 30;29(17):5294-306. doi: 10.1021/la4000473. Epub 2013 Apr 15.
Structural models for the primary strength and durability-giving reaction product in modern cements, a calcium (alumino)silicate hydrate gel, have previously been based solely on non-cross-linked tobermorite structures. However, recent experimental studies of laboratory-synthesized and alkali-activated slag (AAS) binders have indicated that the calcium-sodium aluminosilicate hydrate [C-(N)-A-S-H] gel formed in these systems can be significantly cross-linked. Here, we propose a model that describes the C-(N)-A-S-H gel as a mixture of cross-linked and non-cross-linked tobermorite-based structures (the cross-linked substituted tobermorite model, CSTM), which can more appropriately describe the spectroscopic and density information available for this material. Analysis of the phase assemblage and Al coordination environments of AAS binders shows that it is not possible to fully account for the chemistry of AAS by use of the assumption that all of the tetrahedral Al is present in a tobermorite-type C-(N)-A-S-H gel, due to the structural constraints of the gel. Application of the CSTM can for the first time reconcile this information, indicating the presence of an additional activation product that contains highly connected four-coordinated silicate and aluminate species. The CSTM therefore provides a more advanced description of the chemistry and structure of calcium-sodium aluminosilicate gel structures than that previously established in the literature.
先前，用于现代水泥中主要强度和耐久性产物的结构模型，即钙（铝）硅酸盐水化物凝胶，仅基于未交联的托贝莫来石结构。然而，最近对实验室合成和碱激活矿渣（AAS）粘合剂的实验研究表明，在这些系统中形成的钙-钠铝硅酸盐水合物[C-(N)-A-S-H]凝胶可以显著交联。在这里，我们提出了一个模型，将 C-(N)-A-S-H 凝胶描述为交联和未交联托贝莫来石基结构的混合物（交联取代托贝莫来石模型，CSTM），这可以更恰当地描述该材料的光谱和密度信息。对 AAS 粘合剂的相组成和 Al 配位环境的分析表明，由于凝胶的结构限制，假设所有四面体 Al 都存在于托贝莫来石型 C-(N)-A-S-H 凝胶中，无法完全解释 AAS 的化学性质。CSTM 的应用首次可以协调这些信息，表明存在含有高度连接的四配位硅酸盐和铝酸盐物种的额外激活产物。因此，CSTM 为钙-钠铝硅酸盐凝胶结构的化学和结构提供了比文献中以前建立的更先进的描述。
