Tobermorite/jennite- and tobermorite/calcium hydroxide-based models for the structure of C-S-H:: applicability to hardened pastes of tricalcium silicate, β-dicalcium silicate, Portland cement, and blends of Portland cement with blast-fumace slag, metakaolin, or silica fume
Tobermorite/jennite- and tobermorite/calcium hydroxide-based models for the structure of C-S-H:: applicability to hardened pastes of tricalcium silicate, β-dicalcium silicate, Portland cement, and blends of Portland cement with blast-fumace slag, metakaolin, or silica fume
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DOI：
10.1016/j.cemconres.2004.05.034
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发表时间：
2004-09-01
影响因子：
11.4
通讯作者：
Richardson, IG
中科院分区：
文献类型：
--
作者：
Richardson, IG
本文的目的是讨论托伯莫里石-jermite （T/J）和托伯莫里石-固溶型氢氧化钙（T/CH）观点对实际水泥浆中C-S-H纳米结构的适用性。考虑到作者1992年的模型有助于讨论，该模型包括两种结构观点的公式；概述了它与其他近期模型的关系。模型的结构细节用一些示意图清楚地说明了。考虑了不同胶凝体系中存在的C-S-H性质的实验观察。在一些系统中，数据只能在T/CH结构观点上进行解释，而在其他系统中，T/CH和T/J观点都可以适用。介绍了透射电子显微镜（TEM）的新数据。相对较大的C(3)S或alite颗粒中的“内产物”（Ip） C-S- h似乎由小的球状颗粒组成，在20℃水合的糊状中，其大小约为4-8微米，但在高温下较小，约为3-4纳米。C3S或β - c (2)S糊体中的“外产物”（Op） C-S-H的原纤维似乎由长而薄的颗粒聚集而成，这些颗粒的最小尺寸约为3nm，长度从几纳米到几十纳米不等。这些C-S-H粒子的小尺寸可能会导致显著的边缘效应，这似乎为Q(0)(H)物种的持久性提供了合理的解释。这也可以解释为什么在高温下会有更多的Q(0)(H)，因为颗粒看起来更小，而在koh活化的糊中，C-S-H具有箔状形态，显然更少。在混合水泥中，C-S-H平均Ca/Si比的降低导致从纤维状到皱褶箔状形态的变化，这强烈表明，随着Ca/Si比的降低，C-S-H颗粒的生长发生了从一维到二维的转变；即，长而薄的颗粒到箔片。箔状形态与基结构有关。C-S-H存在于高Ca/Si比的小的全水合alite颗粒中，其产物密度较低，孔隙率较大；其形貌与水活性纯渣膏中形成的细箔状Op C-S-H非常相似，具有较低的Ca/Si比。因此，小晶石颗粒中的C-S-H基本上是基于基的（并且主要是二聚体），这是合理的。由于完全基于C-S-H可能与主要由j基结构组成的C-S-H具有不同的性质，因此在小的完全反应颗粒中的C-S-H可能与在膏体中其他地方形成的C-S-H具有不同的性质；这可能会产生重要的影响。(C) 2004 Elsevier Ltd.版权所有。
The purpose of this article is to discuss the applicability of the tobermorite-jermite (T/J) and tobermorite-'solid-solution' calcium hydroxide (T/CH) viewpoints for the nanostructure of C-S-H present in real cement pastes. The discussion is facilitated by a consideration of the author's 1992 model, which includes formulations for both structural viewpoints; its relationship to other recent models is outlined. The structural details of the model are clearly illustrated with a number of schematic diagrams. Experimental observations on the nature of C-S-H present in a diverse range of cementitious systems are considered. In some systems, the data can only be accounted for on the T/CH structural viewpoint, whilst in others, both the T/CH and T/J viewpoints could apply. New data from transmission electron microscopy (TEM) are presented. The 'inner product' (Ip) C-S-H in relatively large grains Of C(3)S or alite appears to consist of small globular particles, which are approximate to 4-8 run in size in pastes hydrated at 20 degreesC but smaller at elevated temperatures, approximate to 3-4 nm. Fibrils of 'outer product' (Op) C-S-H in C3S or beta-C(2)S pastes appear to consist of aggregations of long thin particles that are about 3 nm in their smallest dimension and of variable length, ranging from a few nanometers to many tens of nanometers. The small size of these particles of C-S-H is likely to result in significant edge effects, which would seem to offer a reasonable explanation for the persistence of Q(0)(H) species. This would also explain why there is more Q(0)(H) at elevated temperatures, where the particles seem to be smaller, and apparently less in KOH-activated pastes, where the C-S-H has foil-like morphology. In blended cements, a reduction in the mean Ca/Si ratio of the C-S-H results in a change from fibrillar to a crumpled-foil morphology, which suggests strongly that as the Ca/Si ratio is reduced, a transition occurs from essentially one-dimensional growth of the C-S-H particles to two-dimensional; i.e., long thin particles to foils. Foil-like morphology is associated with T-based structure. The C-S-H present in small fully hydrated alite grains, which has high Ca/Si ratio, contains a less dense product with substantial porosity; its morphology is quite similar to the fine foil-like Op C-S-H that forms in water-activated neat slag pastes, which has a low Ca/Si ratio. It is thus plausible that the C-S-H in small alite grains is essentially T-based (and largely dimeric). Since entirely T-based C-S-H is likely to have different properties to C-S-H consisting largely of J-based structure, it is possible that the C-S-H in small fully reacted grains will have different properties to the C-S-H formed elsewhere in a paste; this could have important implications. (C) 2004 Elsevier Ltd. All rights reserved.