Reaction Mechanisms for the Formation of C-S-H Gel During the Early Hydration of Cement

水泥早期水化过程中C-S-H凝胶形成的反应机理[摘要]当水泥和水混合时，形成的膏体通常在凝固和硬化之前保持流体状态数小时。这段时间，即诱导期，在技术上是极其重要的，因为它允许有足够的时间进行混凝土的混合、运输和浇筑到位。诱导期突然结束，随后是一段加速反应，导致凝固和硬化。波特兰水泥混凝土的通用性和广泛使用，在很大程度上是由于能够通过使用化学外加剂来控制这些水化过程，例如延长和易期或缩短凝结时间。尽管混凝土硬化过程对建筑工业至关重要，而且这些化学外加剂在工业上具有重要意义，但水泥水化过程的基本化学机制还没有得到很好的理解。这个问题在文献中已经争论了100多年，但没有解决。近年来，现代分析技术为水泥水化形成的反应产物提供了新的信息。这些新发现导致了定量纳米级水泥浆体模型的发展，其中一个提议，这是越来越多的接受。此外，最近在NSF的支持下，获得了有关水泥中主要反应产物的结构和溶解度的新信息。这些知识为控制水泥浆和混凝土硬化速率的机制提供了新的见解，并有望更深入地了解水泥和水之间的反应。它不仅为控制水泥浆体水化速率，而且为控制微观结构从而控制最终混凝土的性能打开了大门。这将对为混凝土提供化学外加剂的行业产生重大影响，并对向混凝土中添加各种材料的整体效果产生重大影响。

Reaction Mechanisms for the Formation of C-S-H Gel During the Early Hydration of CementAbstractWhen cement and water are mixed the resulting paste typically stays fluid for several hours before it sets and hardens. This period of time, the induction period, is technically extremely important because it allows enough time for the concrete to be mixed, transported, and poured into place. The induction period ends abruptly and is followed by a period of accelerating reaction that leads to setting and hardening. The versatility and widespread use of Portland cement concrete results, to a large extent, from the ability to control these hydration processes by the use of chemical admixtures, for example to either to extend the period of workability or shorten the time to set. Despite the fundamental importance of the concrete hardening process to the construction industry, and the fact that these chemical admixtures are of significant industrial importance, the fundamental chemical mechanisms underlying the cement hydration process are not well understood. This problem has been debated in the literature for more than 100 years without resolution. In recent years, modern analytical techniques have provided new information about the reaction products formed by the hydration of cement. These new findings led to the development of a quantitative nanometer-level model of cement paste by one of the present proposers, which is receiving increasing acceptance. Also, recently under NSF support new information about the structure and solubility of the main reaction product in cement has been obtained. This knowledge has provided new insight about the mechanisms that control the rate that cement paste and concrete hardens, and the promise of a much deeper understanding of the reactions between cement and water. It also opens the door not only to controlling the rate of hydration of cement paste, but also to controlling the microstructure and thus the properties of the final concrete. This will have a significant impact on the industry that supplies chemical admixtures for concrete, and on understanding the overall effects of adding a wide variety of materials to concrete.