Hydration of Concrete: The First Steps.
Hydration of Concrete: The First Steps.
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DOI：
10.1002/chem.201705974
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发表时间：
2018-06
期刊：
影响因子：
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通讯作者：
P. Thissen;C. Natzeck;Nicolás Giraudo;P. Weidler;C. Wöll
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文献类型：
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作者：
P. Thissen;C. Natzeck;Nicolás Giraudo;P. Weidler;C. Wöll
混凝土是人类使用的最重要的建筑材料，同时也是材料科学中已知的最复杂的物质之一。由于这种矿物化合物是高度多孔的，因此迫切需要更好地了解其表面化学，特别是与水的反应，以了解和避免建筑物和桥梁等基础设施的腐蚀。通过将所谓的表面科学方法应用于定义明确的矿物硅灰石，我们已经深入了解了混凝土与水接触时的质子转移。从IR（红外）光谱的数据表明，这种硅酸钙（CS）基板暴露于H2 O导致解离和OH-物种的形成。这种质子转移是一种非常重要的化学反应，因为一方面它触发了水泥转化为混凝土（硅酸钙水合物相），但另一方面也控制了混凝土的腐蚀。有趣的是，我们发现当相同的表面暴露于甲醇时，没有质子转移发生。为了理解这种意想不到的差异，获得的光谱数据的分析是由一个详细的，第一原理计算研究采用密度泛函理论（DFT）的帮助。结合实验和理论的努力，可以推导出一个一致的图片发生在CS和CSH阶段的质子转移反应。将讨论在恶劣的水环境中保护城市基础设施免受腐蚀的策略的影响。
Concrete is the most important construction material used by mankind and, at the same time, one of the most complex substances known in materials science. Since this mineral compound is highly porous, a better understanding of its surface chemistry, and in particular the reaction with water, is urgently required to understand and avoid corrosion of infrastructure like buildings and bridges. We have gained insight into proton transfer from concrete upon contact with water by applying the so-called Surface Science approach to a well-defined mineral, Wollastonite. Data from IR (infrared) spectroscopy reveal that exposure of this calcium-silicate (CS) substrate to H2 O leads to dissociation and the formation of OH-species. This proton transfer is a chemical reaction of key importance, since on the one hand it triggers the conversion of cement into concrete (a calcium-silicate-hydrate phase), but on the other hand also governs the corrosion of concrete. Interestingly, we find that no proton transfer takes place when the same surface is exposed to methanol. In order to understand this unexpected difference, the analysis of the spectroscopic data obtained was aided by a detailed, first-principles computational study employing density functional theory (DFT). The combined experimental and theoretical effort allows derivation of a consistent picture of proton transfer reactions occurring in CS and CSH phases. Implications for strategies to protect this backbone of urban infrastructure from corrosion in harsh, aqueous environments will be discussed.