Improving the quantitative analysis of cementitious materials by solid state NMR

传统上，胶凝材料通过X射线衍射（XRD）分析，以获得样品中所含各个相的定性和定量信息。这种方法的使用在大多数实验室中是常规的，并基于长期的经验。它对晶体材料非常有用，而对非晶体材料的分析则很复杂。固态核磁共振（NMR）光谱已被证明是一个合适的工具来分析含有无定形和结晶材料的胶凝材料。水泥工业对矿渣、煅烧粘土和粉煤灰等非结晶材料的使用越来越多，这就需要这种分析能力。NMR光谱中的定性鉴定基于单个物质的化学位移数据，定量信息与这些共振的相对强度相关。虽然获取和评估NMR光谱的基本思想是众所周知的，但必须解决一些细节，这些细节使可靠的定量数据的提取严重复杂化。分析通常基于个人经验，并因实验室而异。为了解决这一问题，一些学术机构打算重点研究这一问题。这是指完整的分析程序，包括生产合适的样品，采用最佳采集参数，推荐反卷积程序和数据后处理，以提取样品中各个相的浓度。我们还打算向我们网络之外的其他合作伙伴提供测试样本和改进的例程，以供进一步实践和教育。这种合作还将有助于查明系统误差和随机误差，并提供有关结果标准偏差的信息。预计这项工作将促进应用核磁共振定量分析胶凝材料在无水和水合状态。NMR光谱是一种相当复杂的分析方法，这种努力需要许多努力，而不仅仅是简单的数据采集，这包括：改进的策略，以考虑不同的弛豫时间，选择性溶解方法，以提取个人的共振形状和其他细节。本工作主要集中在29Si NMR方面。其他将被研究的NMR同位素是27 Al和1H。这项工作是与丹麦奥胡斯大学的Jorgen Skibsted教授密切合作进行的，他是水泥材料NMR光谱学领域的领先专家。

Traditionally, cementitious materials are analyzed X-ray diffraction (XRD) to obtain qualitative and quantitative information about the individual phases contained in the sample. The use of this method is routine in most labs and based on long-term experience. It is highly useful for crystalline materials whereas analysis of amorphous materials is complicated. Solid-state Nuclear Magnetic Resonance (NMR) spectroscopy has been proven to be a suitable tool to analyze cementitious materials containing amorphous and crystalline materials. Such analytical capabilities are demanded by the increasing use of non-crystalline materials by the cement industry such as slags, calcined clays and fly ashes. The qualitative identification in the NMR spectra is based on the chemical shift data for the individual substances and the quantitative information is associated to the relative intensity of those resonances. While the basic ideas for the acquisition and evaluation of NMR spectra are very well known, a number of details must be addressed that seriously complicates the extraction of reliable quantitative data. The analysis is often based on individual experience and varies between the laboratories. To address this situation, a group of academic institutions intends to focus on this problem. This refers to the complete analytical procedure including the production of suitable samples, adoption of best acquisition parameters, recommendation for the deconvolution procedures and the post treatment of the data to extract the concentration of the individual phases in the sample. We intend to provide test samples and improved routines also to other partners beyond our network for further practice and education. The cooperation will also allow identification of systematic and random errors and provide information about the standard deviation of the results. It is expected that this work will foster the application of NMR for quantitative analysis of cementitious materials in the anhydrous and hydrated state. NMR spectroscopy is a rather complicated analytical method and such efforts demand a number of efforts beyond a simple data acquisition and this includes: improved strategies to account for the different relaxation times, selective dissolution methods to extract the individual resonance shapes and other details. This work will mainly focus on 29Si NMR. Other NMR isotopes that will be studied are 27Al and 1H.The efforts are conducted in close cooperation with Prof. Jorgen Skibsted from Aarhus University in Denmark, the leading expert in the field of NMR spectroscopy of cementitious materials.