Improved Low-field NMR porosity characterization of cementitious materials containing water-soluble organic admixtures

IF 10.8 1区工程技术 Q1 CONSTRUCTION & BUILDING TECHNOLOGY

Cement & concrete composites Pub Date : 2024-08-26 DOI:10.1016/j.cemconcomp.2024.105732

Lixiao Zhao , Pan Feng , Jinxiang Hong , Qi Liu , Guoqing Geng

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Abstract

Water-soluble organic admixtures (WSOAs) are widely used in cementitious materials, and may affect the porosity, but their effects on low-field nuclear magnetic resonance (LF-NMR) measurement are often overlooked. Using viscosity modifying admixture (VMA) as an example, this study demonstrates the presence of WSOAs would lead to an overestimation of porosity and a leftward shift of pore size distribution using LF-NMR. This is attributed to the formation of hydrogen bonds between polymer and water molecules, and the decreased distance between nuclear spins, respectively. A strategy is proposed to improve the accuracy of the porosity characterization by eliminating the additional effects of WSOAs in LF-NMR testing. The results show that the addition of small molecular mass non-ionic VMAs replacing mixing water (within a 20 % replacing rate) does not alter the porosity of the paste. This method can be extended to characterize the porosity of various porous materials containing WSOAs.

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改进含有水溶性有机外加剂的水泥基材料的低场核磁共振孔隙率表征

水溶性有机外加剂（WSOAs）被广泛应用于水泥基材料中，可能会影响孔隙率，但它们对低场核磁共振（LF-NMR）测量的影响往往被忽视。本研究以粘度改性外加剂（VMA）为例，证明了 WSOAs 的存在会导致高估孔隙率，并使低场核磁共振的孔径分布左移。这分别归因于聚合物和水分子之间形成的氢键以及核自旋之间距离的减小。我们提出了一种策略，通过消除低频-核磁共振测试中 WSOAs 的额外影响来提高孔隙率表征的准确性。结果表明，添加小分子质量的非离子 VMA 替代混合水（替代率在 20% 以内）不会改变浆料的孔隙率。该方法可扩展用于表征含有 WSOAs 的各种多孔材料的孔隙率。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Cement & concrete composites 工程技术-材料科学：复合

CiteScore

18.70

自引率

11.40%

发文量

459

审稿时长

65 days

期刊介绍： Cement & concrete composites focuses on advancements in cement-concrete composite technology and the production, use, and performance of cement-based construction materials. It covers a wide range of materials, including fiber-reinforced composites, polymer composites, ferrocement, and those incorporating special aggregates or waste materials. Major themes include microstructure, material properties, testing, durability, mechanics, modeling, design, fabrication, and practical applications. The journal welcomes papers on structural behavior, field studies, repair and maintenance, serviceability, and sustainability. It aims to enhance understanding, provide a platform for unconventional materials, promote low-cost energy-saving materials, and bridge the gap between materials science, engineering, and construction. Special issues on emerging topics are also published to encourage collaboration between materials scientists, engineers, designers, and fabricators.