Characterizing Paste Microstructure during Setting with Combined Raman Spectroscopy and Confocal Microscopy

结合拉曼光谱和共焦显微镜表征凝固过程中的膏体微观结构

• 批准号: 1265983
• 负责人: Zhihui Sun
• 金额: $ 20万
• 依托单位: University of Louisville Research Foundation Inc
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2013
• 资助国家: 美国
• 起止时间: 2013-08-15 至 2017-07-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=1265983&HistoricalAwards=false
• 关键词: Characterizing; Paste; Microstructure; during; Setting

The research goal of this project is to enhance our knowledge of cement setting on microstructural level by exploring the dispersion, agglomeration and percolation mechanism of cement particles with advanced physical and chemical imaging methods. To achieve this goal, Raman spectroscopy combined with confocal microscopy will be conducted in real-time on fresh cement pastes. Raman spectroscopy will firstly be applied to both dry cement powder and fresh paste to trace changes in the chemical compositions during early hydration. A Raman library of clinker phases and hydration products will be developed. Then, the Raman spectroscopy will be combined with confocal microscopy to conduct real-time observation on the physical dispersion of particles together with chemical dispersion (chemical mapping) in order to investigate the influence of chemical ingredients and surface chemistry of the particle flocculation. The physical and chemical microstructural parameters will be correlated to the setting time and hydration heat signature using a moving window modeling approach. The setting and hardening process is considered to be the most critical time period for a concrete structure, during which chemical, physical and mechanical properties of the concrete undergo rapid changes. Remixing, recasting, or replacing cannot be implemented after setting. Thus having solid knowledge about the setting behavior of concrete is essential to guarantee the quality and performance of the material. Concrete setting is governed by paste setting that is caused by the distribution, movement, and connection of cement particles. An in-situ observation of the particle flocculation, agglomeration and percolation processes during the initial hydration period will provide fundamental understanding of paste setting behavior, so that the concrete construction process can be controlled. By combining Raman spectroscopy and confocal microscopy, this proposed work will build up a database on early-age hydration that will be useful to the concrete industry, specifically chemical admixture companies. This database will also be useful for hydration/microstructural development models. Educational plan focuses on training undergraduate and graduate students with better critical thinking and research skills. Outreach activities, such as INSPIRE and E-Expo, are also planned for diverse groups of K-12 students, including minority and female students.

本课题的研究目标是利用先进的物理化学成像手段，探索水泥颗粒的分散、团聚和渗流机理，从微观结构水平上加深对水泥凝结的认识。为了实现这一目标，拉曼光谱和共聚焦显微镜将在新水泥浆体上实时进行。拉曼光谱将首先应用于干燥的水泥粉末和新鲜的浆体，以跟踪早期水化过程中化学成分的变化。将建立熟料相和水化产物的拉曼库。然后，将拉曼光谱与共聚焦显微镜相结合，对颗粒的物理分散和化学分散(化学图谱)进行实时观察，以考察化学成分和表面化学对颗粒絮凝的影响。利用移动窗口建模方法，将物理和化学微观结构参数与凝结时间和水化热特征关联起来。凝结硬化过程被认为是混凝土结构最关键的一段时间，在此期间混凝土的化学、物理和力学性能都会发生快速变化。设置后不能进行重混、重铸或替换。因此，对混凝土的凝结性能有扎实的了解，对于保证材料的质量和性能是必不可少的。混凝土的凝结是由水泥颗粒的分布、移动和连接引起的凝结。对混凝土水化初期颗粒的凝聚、凝聚和渗流过程进行现场观测，可以从根本上了解浆体的凝结行为，从而对混凝土施工过程进行控制。通过结合拉曼光谱和共聚焦显微镜，这项拟议的工作将建立一个关于早期水化的数据库，这将对混凝土行业，特别是化学外加剂公司有用。该数据库还将对水化/微结构发展模型有用。教育计划的重点是培养具有更好的批判性思维和研究技能的本科生和研究生。还计划为不同的K-12学生群体，包括少数族裔学生和女性学生，开展INSPIRE和E-EXPO等外联活动。