Optimizing the Temperature and Chemical Stability of Fly Ash Aluminosilicate Composites at the Nanoscale

该研究项目的重点是了解和优化用于高温应用的低能量水泥基复合材料的耐温度和抗碳化性能，如防火墙和耐火材料。由于材料制造和运输的需要，波特兰水泥和耐火混凝土在社会中的使用占相当大的能量利用量。此外，波特兰水泥基混凝土在高温下由于主要强度赋予成分的分解而不能充分地发挥作用，导致昂贵的维修和更换。在该项目中进行的研究将促进在建筑和耐火材料行业中使用工业副产品，从而鼓励进一步减少与这些部门相关的能源使用。该项目的研究成果将纳入高中能源和环境相关材料的教学单元。关于促进和鼓励在科学、技术、工程和数学领域代表性不足的少数群体，包括年轻女性，该项目将使高中和大学生实习生在暑期和学年期间接受研究培训。该研究项目的目标是发现和优化化学活化水泥复合材料的高温稳定性和抗碳化性，基于铝硅酸盐化学，使用多方面的实验方法。环境温度反应动力学和凝固时间将使用超声波分析结合等温量热法进行研究，其中钙基添加剂将用于控制凝固时间和短期机械行为。化学活化偏高岭土和粉煤灰基膏体的分子结构将使用X射线对分布函数分析和红外光谱法在一系列高温下进行阐明，该项目将包括在同步加速器设施中使用原位碳酸化/高温测量。此外，考虑到胶凝材料对脱水引起的开裂和机械性能损失的敏感性，氧化铝颗粒和纤维增强对铝硅酸盐复合材料的微观结构（和原子）行为的影响将使用同步加速器和基于实验室的X射线显微断层摄影术来揭示。最终，该项目将产生在高温下低能量铝硅酸盐水泥的原子和微观结构行为的基础知识，长期目标是将这种材料整合到传统混凝土由于暴露于高温和侵蚀性化学品而迅速降解的应用中。

This research project centers on understanding and optimizing the temperature and carbonation resistance of low embodied energy cementitious composites for elevated temperature applications, such as fire walls and refractory materials. Use of Portland cement and refractory concrete in society accounts for a sizable amount of energy utilization due to the need for material manufacturing and transportation. Furthermore, Portland cement-based concrete does not perform adequately at elevated temperatures due to decomposition of the main strength-giving constituent, leading to costly repair and replacement. The research to be conducted in this project will promote the use of industrial byproducts in the construction and refractory industries, and therefore encourage further reductions in energy utilization associated with these sectors. The research outcomes of this project will be incorporated into high school teaching modules on materials relating to energy and the environment. In regards to promoting and encouraging underrepresented minorities in science, technology, engineering and mathematics, including young females, this project will enable high school and undergraduate interns to be trained in research during summers and over the academic year.The objective of this research project is to uncover and optimize the elevated temperature stability and carbonation resistance of chemically-activated cementitious composites, based on aluminosilicate chemistry, using a multifaceted experimental approach. Ambient temperature reaction kinetics and setting times will be investigated using ultrasonic analysis combined with isothermal calorimetry, where calcium-based additives will be utilized to control setting times and short-term mechanical behavior. The molecular structure of chemically-activated metakaolin- and fly ash-based pastes will be elucidated using X-ray pair distribution function analysis and infrared spectroscopy for a range of elevated temperatures, and the project will include the use of in situ carbonation/elevated temperature measurements at synchrotron facilities. Furthermore, given the susceptibility of cementitious materials to dehydration-induced cracking and loss of mechanical properties, the impact of alumina particle and fiber reinforcement on the microstructural (and atomic) behavior of the aluminosilicate composite will be uncovered using synchrotron and lab-based X-ray microtomography. Ultimately this project will generate the fundamental knowledge on the atomic and microstructural behavior of low embodied energy aluminosilicate cements at elevated temperatures, with the long-term aim of integrating this material into applications where conventional concrete quickly degrades due to exposure to high temperatures and aggressive chemicals.