CAREER: Nanoscale Interfacial Phenomena and Reaction Kinetics of Calcium Silicate Minerals in Cements

职业：水泥中硅酸钙矿物的纳米级界面现象和反应动力学

• 批准号: 2237137
• 负责人: Alexander Brand
• 金额: $ 59.89万
• 依托单位: Virginia Polytechnic Institute and State University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2023
• 资助国家: 美国
• 起止时间: 2023-06-01 至 2028-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2237137&HistoricalAwards=false
• 关键词: CAREER; Nanoscale; Interfacial; Phenomena; Reaction

This Faculty Early Career Development (CAREER) award is to advance the understanding of portland cement reactions and mechanisms at the micro- and nanoscales. Portland cement is a critical material for civil infrastructure, with around 4 billion tons of cement produced annually worldwide, and the majority of cement is used as the binder in concrete, which is used to build structures, bridges, buildings, dams, roadways, ports, airfields, and other critical civil infrastructure. Despite the widespread application, the fundamental reactions and kinetics of how cement reacts with water to serve as the binder in concrete are poorly understood. This research studies two minerals in cements, tricalcium silicate and dicalcium silicate, which comprise around 75% of the cement composition. This study quantifies the fundamental kinetics and mechanisms that govern how tricalcium silicate and dicalcium silicate react with water at the nanoscale, which will provide new insights into the reactivity of cements. By understanding the fundamental hydration reactions in cements, the longer-term goal of the research is to develop high performance concrete that is more durable and sustainable, thereby ensuring improved resiliency and safety of American civil infrastructure. The experimental data from this award will be used to refine a kinetic Monte Carlo model of surface dissolution, resulting in a more robust model to gain insights into cement reactivity. An education component of the research will expand outreach to K-12 students through programs at Virginia Tech and at the Science Museum of Western Virginia to learn about cement and concrete, how cement reacts with water to make concrete, and the important role that concrete has in civil infrastructure. The primary challenge to understanding cement reactions with water is that there are a significant number of competing dissolution and precipitation reactions owing to a dynamic solution chemistry. The aim of this project is to simplify the problem by first understanding the reactions of specific minerals found in cements before scaling the complexity to systems with different solution compositions. Specifically, this study evaluates the real-time nanoscale dissolution rates of calcium silicate surfaces through in situ 3D surface topography measurements by spectral modulation interferometry. Coupled with additional characterization by X-ray reflectivity, X-ray photoelectron spectroscopy, and electron microscopy, these data will quantify the spatiotemporal variability of rate constants and define the mechanism through which a calcium silicate surface interacts with an aqueous solution. Subsequently, these data will be integrated into a kinetic Monte Carlo model of surface dissolution to yield a more accurate prediction of dissolution kinetics. The key contribution of this work is to advance new characterization techniques to accelerate the quantification and understanding of cement hydration, including the derivation of fundamental kinetic rates and mechanisms that can be integrated into computational materials science models of hydration. This contribution is significant because the data will revolutionize the understanding of how kinetic phenomena are involved in cement hydration, which will unlock new techniques or materials to rapidly advance towards improved sustainability in concrete materials.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

这个教师早期职业发展（CAREER）奖是促进波特兰水泥反应和机制在微观和纳米尺度的理解。波特兰水泥是民用基础设施的关键材料，全世界每年生产约40亿吨水泥，大部分水泥用作混凝土中的粘合剂，用于建造结构、桥梁、建筑物、水坝、道路、港口、机场和其他关键民用基础设施。尽管应用广泛，但人们对水泥如何与水反应以用作混凝土中的粘合剂的基本反应和动力学知之甚少。本研究研究了水泥中的两种矿物，硅酸三钙和硅酸二钙，它们占水泥成分的75%左右。这项研究量化了硅酸三钙和硅酸二钙在纳米尺度下与水反应的基本动力学和机制，这将为水泥的反应性提供新的见解。通过了解水泥中的基本水化反应，该研究的长期目标是开发更耐用和可持续的高性能混凝土，从而确保提高美国民用基础设施的弹性和安全性。该奖项的实验数据将用于改进表面溶解的动力学蒙特卡罗模型，从而产生更强大的模型，以深入了解水泥反应性。该研究的教育部分将通过弗吉尼亚理工大学和西弗吉尼亚科学博物馆的项目扩大对K-12学生的宣传，以了解水泥和混凝土，水泥如何与水反应以制造混凝土，以及混凝土在民用基础设施中的重要作用。理解水泥与水反应的主要挑战是，由于动态溶液化学，存在大量的竞争溶解和沉淀反应。该项目的目的是通过首先了解水泥中发现的特定矿物的反应来简化问题，然后将复杂性扩展到具有不同溶液成分的系统。具体来说，本研究通过光谱调制干涉法进行原位3D表面形貌测量，评估了硅酸钙表面的实时纳米级溶解速率。再加上X射线反射率、X射线光电子能谱和电子显微镜的额外表征，这些数据将量化速率常数的时空变异性，并定义硅酸钙表面与水溶液相互作用的机制。随后，这些数据将被整合到表面溶解的动力学蒙特卡罗模型，以产生更准确的溶解动力学预测。这项工作的主要贡献是推进新的表征技术，以加速量化和理解水泥水化，包括推导基本动力学速率和机制，可以集成到计算材料科学模型的水化。这一贡献意义重大，因为这些数据将彻底改变对水泥水化过程中动力学现象的理解，从而开启新技术或新材料，以快速提高混凝土材料的可持续性。该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。