Collaborative Research: Discovering Precipitation Pathways in Reactive Magnesium Oxide Cements via Nanoscale Interfacial Engineering for Durable Structural Composites

合作研究：通过耐用结构复合材料的纳米级界面工程发现活性氧化镁水泥中的沉淀途径

• 批准号: 2103056
• 负责人: Kemal Celik
• 金额: $ 25万
• 依托单位: New York University
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2021
• 资助国家: 美国
• 起止时间: 2021-06-01 至 2025-05-31
• 项目状态: 未结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=2103056&HistoricalAwards=false
• 关键词: Collaborative; Research; Discovering; Precipitation; Pathways

This collaborative research is focused on investigating and discovering magnesium oxide-based cement materials with strong mechanical properties for sustainable construction of civil infrastructure. Reactive magnesium oxide cement (RMC) is one of the most promising and environmentally friendly alternatives to ordinary Portland cement as a modern concrete binder. The advantages of RMC include low-cost and low carbon footprint compared to conventional cements. RMC achieves its strength by forming different magnesium carbonate phases as binding agents by reacting with carbon dioxide and water. However, the strength and durability properties of existing RMCs exhibit significant variations, slowing their adoption by construction industry. This research will address the following two technical challenges: (i) understanding the fundamental processes that govern the formation of dense magnesium carbonate phases using novel experimental testing and computer simulation; and (ii) innovation of durable RMC-based composites with high strength by incorporating corrosion-resistant micro- and macro-fibers. In this project, an outreach program for K-12, undergraduate, and graduate students will be implemented in order to disseminate knowledge on low-carbon structural materials for the construction industry, and train next generation students and engineers with sustainable infrastructure engineering backgrounds. The primary goal of this research is to tailor the carbonation products of reactive magnesium oxide cement by maneuvering thermodynamic and kinetic precipitation pathways in order to achieve high-performance RMC-based composites. RMC can be produced from low-temperature (500-1000 °C) calcination of either magnesite deposits or brucite precipitates from reject brine. Thus, it is deemed a more sustainable binder to ordinary Portland cement, whose production accounts for 7% of the global anthropogenic carbon dioxide emissions. Yet, the large specific volume variability of the different reaction products of RMC and the vulnerability of the embedded rebars to corrosion due to an absence or quick loss of the passivating oxide layer hindered its widespread application in the construction practice. To address these longstanding challenges, this research offers a combined experimental and computational research plan with two objectives: (i) to guide the nucleation and growth pathways via nanoscale interfacial energy considerations with non-reactive seeds (quartz, calcite, magnesite, and dolomite) to avoid the precipitation of low-density hydrated magnesium carbonate phases and hence reducing the volume change by modulating the competition between thermodynamics and kinetics driving forces, and (ii) to employ this fundamental knowledge to develop dense RMC-based fiber-reinforced structural composites that are less permeable and more resistant to cracking and corrosion. This approach exploits the fundamentals of the nucleation and growth process at the nanoscale, rather than case-by-case testing of different mix designs and processing conditions, to achieve robust composite performance.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.

这项合作研究的重点是调查和发现具有强大机械性能的氧化镁基水泥材料，用于民用基础设施的可持续建设。活性氧化镁水泥（RMC）作为现代混凝土粘结剂是替代普通波特兰水泥的最有前途和环境友好的材料之一。与传统水泥相比，RMC的优势包括低成本和低碳足迹。RMC通过与二氧化碳和水反应形成不同的碳酸镁相作为粘合剂来实现其强度。然而，现有RMCs的强度和耐久性表现出显着的变化，减缓了建筑业的采用。这项研究将解决以下两个技术挑战：（i）使用新的实验测试和计算机模拟来理解控制致密碳酸镁相形成的基本过程;以及（ii）通过加入耐腐蚀的微纤维和粗纤维来创新具有高强度的耐用RMC基复合材料。在该项目中，将实施针对K-12，本科生和研究生的推广计划，以传播建筑行业低碳结构材料的知识，并培养具有可持续基础设施工程背景的下一代学生和工程师。本研究的主要目标是通过操纵热力学和动力学沉淀途径来定制反应性氧化镁水泥的碳酸化产物，以实现高性能的RMC基复合材料。RMC可以通过菱镁矿沉积物或来自废弃盐水的水镁石沉淀物的低温（500-1000 °C）煅烧来生产。因此，它被认为是普通波特兰水泥的更可持续的粘合剂，普通波特兰水泥的产量占全球人为二氧化碳排放量的7%。然而，RMC的不同反应产物的大比容变化性和由于钝化氧化层的缺乏或快速损失而导致的嵌入式钢筋对腐蚀的脆弱性阻碍了其在建筑实践中的广泛应用。为了解决这些长期存在的挑战，这项研究提供了一个结合实验和计算的研究计划，有两个目标：（i）通过纳米级界面能考虑用非反应性晶种引导成核和生长途径（石英，方解石，菱镁矿，（二）避免低浓度的高浓度的低浓度的高浓度的高浓度的低浓度的高浓度的低浓度的高浓度的高浓度的致密水合碳酸镁相，并因此通过调节热力学和动力学驱动力之间的竞争来降低体积变化，以及（ii）利用这些基本知识来开发致密的基于RMC的纤维增强结构复合材料，该结构复合材料具有更低的渗透性和更高的抗开裂和抗腐蚀性。这种方法利用纳米级成核和生长过程的基本原理，而不是对不同的混合设计和加工条件进行逐个测试，以实现强大的复合材料性能。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。