CMMI-EPSRC: Response to CO2 Exposure of Concrete with Natural Supplementary Cementitious Materials (RENACEM)

该奖项由NSF 18-067， NSF工程- ukri工程和物理科学研究委员会资助。混凝土是美国用途最广泛的建筑材料，用于建造和维修建筑物、运输系统和能源基础设施。混凝土基础设施的开发、维护和维修对国家增长、繁荣、公民安全和福利至关重要。混凝土是一种复杂的复合材料，由矿物骨料、水、硅酸盐水泥和添加剂混合而成，这些添加剂在混合时产生的初始流体和最终硬化状态下增强其性能。大多数现代混凝土混合物含有补充胶凝材料（SCMs），部分取代波特兰水泥，以提高混凝土的长期耐久性，降低成本，并减少与混凝土生产相关的二氧化碳排放。最常用的scm是废物来源，特别是燃煤电厂的残灰。然而，工业过程的变化和对scm需求的增加导致高质量、废物来源的scm短缺。天然SCMs，如煅烧粘土和火山矿物，是废物来源的SCMs的有希望的替代品，其使用量正在增加。天然SCMs的优势在很大程度上源于它们的化学和矿物学；它们比废物来源的材料更均匀，这有助于质量控制。此外，它们还提供经济、环境和性能方面的好处。然而，SCMs的使用也有缺点，即倾向于增加混凝土与大气中的CO2之间的化学碳化反应，这可能导致钢筋腐蚀，强度损失和开裂。因此，重要的是要更好地了解含有天然SCMs的混凝土中的碳化过程，以便确定在不牺牲性能的情况下带来好处的材料和混合物。通过结合美国和英国机构之间的研究专长和资源，该项目将研究含有新的和有前途的天然scm和二氧化碳来源的混凝土之间的相互作用，测试和损伤检测的新方法，以及减少退化影响的新策略。这项研究将有助于生产出高质量、低环境影响的混凝土。因此，这项研究可以对混凝土基础设施的寿命和可持续性产生广泛的影响，这对全球基础设施、可持续性和劳动力发展至关重要。国家繁荣取决于全球可持续的资源利用和保护方法。参与该项目的学生将获得宝贵的国际研究经验。考虑到建筑领域在混凝土中越来越多地使用天然SCMs，了解天然SCMs对碳化降解的贡献对于该技术的可行性至关重要。此外，操纵系统的组成来减少或防止碳酸化是可能的，但以前没有探索过。使用天然补充胶凝材料的混凝土的二氧化碳暴露响应（RENACEM）项目是美国和英国的联合合作项目，由德克萨斯大学奥斯汀分校、利兹大学和谢菲尔德大学的研究人员组成，旨在阐明控制天然胶凝材料生产的混凝土长期性能的基础科学。该项目将调查混凝土与大气中二氧化碳及其运输之间的化学相互作用，以确定有意义的评估方法。这将支持采用新的方法，用天然SCMs和新的预测模型来测试混凝土的碳化。RENACEM包括五个工作包（WPs）。WP1将专注于天然SCMs的高级表征和降低碳化敏感性的材料的开发。WP2将建立控制天然scm基材料碳化的物理化学机制，将它们的矿物学、相组合和微观结构与它们对自然和加速碳化的响应联系起来。WP3将使用先进的光纤传感网络，对天然scm基混凝土暴露于二氧化碳后的pH值和相对湿度变化进行现场监测。WP4将超越碳化建模的最先进水平，为碳化速率和程度带来新的预测能力，包括使用中的混凝土吸收二氧化碳的总程度。最后，WP5将重点关注项目管理，包括风险和进度评估，以及计划影响活动的实施。该奖项反映了美国国家科学基金会的法定使命，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。

This award is supported under the NSF 18-067, NSF Engineering-UKRI Engineering and Physical Sciences Research Council, funding opportunity. Concrete is the most versatile building material in the United States, used to construct and repair buildings, transportation systems, and energy infrastructure. The development, maintenance, and repair of concrete infrastructure is vital to national growth, prosperity, citizen safety, and welfare. Concrete is a complex, composite material, made of a mixture of mineral aggregates, water, portland cement, and additives that enhance its properties in the initial fluid generated upon mixing and in its final hardened state. Most modern concrete mixtures contain supplementary cementitious materials (SCMs) that partially replace portland cement to improve concrete long-term durability, lower costs, and reduce CO2 emissions associated with concrete production. The most commonly used SCMs are waste-derived, especially residual ashes from coal-fired power plants. However, changes in industrial processes and increasing demand for SCMs are leading to a shortage of high quality, waste-derived SCMs. Natural SCMs, such as calcined clays and volcanic minerals, are a promising alternative to waste-derived SCMs, and their use is rising. Advantages of natural SCMs stem in large part from their chemistry and mineralogy; they are more homogeneous than waste-derived materials, which aids in quality control. Moreover, they also provide economic, environmental, and performance benefits. The use of SCMs, however, also has a downside, i.e., the propensity to increase chemical carbonation reactions between the concrete and atmospheric CO2, which can result in corrosion of steel reinforcement, loss of strength, and cracking. Therefore, it is important to develop a better understanding of the carbonation processes in concrete containing natural SCMs in order to identify materials and mixtures that that impart benefits without sacrificing performance. By combining research expertise and resources between institutions in the United States and the United Kingdom, this project will investigate interactions between concrete containing new and promising sources of natural SCMs and CO2, new methods of testing and damage detection, and new strategies to minimize the impact of the degradation. This research can lead to the production of higher quality, lower environmental-impact concrete. As such, this research can have a broad impact on the lifespan and sustainability of concrete infrastructure, which is critical for infrastructure globally, sustainability, and workforce development. National prosperity depends on a global, sustainable approach to resource utilization and protection. Students working on this project will gain valuable international research experiences. Considering that the construction field is increasing its use of natural SCMs in concrete, understanding the contribution of natural SCMs toward carbonation degradation will be critical for the viability of this technology. Furthermore, manipulating the composition of the systems to reduce or prevent carbonation is possible, but has not previously been explored. This Response to CO2 Exposure of Concrete with Natural Supplementary Cementitious Materials (RENACEM) project is a joint United States-United Kingdom collaboration among researchers at the University of Texas at Austin, University of Leeds, and University of Sheffield to elucidate the fundamental science controlling the long-term performance of concrete produced with natural SCMs. This project will investigate the chemical interactions between concrete and atmospheric CO2 and its transport to identify meaningful methodologies for their assessment. This will underpin the adoption of new methods for testing carbonation of concrete with natural SCMs and new predictive models. RENACEM comprises five work packages (WPs). WP1 will focus on advanced characterization of natural SCMs and the development of materials with reduced carbonation susceptibility. WP2 will establish the physicochemical mechanisms governing carbonation of natural SCM-based materials, interlinking their mineralogy, phase assemblages, and microstructure with their response to natural and accelerated carbonation. WP3 will investigate in situ monitoring of pH and relative humidity changes upon CO2 exposure of natural SCM-based concrete using advanced fiber optic sensing networks. WP4 will move beyond the state of the art in modeling of carbonation to bring new predictive capabilities for both carbonation rate and extent, including the total extent of CO2 uptake by concrete in service. Finally, WP5 will focus on project management, including risk and progress assessment, and implementation of planned impact activities.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.