CAREER: Pickering Stability of Air Bubbles for Superior Air-Entrainment and Frost Durability of Cementitious Materials

该学院早期职业发展（CAREER）奖将支持研究，重点是改善应对气候变化迫切需要的具体可持续性的解决方案。虽然全球减少二氧化碳排放是必要的，但从2015年到2021年，水泥生产的二氧化碳排放量每年增加1.5%。2019年全球温室气体（GHG）排放量增长的三分之二归因于水泥生产。提高新混凝土结构的耐久性是减少温室气体排放的关键战略。虽然适当的引气对混凝土抗冻性至关重要，但传统的引气方法在现代混合物中往往无效。随着混凝土技术继续快速发展，以及传统混凝土的新替代品出现，需要一种更强大的空气夹带解决方案;一种可以克服已知的不利相互作用并可以适应日益复杂的系统的解决方案。这项工作将探讨的假设，皮克林稳定可以用来代替/除了目前的空气夹带方法特殊的气泡稳定性和尺寸控制，加速采用低碳建筑材料，而不牺牲其长期耐用性，从而可持续性。这项研究将被纳入K-12教育/推广（EO）计划，以丰富研究，教育和推广经验同时进行。EO计划的目标是培养一支多元化的、具有研究素养的员工队伍，他们可以利用自己独特的经验和观点，为变革引入创造性的、有影响力的解决方案。这项工作将通过研究整合的K-12教育和外展计划，一个本科生/研究生培训计划，重点是包容性教学法和社区建设的最佳实践，以及每年一次的混凝土职业周，将向8-12年级的学生介绍-通过与行业专业人士的设施图尔斯参观，从工作和5个其他具体的职业选择的研究经验。该项目将使用分子动力学（MD）模拟和实验来验证假设，并开发一个基本模型来描述控制水泥体系中气泡的Pickering稳定化的机制。研究教育活动的主要目标是制定一个强大的综合计划，重点是通过皮克林稳定开发空气夹带解决方案，同时推进STEM劳动力的研究素养，多样性和包容性。这项工作将为改善混凝土结构的抗冻性提供一个缺失但必不可少的基础，将工业界在混凝土中夹带空气的方式从试错式的经验做法转变为系统的，可控的，该奖项反映了NSF的法定使命，并被认为值得通过使用基金会的智力价值和更广泛的影响审查标准。

This Faculty Early Career Development (CAREER) award will support research that focuses on solutions for improved concrete sustainability that are urgently needed to combat climate change. While global reductions in CO2 emissions are necessary, CO2 emissions from cement production have increased 1.5% per year from 2015-2021. Two thirds of the global increase in greenhouse gas (GHG) emission in 2019 were attributed to cement production. Improving the durability of new concrete structures is a critical strategy for reducing GHG emissions. Although proper air entrainment is critical for concrete frost durability, conventional air entrainment methods are often ineffective in modern-day mixes. As concrete technology continues to develop at a rapid rate, and as novel alternatives to traditional concrete emerge, a more robust air entrainment solution is needed; one that can overcome known adverse interactions and can be adapted for increasingly complex systems. This work will explore the hypothesis that Pickering stabilization can be used instead of/in addition to current air entrainment approaches for exceptional bubble stability and size control, accelerating adoption of low-carbon building materials without sacrificing their long-term durability and thus sustainability. This research will be integrated into a K-12 education/outreach (EO) program to enrich research, education, and outreach experiences simultaneously. The goal of the EO plan is to develop a diverse, research-literate workforce that can leverage their unique experiences and perspectives to introduce creative, impactful solutions for change. This work will develop the workforce by building a diverse pipeline through a research-integrated K-12 education and outreach program, an undergraduate/graduate training program focused on best practice in inclusive pedagogy and community building, and an annual concrete career week that will introduce grade 8-12 students to hands-on research experience from the work and 5 other concrete career options via facility tours with industry professionals.The project will use molecular dynamic (MD) simulations and experiments to test the hypothesis and develop a fundamental model to describe the mechanisms controlling Pickering stabilization of air bubbles in cementitious systems. The main goal of the research-education activities is to develop a strong integrated program focused on developing air-entrainment solutions via Pickering stabilization, while advancing the STEM workforce in research literacy, diversity, and inclusion. This work will provide a missing, but essential foundation for improving the frost durability of concrete structures, transforming the way the industry entrains air in concrete from trial-and-error empirical practices to systematic, controlled, and predictable air entrainment via exploitation of fundamental principles.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.