CAREER: Towards Perpetually Limited Corrosion of Steel in Concrete with Tailored Interfaces

该学院早期职业发展（Career）奖将支持旨在最大限度地提高钢筋混凝土基础设施的可持续性和耐久性的综合研究和教育重点。钢的腐蚀仍然是钢筋混凝土耐久性的一个限制因素，并阻碍了使用新的和其他耐用的消耗二氧化碳的水泥和混凝土。该项目将确定最佳的钢和混凝土界面条件，可以永久限制氯化物影响的腐蚀损害，同时考虑传统和可持续的替代混凝土混合物配方。研究工作将与教育目标相结合，以提高土木工程学生和从业人员解决土木基础设施中经常被忽视的腐蚀耐久性问题的能力。高中生的研究经验将用于提高代表性不足群体对STEM职业的兴趣。腐蚀损害预测模块通过国际公认的腐蚀组织传播和管理，将为土木工程从业人员提供知识基础和技能，以确保土木基础设施的耐久性。研究目的是在考虑钢-混凝土界面条件的情况下，表征混凝土内部钢腐蚀的多尺度演化。腐蚀开始于小的、局部的凹坑，这些凹坑可以生长并积累成更广泛的腐蚀损伤。然而，在某些条件下，凹坑可以通过再钝化过程停止生长。该项目旨在：1)确定促进氯化物引起的点蚀再钝化所需的钢与混凝土界面条件；2)建立控制坑形演变和损伤进展的机制；3)基于暴露试验结果校准的多尺度损伤预测模型，确定最佳抗腐蚀界面条件。界面条件促进局部凹坑再钝化的能力将根据由单凹坑生长实验测量的凹坑稳定性系数来量化，该实验考虑了由水分水平和粘合剂配方的多孔反应性质引起的阴极限制。考虑到钢和混凝土界面的质量，劈裂双极电化学耦合多物理模型将产生坑生长动力学和形状演变。一个多尺度腐蚀损伤预测模型，可以模拟局部点蚀到宏观尺度腐蚀损伤的转变，将用于提供考虑传统和新型碳汇混凝土配方的最佳界面条件，从而最大限度地提高腐蚀耐久性。这项工作的结果将有助于制定基于性能的规范，用于设计钢筋混凝土基础设施的永久有限腐蚀。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 Faculty Early Career Development (CAREER) award will support integrated research and education thrusts aimed at maximizing the sustainability and durability of reinforced concrete infrastructure. Corrosion of steel continues to be a limiting factor in the durability of reinforced concrete and has prevented the use of novel and otherwise durable carbon-dioxide consuming cement and concrete. This project will identify optimal steel and concrete interface conditions that can perpetually limit chloride influenced corrosion damage considering both traditional and sustainable alternative concrete mixture formulations. The research effort will be integrated with an education goal to improve the ability of civil engineering students and practitioners to address often overlooked corrosion durability issues in civil infrastructure. Research experiences for high school students will be used to enhance interests in STEM careers among underrepresented groups. Corrosion damage forecasting modules disseminated and administered through an internationally recognized corrosion organization will provide a knowledge foundation and skill set to civil engineering practitioners tasked with ensuring the durability of civil infrastructure.The research objective is to characterize the multi-scale evolution of steel corrosion within concrete considering the condition of the steel and concrete interface. Corrosion starts as small, localized pits that can grow and accumulate into more widespread corrosion damage. However, under some conditions the pits can stop growing by the process of repassivation. The project aims to: 1) identify steel and concrete interface conditions required to promote repassivation of chloride-induced pitting corrosion, 2) establish the mechanisms controlling pit shape evolution and damage progression, and 3) identify optimally corrosion resistant interface conditions based on multi-scale damage forecasting models calibrated to exposure testing results. The ability of the interface condition to promote repassivation of localized pits will be quantified according to pit stability coefficients measured by single pit growth experiments accounting for cathodic limitations due to moisture levels and the porous-reactive nature of binder formulations. Split bipolar electrochemistry coupled with a multi-physics model will yield pit growth kinetics and shape evolution considering the quality of the steel and concrete interface. A multi-scale corrosion damage forecasting model that can simulate the transition of localized pitting corrosion to macro-scaled corrosion damage will be used to inform optimal interface conditions that maximize corrosion durability considering traditional and novel carbon-sequestering concrete formulations. The results of this work will enable the development of performance-based specifications for the design of perpetually limited corrosion of reinforced concrete infrastructure.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.