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

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.