Date of Award
2024
Document Type
Open Access Dissertation
Degree Name
Doctor of Philosophy in Civil Engineering (PhD)
Administrative Home Department
Department of Civil, Environmental, and Geospatial Engineering
Advisor 1
Qingli Dai
Committee Member 1
Zhanping You
Committee Member 2
Quang Tran
Committee Member 3
Trisha Sain
Committee Member 4
Zhen Liu
Abstract
The durability of reinforced concrete (RC) structures in chloride-rich environments is compromised due to steel reinforcement corrosion. This dissertation investigates chloride-induced corrosion in concrete containing supplementary cementitious materials (SCMs) and corrosion inhibitors through experimental and numerical methods.
First, the correlations between commonly used parameters and the chloride penetration resistance of concrete were investigated using matrix scatterplot analysis. Concrete samples with various binder types are tested. Results indicate that bulk resistivity is most related to chloride penetration resistance. The effect of SCMs on chloride binding was then studied, and an improved chloride profile prediction model was developed. The binding isotherm of concrete containing various SCMs was measured and further studied through thermodynamic modeling and X-ray diffraction (XRD) analysis. It is found that aluminum-rich SCMs increase chloride binding capacity, with an optimum replacement ratio. Simulations using the modified Nernst-Planck equation with variable diffusion coefficients demonstrated that considering non-linear binding improves the prediction accuracy of chloride ingress, aligning with NT Build 492 test results.
Additionally, the research explores the combined effects of FFA and sodium nitrate (SN) on rebar corrosion under natural conditions, adopting Fick’s second law to predict chloride concentrations at the steel-matrix interface. The predicted chloride concentrations profiles provide good estimation on the corrosion initiation time. Afterward, the effects of aforementioned FFA and SN on corrosion development under accelerated corrosion testing condition was studied by experiment and numerical simulation. Impressed current (IC) tests were conducted to induce corrosion with measurements of electrochemical parameters, steel mass loss, and rebar pull-out strength. Results indicate that FFA reduces the corrosion rate by enhancing pore structure, while SN delays corrosion by increasing chloride threshold levels. Numerical simulations depict crack initiation and development due to rust accumulation, and also link the steel mass loss to the strength reduction.
Overall, this dissertation provides insight into the understanding of chloride-induced reinforcement corrosion in concrete containing different additives, thereby contributing to a better design and maintenance of RC structure.
Creative Commons License
This work is licensed under a Creative Commons Attribution 4.0 License.
Recommended Citation
Su, Peifeng, "INVESTIGATING CHLORIDE INGRESSION IN CONCRETE AND CHLORIDE-INDUCED REBAR CORROSION", Open Access Dissertation, Michigan Technological University, 2024.