Graduation Year
2025
Document Type
Dissertation
Degree
Ph.D.
Degree Name
Doctor of Philosophy (Ph.D.)
Degree Granting Department
Mechanical Engineering
Major Professor
Christopher Alexander, Ph.D.
Committee Member
Valerie Harwood, Ph.D.
Committee Member
Andres Tejada, Ph.D.
Committee Member
Micheal Cai Wang, Ph.D.
Committee Member
Ipek Yucelen, Ph.D.
Keywords
Bipolar Impedance, Microbiologically influenced, Post-Tensioned, Impregnation
Abstract
Corrosion remains a significant threat to civil infrastructure, resulting in costly repairsand potential structural failures. This dissertation addresses three critical aspects of corrosion: mitigation and monitoring of post-tensioned bridge tendons, and failure forecasting of wastewater force mains due to internal corrosion.
First, the research investigates the effectiveness of corrosion inhibitors (CIs) applied via pressure injection (impregnation) in post-tensioned tendons. The protective mechanisms and long-term performance of various inhibitors were evaluated to identify the most effective formulations. Among the tested inhibitors, MCI-2020 — a water-based, migratory, mixed-type corrosion inhibitor — demonstrated the most promising results, showing excellent corrosion protection while preserving the steel-grout bond integrity.
The second part of this study explores the use of bipolar electrochemical impedance spectroscopy (BPEIS) as a monitoring tool to assess the performance of impregnated corrosion inhibitors in post-tensioned tendons. The investigation also considered the minimum electrode size required to reduce contact impedance for reliable two-electrode BPEIS measurements. Results confirmed that BPEIS effectively distinguished the corrosion performance of different inhibitors and provided insight into their protective mechanisms, particularly their influence on the grout’s ohmic properties.
Finally, this dissertation addresses the prediction of wastewater force main failures using a simplified corrosion failure process model. The model revealed that, in the absence of cracks, corrosion of ductile iron does not initiate until complete deterioration of the mortar lining has occurred. Simulation results identified biochemical oxygen demand (BOD) as the most significant factor influencing mortar degradation rates. A case study analysis further suggests that force main failure can occur in as little as six years following the formation of an air pocket.
Scholar Commons Citation
Agbakansi, Stanley Chike, "Corrosion Mitigation and Monitoring of Bridge Tendons and Failure Forecasting of Wastewater Force Mains" (2025). USF Tampa Graduate Theses and Dissertations.
https://digitalcommons.usf.edu/etd/10914
