Detection of corrosion-induced damage in reinforced concrete using NDT technology

• Main Author: Foo, Darren Sing Ching
• Other Authors: Fan Zheng, David
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2024
• Subjects: Engineering
• Online Access: https://hdl.handle.net/10356/177310
• Institution: Nanyang Technological University

Concrete is a fundamental building material renowned for its versatility and strength in construction applications. While plain concrete (PC) excels in compressive strength, reinforced concrete (RC) incorporates steel reinforcement to enhance its tensile strength and durability, making it a preferred choice for structural applications all around the world. Despite its advantages, RC structures are susceptible to corrosion, especially in aggressive environments such as marine settings or areas exposed to de-icing salts. Corrosion of the steel reinforcement within RC can lead to structural deterioration, compromising safety and longevity. The financial repercussions of corrosion-related damage to infrastructure, particularly highway bridges, are substantial. To mitigate these issues, early detection of corrosion in RC structures is crucial. Non-destructive testing (NDT) techniques offer a promising alternative, allowing for the evaluation of corrosion without damaging the concrete. Ground-penetrating radar has been proven effective in detecting severe corrosion damage. However, it remains challenging to access early-stage corrosion using GPR due to limited sensitivity to minor changes caused by corrosion and the influence of surrounding environment factors. To address this problem, this report presents a corrosion monitoring method using GPR. Corrosion-induced rust and cracks would alter the material properties surrounding reinforcing bars, leading to changes in the amplitude of reflections from the bars. Additionally, temperature variations also affect GPR signals due to changes in dielectric permittivity of material. To minimize the impact of temperature on early corrosion damage monitoring results, the Optimal Baseline Selection (OBS) method is employed. Subsequently, by analyzing the changes in the amplitude of reflections from reinforcing bars during the corrosion process, the development of corrosion can be determined. As a comparison, ultrasonic coda wave test was also conducted to monitor the corrosion conditions of the specimen. The results of each testing method were compared and cross-reference and was to agree with each other.