Imaging of Reinforced Concrete: State-of-the-Art Review

Abstract

Nondestructive evaluation plays an important role in the assessment of the nation's infrastructure. The evaluation methods for reinforced and prestressed concrete facilities can become more reliable if the methods incorporate imaging technology, which has been implemented widely in many fields. Radiography, ground penetrating radar (in B-scan mode) and infrared thermography have established themselves in civil engineering practice. They are used to nondestructively locate steel reinforcement and concrete flaws, such as delaminations, cracks and honeycombing. This paper discusses the principles of these established methods, as well as their advantages and disadvantages. Radioactive computed tomography, microwave holography, microwave tomography and acoustic tomography are in various stages of development. This paper summarizes the basis for each new method and the results of recent research. It also discusses the potential advantages of the new methods and the barriers to their implementation in civil engineering applications. Examples of images obtained with each technology are provided.