Determining the Location of Steel Reinforcement in Thick Concrete Walls by Non-Destructive Inspection

Concrete cover is the thickness of the concrete layer that protects the reinforcing steel bars (rebar) within a reinforced concrete structure. It acts as a barrier against external elements such as moisture, chemicals, and environmental factors, safeguarding the rebar from corrosion. Concrete cover measurement is performed by using various nondestructive tests such as GPS (Ground Penetrating Radar), electromagnetic test and ultrasonic. The main benefit of the concrete cover thickness measurement is to explain the causes of corrosion and identify areas that have the capability to corrode faster.

This paper discusses the possibilities to measure the concrete cover depth and determine the location of steel bars of a thick-walled concrete structure by using different nondestructive testing methods. The methods studied are a concrete cover meter, Ground Penetrating Radar, which is based on propagation radar waves in concrete, and Ultrasonic Pulse Echo tomography based on stress waves produced by ultrasonic pulses. The paper demonstrates the use of these methods for in-situ measurements on a thick-walled reinforced concrete structure. The concrete cover depth and the location for the reinforcement bars received by different methods are compared and the strong and weak points of the methods are discussed.

The results indicate that the concrete cover meter is suitable for measuring the thickness of concrete cover, while the Ground Penetrating Radar and the Ultrasonic Pulse Echo device were able to identify and locate the reinforcement bars position in the concrete structure.