Explore 3D Imaging Technology Used to Reveal Defects Within Bridges

According to a study published on 9 May in IEEE Sensors Journal, one group of researchers at the China Research Institute of Radiowave Propagation has created a new radar device to ensure bridge safety. The new radar device can slip signals through the concrete of bridges to collect data and create 3D images of its interior.

Radar is considered a good method for noninvasive testing technology of bridge structures. Pulses can penetrate the surface and bounce back when they encounter changes in material density, so defects or voids in the reinforced concrete of a bridge can be found. However, there are also some challenges when using the technology to probe inside reinforced concrete. As the presence of steel mesh in bridges, a low-frequency radar technology may not be able to effectively penetrate the steel mesh to detect defects below it.

To solve this, the Chinese researchers developed a novel 3D ground-penetrating radar device that works at frequencies of 1.3 gigahertz which emits radar signals at a wide range of angles. The researchers’ data analysis system then translates the returning signals into 3D images of defects hidden behind the steel mesh.

The researchers also tested their device in the lab. In the experiment, a slab of reinforced concrete with known defects was used and the system detected defects. Not only that, the new 3D radar system generated 3D images up to 60 centimeters deep, via a portable device that boasts real-time imaging, despite the steel mesh in the bridge’s concrete structure.

However, while 3D imaging can provide a more intuitive visualization of steel reinforcement, identifying and distinguishing between different types of anomalies in the radar images can be challenging and it may require careful human judgment for identification. Therefore, the researchers also expect to adopt deep learning technology to analyze the images and provide automatic classification of defects in future work.

In addition to radar, other bridge-inspection techniques are currently used for assessing and monitoring the condition of bridge structures, such as visual inspection, ultrasonic testing, infrared thermography, or aerial inspection.

To ensure bridge safety, it is necessary to create new, convenient, efficient, and accurate nondestructive testing technologies and equipment to identify defects and weaknesses in the reinforced concrete components, which also play an important role in the quality and safety of a bridge.

Photo by Jerry Zhang on Unsplash