Regular monitoring of critical infrastructures is essential at different stages of its life. Aging infrastructures and the risks it presents, like sudden collapse and failures require regular and efficient monitoring of its structural and health conditions to prevent this event from happening.
Acoustic emissions (AE) testing is an innovative, non-destructive, cost-effective method to monitor deterioration in assets. It can detect infrastructure damage like fiber breakages, friction, impacts, cracking, delamination, and corrosions before becoming serious.
The twi-global article explains how AE testing works:
“Acoustic emission testing works by mounting small sensors onto a component under test. The sensors convert the stress waves into electrical signals, which are relayed to an acquisition PC for processing. The waves are captured when the component is submitted to an external stimulus, such as high pressures, loads, or temperatures. As the damage grows in the component, there is a greater release of energy. The rates in which the acoustic emission is detected, the activity, and the intensity of the acoustic emission, the loudness, are monitored and used for assessing structural integrity and for health monitoring of components.
Acoustic emission can be thought of as tiny earthquakes that occur in the material. The technique globally monitors a component for defects, allowing large structures and machines to be monitored while in operation with minimal disruption, unlike destructive testing. By using multiple sensors, acoustic emission sources (and hence the damage) can be located.”
In the UK, Cambridge Centre for Smart Infrastructure and Construction (CSIC) partners with Highways England and Kier Group to improve deterioration detection assessments of highway assets. Through this partnership, the center can explore and seek ways to improve AE sensing technology’s monitoring highway assets.
The CSIC article reports that monitoring the structural condition of motorway bridges is done through periodic site inspections, a costly exercise and causes traffic disruptions that may be hazardous to road users.
The CSIC also wanted to integrate AE testing with improvements in computer and digital technology to take monitoring of infrastructure to the next level, “a systems integration approach that brings together multi-sensing systems, ICT, computer vision technologies, cloud data management, statistics, and big data analytics may oﬀer a better understanding of underlying deterioration and overall structural performance, enabling eﬀective structural alert systems for asset management.”
Although AE testing has been used in many applications like pipeline networks, composite vessels, and pressure equipment, its application for concrete bridges is fairly new.
AE will be used for early detection and 3D mapping of concrete cracks, particularly the bridge’s half-joints, the most critical part. This part of the bridge is also vulnerable to fatigue and moisture accumulation. Local failure can easily lead to the bridge’s partial or total collapse, making early detection crucial.
Early detection technologies like AE testing are significant breakthroughs in asset and infrastructure maintenance and bring many benefits.
Continuous improvements in AE testing technology combined with ICT and cloud data technology can open new possibilities for infrastructure management, monitoring, and analysis.