06 December 2019

Globally, corrosion is an enormous problem. It is
estimated that approx. USD 2.5 trillion (approx. EUR 2.3 trillion) is spent
annually on remediating rust problems, amounting to about 3-4% of the GWP.
Researchers from the Department of Engineering, Aarhus University, are
developing a cheap, intelligent, self-powered, built-in patch that continuously
monitors corrosion and steel reinforcement integrity in concrete structures.
The goal is simple and cheap structural health monitoring everywhere.

In August 2018, the once-proud engineering legacy
of Italy was dealt a major blow when the one-kilometre-long and 45-metre-high
Morandi bridge collapsed and killed 43 people. 600 were left homeless.

While the exact cause of the collapse has yet to be
determined, investigators have found evidence that undetected corrosion and
structural deterioration were to blame for the tragic event.

The Italian case of the Morandi bridge is not
unique. Corrosion can be a huge safety hazard all over the world if not
properly managed and monitored. But despite the major global challenges with
corrosion in steel-reinforced concrete structures, there are currently only few
possibilities to actually monitor the problem: the sensors being used for rust
monitoring today are indicative, can be error-prone and are based on slow,
energy-demanding technology that is more than half a century old and which
costs up to EUR 5,000 per measuring point.

Researchers from Aarhus University are aiming to
change all this. In a collaboration project with the technological service
company FORCE Technology, they are developing a brand new, intelligent and
self-powered sensor.

“The aim of this project is to develop a
plaster sensor which is placed on the reinforcement and moulded into the
concrete construction. The sensor and interfacing electronics are powered by
means of energy-harvesting technologies to ensure continuous monitoring of the
condition of the steel,” says Jaamac Hassan Hire, industrial PhD student
on the project.

The data collected is sent to a central computer
where it is processed. The project, named DIGIMON, is being headed by Associate
Professor Farshad Moradi, Department of Engineering, Aarhus University:

“Within this project, we will use ultrasonic
waves generated locally in a self-powered sensor inside the concrete to monitor
the corrosion. We want to be among the first – probably the first-ever – to
develop a self-powered corrosion sensor,” Farshad Moradi adds.

The project has been funded by Innovation Fund
Denmark as a collaborative industrial project between ICELab at Aarhus
University and IdemoLab at FORCE Technology.

“We’re happy to be a part of this project.
We’re working with monitoring today, and we see a lot of potential in being
able to continuously monitor large constructions, even in harsh environments.
This would provide us with a clearer picture of the state of the construction
or building. DIGIMON is a great example of mobile and energy-efficient modern technology
that’s at the very front of the technological revolution, and I hope it can
play its part in making structures safer in the future,” says Morten
Wagner, head of department at FORCE Technology.

However, there is no getting away from rust. The
harsh marine environment to which steel-reinforced bridges are exposed, for
example, causes a spontaneous electrochemical process known as oxidation.

The problem has attracted increasing international
focus and has created a huge need to increase monitoring of newly constructed
infrastructure. It is estimated by NACE International that up to 35% of the
cost of corrosion could be realized.

“It’s extremely interesting to work on this project. Structural health monitoring is a new and improved way of doing traditional non-destructive testing. It involves the integration of sensors, smart materials, data transmission and processing. It’s currently receiving great technical and scientific interest, since awareness of structural integrity and safety, planning of repair works and the associated costs have become a focus area for owners. We hope that, through this project, we can bring the technology into a viable industrial application, benefitting society both in terms of safety and economically,” says Jaamac Hassan Hire.

Read the latest issue

Latest Issue