Labo Magnel, the testing floor where innovations are born

From nanoscale to large setups, tests can be performed here on different scales. (large view)

From nanoscale to large setups, tests can be performed here on different scales.

(05-02-2020) 94 Years after the launch of Labo Magnel, it merges with other Ghent University labs and changes the name. Time to have a chat with Professor De Schutter!

Various departments and their labs at Ghent University merge into the Magnel-Vandepitte Laboratory for Structural Engineering and Building Materials—quite a mouthful! High time to discover the innovations that have been developed here over the years, the two men behind the double name, and the things that keep today’s researchers awake at night!

 

The godfathers of the laboratory

Gustave Magnel (1889–1955) was a specialist in reinforced and prestressed concrete and is considered a pioneer in experimental research on concrete constructions in Belgium. ‘That was one of his reasons for founding Magnel Laboratory’, says Prof. Geert De Schutter, head of the Department of Structural Engineering and Building Materials. ‘Concrete in itself is an “old” material known to the Egyptians, Greeks and Romans—plain concrete, of course. In the nineteenth century, however, it was rediscovered, so to speak, and many technical advances were made. So at the beginning of the twentieth century there was a strong need for further research on concrete, and Magnel wanted to meet this need with his laboratory.’

 

What about the name Vandepitte? ‘Daniël Vandepitte (1922–2016) was in many aspects Gustave Magnel’s successor. He also founded a laboratory, the Laboratory for Model Research, and just like Magnel he played a prominent role in the design of remarkable bridges. The first bridge made with continuous prestressed concrete girders was designed by Magnel, while Vandepitte created self-anchored concrete suspension bridges. Both were very innovative methods at the time!’

 

The core of the story

What is the essence of the laboratory now, the core of that they are doing? ‘Our motto is “Building[for]Humanity” or, in Dutch, “Mens[en]Bouw”. We want to contribute to an environment and a society with constructions that are safe and duurzaam. Now, the Dutch term duurzaam translates into English as both ‘durable’ and ‘sustainable’. These may appear to be similar terms, but they refer to different things. ‘Durable’ refers especially to the technical durability of materials and constructions. In other words, their resistance to environmental aggression, such as corrosion from seawater. ‘Sustainability’, in turn, refers to the environmental impact of materials. Producing Portland cement, for example, creates a lot of CO2, and we want to map possible alternatives. Are there other materials we can use to reduce the environmental impact of concrete? Or could we, conversely, make new concrete from building and demolition waste? Another pillar of our lab is the risk analysis of constructions. What happens when part of a construction disappears because of an accident, extreme weather conditions ...? Is there a redistribution of the forces or does the construction collapse? How can we make constructions more robust and prevent collapses? And what is the minimum amount of material we have to use for a construction to safely bear the planned load?

 

Not only has the Department of Structural Engineering and Building Materials led to different spin-offs, but Magnel Laboratory is also virtually the only university lab in the building sector that is accredited to perform tests for the industry and the government. For example, testing healing products, calibrating machines, and soon also testing anchorages in concrete ... ‘The earnings from these services pay for the maintenance of our lab equipment. It’s hard to squeeze money for this out of research budgets.’

 

From nanoscale to actual size, testing from small to big

Constructions and materials can be tested here, from nanoscale to large set-ups, and it shows. The first thing you see when you walk into the lab is a gigantic space 60 m deep, 15 m wide, and 8 m high. ‘For a long time it was one of the biggest testing floors in the world, but now there are much larger ones, like in China, with impressive shaking tables that imitate the effect of earthquakes. A grandiose sight!’

 

‘We collaborate very often with Tongji University in Shanghai. It’s China number-one university in the field of civil engineering. Our frequent collaborations have created a strong mutual respect. The Chinese may have a bad reputation for copying technologies and designs and for polluting a lot, but I see them making great efforts, for instance in the field of durability, and they also have a very innovative way of working. To give you an example, it is a widely known fact that the construction of the world’s tallest building, the Burj Khalifa, involved pumping concrete up to a height of about 600 metres, but in China they’ve managed to pump it a little bit higher. Our media don’t report this, however.’

 

To the left and right of the immense testing floor are numerous smaller rooms for measurement and tests. From a chemistry room for chemical analyses, a climate room with a constant temperature and level of humidity, over a microscopy room where paper-thin ‘slices’ of concrete are scrutinised, to workshops for working and sawing stone, for drilling in concrete ... All of this is very normal for a laboratory, but there are two objects that immediately catch the eye. One is a scale model of a huge cone-shaped building, the other a gigantic robot. ‘The cone is actually an alternative design by Magnel for the 1958 Expo. He proposed to build a concrete tower instead of the Atomium. With its antennas included, the tower would have stood ca.700 metres tall, which was huge for its time. The idea was to cover the whole of Belgium with this one antenna. We all know his design didn’t make it. Rumour has it there was a battle between the steel and concrete lobbies, but that’s an urban legend. The fact of the matter is that the cone, being mostly hollow on the inside, offered little usable space, whereas the Atomium with its nine spheres was much more functional.’ And the robot? ‘That’s actually a 3D printer with a reach of no less than three metres. 3D printing is relatively new to the building sector, but it offers many opportunities for further research. The big difference with 3D printing is that the printed material has to stiffen relatively fast because new material comes right behind. We’ve noticed that our 3D-printing tests often bring together researchers. There are always many curious onlookers, which is a good thing, because it shows researchers what their colleagues are up to and creates a dialogue.’

 

From theory to practice

What innovations are coming out of the lab now? ‘Too many to enumerate. Of course, as I indicated earlier, both Magnel and Vandepitte gave us remarkable discoveries and constructions. Nowadays we focus especially on expanding the possibilities of concrete as a material. We recently landed an ERC advanced grant to study the so-called ‘smart casting’ of concrete. This refers to when you’ve mixed concrete and it’s not liquid enough to work with. A good water/cement/admixture ratio is crucial for obtaining high-quality concrete. Finding the right ratio, however, is not a simple matter. It depends on several factors, such as the granulates you use, the binders ... The problem is that once the mix is made, you can’t put it back in the mixer and adjust the recipe. So we’re studying ways of adding new products to the mix, the so-called responsive polymers. As their name indicates, these are polymers that respond to, for example, electromagnetic signals and turn concrete more liquid again. This is called Active Rheology Control, and there’s also the opposite, Active Stiffening Control. That’s when you add polymers that make the concrete stiffer when they are exposed to certain signals. So far we’ve shown it can be done on a small scale; further research is needed to see if it can be applied large-scale.’

 

‘Another problem is that cracks sometimes appear in concrete. In itself this does not overly compromise the construction’s load-bearing capacity—the reinforcing steel almost completely deals with the force actions—but the cracks allow aggressive substances from the environment such as CO2 and chlorides to have a greater effect on the concrete and to quickly reach the reinforcement and attack it. Self-healing concrete, however, contains micro-organisms and super-absorbent polymers that make cracks seal themselves. This saves a lot of maintenance and repair costs.’

 

A 94-year oldie or the start of a new story?

What does the department head think the future holds for this laboratory after ninety-four years? ‘Our prospects for the future are excellent! Not only are we working with fantastic researchers, but I’m also very curious to see what innovations will emerge from our many lines of research. Also, the revamped Magnel-Vandepitte Laboratory makes it possible for us to more quickly move from theory to practice, which is exactly what we want, isn’t it?’

 

Any other interesting stories about Ghent University research? Let us know at techtransfer@ugent.be!

 


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