Special: Nijmegen now has the world's longest 3D concrete printed bicycle bridge

The further development of 3D concrete printing technology seems to be gaining interesting momentum. On Wednesday afternoon, September 8, proof of this tantalizing innovation was provided once again, this time in Nijmegen. For there stands the longest 3D concrete printed bicycle bridge in the world. The bridge was printed layer by layer in the concrete printing plant of Saint Gobain Weber Beamix in Eindhoven. 

At the factory, pride naturally prevails. Marketing Manager Marco Vonk and International 3D Project Manager Peter Paul Cornelissen say, "You often see with new technologies that it's a hype. But 3D concrete printing is definitely going to have a fundamental place in the industry. We are only at the beginning of this gray revolution!"

First, back to the bridge in Nijmegen. This is the longest, printed concrete bridge in the world where the architect had complete freedom in the design phase. Therefore, during the design process he was not hindered by the material or the traditional processes, such as the concrete formwork. The architect was completely free to do as he pleased. Because the span of the bridge is not constant everywhere, and thus the changing weight of the structure had to be taken into account, it was decided during the printing process to divide the bridge into printable parts. Based on data, the final design was finally created.

Personalized

"The great thing is that printed bridges can ultimately be built a lot faster than regular bridges," says Marco Vonk. "And that's good news. Because, time is money. Also, because of this working process, there is more flexibility and more room for personalized designs. So you can do more custom development. That should sound like 'very interesting' to the market, it seems to me. In addition, these concrete bridges are more sustainable because less concrete is needed. It's really that simple." 

Sustainability

Peter Paul Cornelissen adds: "I think that with regard to the theme of 'sustainability' we are in the spirit of the times. It has really sunk in at all levels of society that we can no longer lay unbridled claim to scarce resources. Sustainability is not a fad, but has become an essential part of the business operations of many companies. The market is asking for it because everyone wants to take responsibility for the future of our planet. This is precisely why I am 100% sure that we are actually only at the beginning of the 3D concrete printing revolution with all those sustainability benefits mentioned. Also for that reason, it is indeed something to be proud of that we were partly behind what has now been delivered in Nijmegen." 

Smaller carbon footprint

The twosome from Saint Gobain Weber Beamix are happy to explain how the carbon footprint in such projects is getting smaller and smaller in the ongoing development. "With our 3D printer, we make the elements hollow instead of solid. As a result, much less mortar is needed. Moreover, we can eliminate the demand for rebar. It makes the footprint sometimes only half compared to traditional precast concrete. I expect that - given rapid technological developments - this will already be heading toward just one-third!"

So the sustainability benefits are many. Marco Vonk is convinced that Weber Beamix will use the Eindhoven concrete printer for many other contractors in the coming months and years. Growth is on the horizon. Appreciation is logical also within the entire group, which operates in as many as 70 countries. One sees well what innovative power there is at the moment in the Eindhoven plant. "I think every day people look curiously at us to see how we develop our innovative strength and manage to put it into practice," says Peter Paul Cornelissen.

"However, we are far from being there, of course. It's an ongoing process. Innovation is not a 1-day-business thing. Of course, supplying the special mortars to sister companies is not a problem. Bagged dry mortar, the product everyone knows us by, easily goes around the world. But we also have to supply knowledge about processing, mixing, pumping and printing. We have that expertise. In fact, I would venture to say that Eindhoven has become the epicenter of concrete printing and that from here we will really act as a global knowledge center for Saint Gobain. And, for the rest of the market."

Tomato ketchup

For example, what is unique about Weber Beamix's mortar is that it does not use accelerators, but thixotropic properties. "Many companies that print with concrete work with accelerators, so the concrete starts curing almost immediately after leaving the nozzle. This can cause considerable heat generation, which when cooled quickly leads to shrinkage and cracking. Our mortar is quite stiff by itself, but it liquefies when you add energy by pumping, shaking or vibrating. Compare it to a bottle of tomato ketchup. If you hold it upside down and shake it vigorously for a while, you break the shear stress. It liquefies and it lands on your plate. But as soon as the mortar settles down, it becomes stiff and consistent again. And then the hydration of the cement has yet to get going!"

So the two know what they are talking about. And that is not illogical. After all, the company was already experimenting with concrete printing in the late 1990s. Perhaps it was still seen as a "hobby" back then, but by 2005 a 15-centimeter thick wall over 2 meters high had already been printed. And ... a lot of knowledge had been created especially about mortars that you could apply wet in layers on top of each other. When Eindhoven University of Technology started the 3DConcrete Printing research program in 2015 AND installed a concrete printer, the collaboration with Beamix to develop the right mortar was quickly established. 

The rest is history. Just look at the beautiful bridge in Nijmegen, which with certainty can now be considered the most current proud reference project and from which new inspiration can definitely be drawn. 

The bridge can be found in Dukenburg Park. 

Learn more at www.3d.weber