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The bridge was printed layer by layer in the concrete printing factory of Saint Gobain Weber Beamix and realised by the construction group BAM. It is not only the longest, but also the largest concrete bridge in the world for which the architect had complete freedom. Michiel van der Kley was able to work freely on the design and was not restricted by the material or traditional processes, such as concrete formwork.

Because the span is not constant everywhere and therefore the changing weight of the structure had to be taken into account, the choice was made to divide the bridge into printable parts. A parametric model – based on data – was used to generate the final design.

Faster and more flexible

In theory, printed bridges can be built much faster than ordinary bridges, with more flexibility and more room for personalised designs. They are also more sustainable, as less concrete is needed. The ambition of the partners in this innovative project is for 3D concrete printing to eventually become a sustainable construction method that can be used for the production of bridges and houses, among other things.

That is also the reason why Rijkswaterstaat, together with designer Van der Kley, took the initiative for this project. They donated this special bridge as a permanent reminder to the municipality of Nijmegen in honour of its election as European Green Capital 2018.

Unique bicycle bridge

The project is unique because the bicycle bridge has been designed with complete freedom of form, thanks to research at Eindhoven University of Technology and the further development of 3D concrete printing technology. The new appearance in de Geologenstrook park is characterised by its round and wavy shapes. 

Bas Huysmans, CEO of Saint Gobain Weber Benelux: “This 3D-production technique delivers savings of up to 50 percent in materials, because the printer only deposits concrete where it is needed for structural strength. 3D technology is maturing and is becoming a serious option for faster, more sustainable and cheaper construction of, for example, bicycle and pedestrian bridges.” 

Theo Salet, professor of Concrete Structures, TU Eindhoven: “The printing of concrete has enormous growth potential. We use less raw materials and can drastically increase the construction speed. In the future, we want to make concrete more sustainable and also reuse it. There is much more to achieve. I am also proud that the knowledge developed has found its way to the industry so quickly.” 

Alderman Bert Velthuis, Nijmegen City Council: “The city of Nijmegen is very honoured to receive this innovative 3D-printed bridge. We are a city of bridges, and this special, innovative bridge is a wonderful addition. The bridge leads to connection: in the design and construction phase it connected the different partners, and from now on the bridge connects our residents.”

Michiel van der Kley, designer: “I found it especially important to show where we stand with 3D-printing technology. The design is inspired by a shape that arises in nature because it has to absorb a certain force in the most efficient way, and now translated into a digital process. With this shape we have made 3D-printing of concrete objects more interesting again. ” 

The house
The house is a detached single-story home with 94 square meters of net floor area, a spacious living room and two bedrooms in the Eindhoven neighborhood of Bosrijk. The home is shaped like a large boulder, which fits in well with the natural location and nicely demonstrates the freedom of form that is offered by 3D concrete printing. Thanks to extra thick insulation and a connection to the heat grid, the home is highly comfortable and energy efficient, with an energy performance coefficient of 0.25.

Freedom of form
The partners deliberately set the bar high by designing the house in the shape of an irregular boulder. In recent years, the necessary R&D has been done to make concrete printing possible in all sorts of forms. It was especially challenging to print the inclining walls but this has now been mastered by the project’s participants. With the knowledge gained, the door has been opened to a completely different kind of construction to the usual rectangular houses.

Quick & sustainable
In principle, printed homes can be built a lot faster with more flexibility and personalized designs. Additionally, this is more sustainable as less concrete is needed. The ambition of the Project Milestone partners is for 3D concrete printing to eventually become a sustainable construction method that contributes to solving the housing shortage.

The next homes
The five houses of Project Milestone are being built one after the other so that each new round of construction can maximize the learning opportunities from the previous. Soon, the project partners will begin work on the design of the next homes, which will have multiple floors and therefore require further development of the technique.

The construction method
The house consists of 24 printed concrete elements which were printed layer by layer at the printing plant in Eindhoven. The elements were transported by truck to the building site and placed on a foundation. The house was then provided with a roof and frames, and the finishing touches applied.

The parties and the collaboration
A distinctive feature of the project is the ‘Triple Helix’ collaboration between the government, knowledge institutions and industry. The municipality was a co-initiator, booster of innovation and facilitator of the project. TU/e conducted research and developed models to enable 3D concrete printing, Saint-Gobain Weber Beamix developed the special types of concrete mortar needed for 3D printing, and they worked together to develop the printing technology. Witteveen+Bos worked on the building engineering and structural aspects. Construction company Van Wijnen led the project and built the house. The house is now owned by residential real estate investor Vesteda, which rents it out to private individuals.

Yasin Torunoglu, alderman for housing, neighborhoods, work and spatial development, Municipality of Eindhoven
“Innovation is an important pillar in construction. In addition to affordable homes, the market increasingly demands innovative housing concepts. With the 3D-printed home, we’re now setting the tone for the future: the rapid realization of affordable homes with control over the shape of your own house. Innovation and discovery with an eye for design is in Eindhoven’s DNA. We don’t do it alone here but together. I’m proud that this promising innovation has a place in our city and, more importantly, that it provides people with an affordable home.”

Theo Salet, Professor of Concrete Structures, Eindhoven University of Technology
“With this small building, a first major step has been taken today in the development of construction into a high-quality manufacturing industry. From design to implementation, digitalization leads to sustainable and affordable homes tailored to the wishes of the occupant. I’m proud that the knowledge we’ve developed at TU/e has led to this innovation by industry, with the help of the municipality, within a short timeframe.”

Bas Huysmans, CEO of Weber Benelux
“With the printing insulated and self-supporting wall elements curved in three planes, we’ve taken important steps in this project in the further development of 3D concrete printing in construction. Together with all partners, we’ve completed a challenging process and realized a very special home. I think that we’ll soon be able to proudly add the Milestone houses to the list of iconic projects in Eindhoven.”

Erwin Kersten, Regional Director South, Van Wijnen
“With the realization of this first Milestone home, Van Wijnen has once again demonstrated its leadership in the field of industrialized construction. Together with our partners in the chain, we’re constantly looking for new techniques and material applications that contribute to sustainability and affordability. Innovations like Project Milestone are enormously important to this.”

Steven Delfgaauw, Business Unit Manager Buildings at Witteveen+Bos
“Today, we’re taking an important step towards a construction chain in which it is possible to realize the sustainable house of your dreams within a short period of time. Our team of structural engineers, construction experts and building physicists, in cooperation with the partners, have delivered a world-class achievement by realizing a design that complies with all the building regulations. We have learned a lot from this and have also gained new insights. We can’t wait to use this experience to take the next steps in the development of concrete printing.”

Pieter Knauff, Chief Investment Officer, Vesteda
“3D concrete printing’s freedom of form creates an enormous new scope of possibilities in the design and experience of a home. At the same time, this new technique contributes to the required sustainability in the construction industry, the acceleration of building production and the control of construction costs, which is much needed in order to continue building affordable homes.”

Sadly, most of the new arriviste in 3D printing houses can best be described as fantasts, con men and/or dangerously silly people. We know of over a dozen projects that have made claims that are plainly false. Other have claimed things that are literally impossible and fantastic while for yet others I’d veer more into hallucinatory as an apt descriptor. I’m not sure why 3D printing houses, in particular, attracts a disproportionate number of P.T. Barnum types. Perhaps just like selling the Brooklyn bridge was an inescapable fantasy for some, 3D printing homes is a dream huge enough to hold their egos and ambitions. Alas, 3D printing, the technology to let anyone make anything, has always attracted a disproportionate amount of sociopaths. 3D printing buildings, however, could become a support group.

The same bedrock of a possible future that will change everything by altering the very substance of all of the things, underpins the naive, regularly ambitious and the very many good people we have in 3D printing. On the whole, we are set to make a positive impact on the world, (barring the very real possibility of a 3D printed ICBM making a rather negative impact on our karmic balance sheet). We are set to revolutionize industries and potentially make all of the things better (and perhaps even more sustainable). Supply chains will be cut down to only a few links, 100’s of parts will become 3, spare parts for people will be made and if anyone ever gets a mortgage on Mars it will because of 3D printing. None of the important things will ever be the same due to the 3D printed future that we are inventing today. Eventually. The great and good will hum along like a DTM Sintertation, we will get there in the end. I love the aroma of crystallizing polyamide in the morning; smells like victory.

What I also love is clipboards and compliance people. Anyone can dream a house, make some idiotic rendering or lie on TV but only a few people actually have the wherewithal to make an actual house with 3D printing. Perhaps the people at BAM Weber Beamix could make this happen.

BAM is one of the largest construction groups in the Netherlands. The 7 billion euro construction company builds commercial real estate, houses, roads, football stadiums and much else besides. Saint-Gobain Weber Beamix is a construction supplies company that makes concrete, tiles and any stuff you can stick to a building or a bridge. They’re a part of Saint Gobain, a $39 billion revenue French construction materials company. Another partner is Bekaert a $5 billion dollar metal wire company that makes any and all kinds of steel wires and coatings. Other partners include 1100 engineer strong engineering consultancy firm Witteveen+Bos and Van Wijnen a company that cannot really explain what it does on its website but it seems building related or perhaps they’re the sociology department of the local university. Speaking of the local university, the Technical University of Eindhoven is also a partner. These partners together have made a 3D printed bicycle bridge in nearby Gemert and will be 3D printing five residential homes in Eindhoven.

Now they’ve opened a “3D printing house factory. A “commercial industrial location for 3D printing concrete components for construction.” The consortium says that they will work “larger, faster and more efficiently” and are working to “scale up the technology.” The consortium has already received four orders, all bicycle bridges that will be 3D printed for the Province of North Holland. The factory will also be used for the five residential homes in Eindhoven, Project Milestone. They anticipate that they will increase “design freedom” and be able to use “less concrete with the same final results.” Efficiencies will reduce waste, CO2 and they will “no longer need formwork.” They also state that “they expect construction to be sped up, the margin for error to be reduced.” All parties will “look at the same design” and deal with the same changes which will lead to reduced error rates.

The team also mentioned that they would be open to partners and ideas from potential partners but for them “printing a house would be a big step.” Bas Huysmans of Weber Beamix stated that “we’re at the point where we can 3D print in a commercially sustainable way.” He pointed out to prefab bridge elements and house parts that could be made now. He also said that “the dream that you can come with your USB stick (or built in chip)…to a site and that then in a number of hours your building can be printed will at one point become real” but that the consortium “was not there yet.” When Henk Post of Bam was asked if this would be “the construction technology” he qualified that and said that it would be one of the construction methods of the future albeit an important one.

What I liked most about the interviews and the press releases was the fact that consortium participants qualified their answers and seemed above all to be interested in safety and realism. That really gave me a good feeling about this announcement. Apart from that the fact that the Bam Weber 3D printer is attempting to reinforce their 3D prints with polymers and metal wires to increase the strength of their parts also tells me that they seem to be further along than other 3D printing house initiatives. Most others are ignoring reinforced concrete which is essential for all the crazy stuff they say they want to build.

You can watch a video here (in Dutch) showing you the 3D printer in action, another video showing you the process is below.

It is also notable that the consortium seems to think that the dream of 3D printing homes is to do it on location. They seem to consider the factory an interim step. Indeed printing on location would save considerably on transport costs but it would entail moving the printer every time and having to deal with the elements. We saw that this in particular causes problems for house 3D printing with moisture, water and temperature fluctuations wreaking havoc on results. We saw this with our own eyes when in 2017 the US Army found it doable to 3D print a Barracks in a day inside. Meanwhile a year later our reporter Sarah Saunders was there when a new outdoor 3D printing attempt went awry through the weather. We loved the US Army’s openness and their weather-related problems only made us believe that other people were not being as forthright.

In 3D printing, we already know that by eliminating environmental influences we significantly improve our repeatability, reliability, and results. What will that mean for a building as it is heated by the sun during the day or what happens when the morning dew or a rainshower gets trapped in a layer? Or what happens when a stray leaf gets trapped? What happens when sections below dry at different rates due to changes in humidity or ambient? Will we get weaker in layer adhesion with ambient temperature fluctuations or increased wind flowing over the structure? No one has sufficiently been able to explain these issues away for me yet. So the idea of having an indoor 3D printing factory to me sounds like an excellent way to get more process control and print houses with fewer problems in them. Of course, 3D printing on location is the dream but perhaps producing houses or large parts of houses indoor in factories will become the reality? In any case, slow and steady wins this race. Patience, young grasshoppers.