In 2015, the Eindhoven University of Technology (TU/e) in the Netherlands began developing a giant concrete 3D printer as part of a large-scale research project. The massive 3D printer, which includes a concrete mixing pump and is constructed of a four-axis gantry robot with a print bed of approximately 9.0×4.5×3 m3, was introduced last summer at a public demonstration when it was used to 3D print a pavilion on the university’s campus. Nearly a year after the concrete 3D printer was first unveiled, TU/e partnered up with Netherlands construction company BAM Infra to start a collaborative project – 3D printing a new concrete pedestrian and bike bridge. Now that bridge is officially open to cyclists.The 8-meter bridge was printed in parts, using 800 layers of reinforced, pre-stressed concrete, and has been safety-tested to ensure it can withstand loads of up to two tons.
Theo Salet, a professor of structural design at TU/e, told Dutch broadcaster NOS, “The bridge is not very big, but it’s all about rolling out a printer, which makes him unique.”
It was assembled in just six hours on site in the town of Gemert this week, connecting two roads over a water-filled ditch. It now forms part of a roundabout at the Handelseweg Boekelseweg (N605) and the Peeldijk (N272). The designers say it could withstand the weight of 40 trucks, though it will be used mainly by cyclists. At the official inauguration, hard hat-wearing officials took a celebratory ride over the bridge, which you can check out in a video by NOS.
One of the many advantages of 3D printing the bridge is a lot less waste, because TU/e’s printer only deposits the concrete where it’s needed, as opposed to the more traditional method of filling a mold. Lots of carbon dioxide is created during concrete production, so this is cut back as well.
“We connect for the future. We are constantly looking for a newer, smarter approach to addressing infrastructure issues and thus making a significant contribution to improving the mobility and sustainability of our society,” Marinus Schimmel, the managing director of BAM, said in a statement. “Innovation plays a crucial role here. 3D printing does not require any auxiliary materials, such as formwork. This produces significantly less waste and we need less scarce raw materials. This way of working also has a positive effect on the amount of CO2 emissions during the bridge production process.”
“Sustainability plays an increasingly important role in the construction and management of our roads. Therefore, we challenge market players to innovate, develop new sustainable technologies and reuse materials as much as possible,” said Deputy Christophe van der Maat. “When evaluating quotes and invitations to our projects, parties who come with an innovative and sustainable plan will also be our preferred. Even if that offer may be slightly more expensive than with the regular approach. The construction of the Gemert North is proof that the construction industry is also involved with both hands together with knowledge institutions.”
It’s also less expensive and faster to complete these types of projects using 3D printing, and there is more design freedom and customization.
“Thanks to the use of robots, each design can be realized in a unique way with the same effort,” explained Salet. “An important additional advantage is that all information gathered in the design process can now also be passed directly to the implementation. This is an important development in Building Information Management (BIM) as it brings closer links to the parties. Ultimately, the end user who benefits from this is in the form of higher quality and custom.”
Salet does want to reassure builders that just because robotic construction printers have arrived, they won’t be out of a job.
BAM Infra and TU/e have both said this is the first 3D printed concrete bridge in the world, and while that’s not entirely true, the new cyclist bridge was in fact designed using a special process, developed in a research group led by Salet, so each layer is reinforced with steel cables for maximum safety.
“The concrete is no longer needed by this method, but then people need to build and maintain the robots, so the work will change,” Salet said.
Both the university and BAM are now looking to the future – in addition to the cyclist bridge, TU/e has completed multiple tests with printed concrete, and hopes to move on to printing houses in Eindhoven, along with viaducts and larger bridges. BAM plans to have the 3D concrete printer at construction sites from now on, which would eliminate the necessity of having to drive 3D printed pieces to sites and assemble them there.
Discuss this and other 3D printing topics at 3DPrintBoard.com, or share your thoughts in the Facebook comments below.[Source: The Guardian]