Researchers develop a lego-like 3D printed alternative to reinforced concrete beams

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A team of researchers from Polytechnic University of Valencia (UPV) has developed a 3D printed alternative to reinforced concrete beams made from recycled plastic.

Although extremely strong, reinforced concrete beams are also very heavy because they contain a lot of metal. Therefore, moving such beams is often difficult and requires a large amount of energy.

To solve these problems, the researchers designed and patented 3D-printed plastic beams that can be assembled like Lego bricks and concreted in place, weighing up to 80% less than traditional reinforced concrete or metal beams.

“Our goal was to provide an alternative to the current reinforced concrete structures,” said José Ramón Albiol, professor at the Higher Technical School of Building Engineering (ETSIE) of the UPV. “These are made of profiles that build up the full length of the room, which requires expensive installations and is difficult to transport.”

The 3D printed plastic beam alternative to reinforced concrete. Photo via UPV.

3D printed beams inspired by human bones

The UPV team embarked on 3D printing plastic blocks that could be interlocked to form beams, as an alternative to traditional reinforced concrete or metal beams. In order to achieve significant weight savings compared to such beams, the researchers modeled their 3D printed blocks on the internal polymer profile structures of human bones.

The alveolar structure, typical of that found in the epiphysis – or terminal part – of bones, consists of a partly spongy layer with a trabecular porous framework and a thick and compact outer layer. The researchers reproduced this geometric structure in their 3D printed blocks to give them strength and rigidity while keeping the parts as light as possible.

The blocks were also printed using recycled plastics as raw material to improve the sustainability of the construction process.

“It’s a honeycomb structure, which makes it possible to reduce the plastic material used – and therefore its weight – while maintaining structural rigidity,” Albiol said. “And that’s what we’ve transferred to these revolutionary beams, especially the profiles. It is a very intelligent natural system and its replication in these beams gives them, together with a low structural weight, a very high mechanical capacity.

The 3D printed blocks are inspired by the geometry of human bones.  Photo via UPV.
The 3D printed blocks are inspired by the geometry of human bones. Photo via UPV.

A lego building block approach

The UPV team has been developing its 3D printed beams over the past three years and patented the system in October 2020.

Along with the weight-saving benefits of printing the plastic beam components, the main novelty of the researchers’ system is its modularity, whereby the 3D-printed blocks can be assembled on site to form a longitudinal beam. which is then fixed in place with a layer of concrete.

As a result, large trucks and cranes are not needed to transport and install the beams, saving time and labor and material costs.

“The system also eliminates the need for expensive formwork, allowing you to work without having to reduce traffic in the infrastructure in which you are working,” said José Luis Bonet of the University Institute of Concrete Sciences and Technologies (ICITECH). at UPV. . “Furthermore, this solution reduces the manpower and ancillary resources required, which translates into significant time and cost savings.”

Additionally, the use of 3D printing means that entire beams can be both fabricated and assembled on site, regardless of location, and beams can be customized to individual project needs, where required. .

“Being able to customize the beams in situ makes it possible to adapt the characteristics of each of them to the structural needs of each point of application”, added Miguel Sánchez of the Department of Informatics of Systems and Computers (DISCA) of the UPV. “The possibility of recycling polymer materials for the manufacture of the beams also reduces its carbon footprint significantly.”

The 3D printed blocks can be assembled like lego bricks and installed on site.  Photo via UPV.
The 3D printed blocks can be assembled like lego bricks and installed on site. Photo via UPV.

Advances in concrete 3D printing

The strengths of 3D printing have been increasingly exploited in recent years in the construction sector to provide improved material characteristics, reduce manufacturing times and costs, and reduce the sector’s carbon footprint.

In October last year, researchers from UC Berkeley has developed a new method of incorporating 3D printed polymer mesh into concrete structures as reinforcement. They were able to reduce the concrete content of the mix by approximately 33%, which made the overall weight of the structure much lighter while maintaining its load bearing capabilities.

Elsewhere, researchers from ETH Zürich used a combination of 3D printing and large-scale FDM molding methods to design an “eggshell” concrete 3D printing process. The method allows the team to produce complex concrete structures in a more material-efficient way.

More recently, scientists from Swinburne University of Technology and Hebei University of Technology embarked on improving sustainability within the industry by turning construction waste into 3D printable concrete.

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Featured image shows the 3D printed plastic beam alternative to reinforced concrete. Photo via UPV.

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