Concrete doesn’t seem like a material that is ripe for 3D printing – but Skanska is partnering with a range of firms to conduct research into this technology at a facility in the Midlands, with some success.
There has been a great deal of discussion about the potential applications for 3D printing in construction, but little in the way of practical examples so far.
Any companies that have experimented in this area have generally worked on a small scale, with larger-scale 3D printing of components (or even whole buildings) still some way off.
Skanska, however, has dived into working with the technology, experimenting with 3D-printed materials on a range of projects in recent years. The firm is now working with a number of partners, including Foster + Partners, Tarmac, robotics company ABB and Loughborough University, to carry out research into the 3D printing of concrete – and is having some success.
The research is taking place at the Manufacturing Technology Centre on the outskirts of Coventry. A fairly unassuming cluster of buildings on a business park, separated by a man-made lake, inside is a hub of research into high-value manufacturing.
Names of innovative companies and captains of industry adorn the walls and meeting rooms, and as Construction News is taken upstairs we pass a balcony that overlooks the workshop floor, which is covered in machines of all shapes and sizes that form part of the research being undertaken.
The 3D concrete printing research, though, is taking place in an adjacent building, in a secure facility protected by security swipe cards to ensure that only authorised eyes are able to see what is going on – indicative of the potential value that Skanska and the project’s other partners believe it has.
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Skanska first started exploring the potential of 3D-printed concrete two-and-a-half years ago, explains innovation manager David Lewis.
“We decided to concentrate on printing very difficult precast components. We’re not looking at whole buildings”
David Lewis, Skanska
Loughborough University, one of the research partners, began its research as long ago as 2007, with Skanska coming on board to help accelerate the process and work out how it could be applied in the field. Tarmac is providing all of the material for the concrete mixes, while Foster + Partners is working on the component designs. ABB is providing the equipment.
“We decided to concentrate on printing very difficult precast components, with overlays and voids that you can’t really make using precast, using MTC to help us industrialise the process,” he says. “We’re not looking at whole buildings here.”
The team is using a six-axis robotic arm to print the concrete, giving it the flexibility to place the concrete in the positions required to layer up components.
The system is demonstrated for us, although no photography was allowed. The arm lays thin strips of concrete in a continuous pour to form the bottom layer of the component – before then placing another layer on top. This is certainly additive manufacturing, but it does look slightly different to the traditional concept of 3D printing that you may have seen before, with components effectively made by a thin nozzle pouring controlled layers of concrete on top of each other.
Interestingly, the team says that getting the robotics technology right was relatively straightforward – but that getting consistency with the concrete mix has been far more problematic.
Manufacturing Technology Centre
The mix has to be relatively stiff when compared with normal concrete: strong enough not to slump before another layer is placed on top by the robotic arm, while also remaining soft enough that the new layer bonds with it before it cures.
“It comes out [of the nozzle] at around 10 kN of strength,” Mr Lewis explains. “The thickness can be set to 9, 10, 15 or 20 mm at the moment. The reliability of the mix is definitely the biggest challenge.”
The team has an array of differently shaped components that have already been printed, and Mr Lewis says clients are already expressing enthusiasm in the potential benefits this approach could bring.
“Highways England is interested in what we’re doing,” he says. “We could use this method to make components lighter, which would reduce CO2 emissions and also increase certainty and reduce waste.”
“The reliability of the mix is definitely the biggest challenge”
David Lewis, Skanska
The team is still experimenting with what shapes can be printed, and is even exploring the possibility of printing rebar into the components. Most of the prototypes so far are for cladding, rather than structural elements.
Skanska director of innovation Sam Stacey is excited about the prospect of increasing production, with the team receiving a grant from Innovate UK to help support the industrialisation of the process.
“I didn’t expect [industrialisation] to be as complicated as it is,” he says. “The upside of that, though, is that it will be harder for our competitors to copy this – it is quite difficult to make this work [at scale].”
More broadly, Skanska has become a paying partner at the MTC, and is leveraging its resources to help speed up innovation within the business, with the 3D concrete printing project just one of many potential initiatives.
“Looking beyond construction is really important,” says executive vice president Thomas Faulkner, who is also on site to show us the 3D printing in action.
“We can’t be insular and think the improvements we’re starting to see will transform us. The aerospace and automotive industries were equally competitive environments 10-15 years ago, but they came to the recognition that, if they wanted to deliver better value for customers, they needed to be more collaborative,” he adds.
Kieran Taylor of MTC, Nich Gazard of ABB and David Lewis from Skanska
The MTC is providing an environment to share ideas across industries, with its pool of engineers working across multiple projects in multiple sectors at any one time, and partners encouraged to work hand in glove to get the most out of their membership (see box).
For example, Skanska’s Mr Lewis spends two or three days a week at the MTC, helping to shepherd projects like the 3D concrete printing along, as well as spending time in the company’s own offices and on sites.
The whole team is clearly proud of how far the 3D concrete printing initiative has come – and it’s not hard to imagine the components it is making in widespread use in the very near future.
“[Being involved with MTC] is about accelerating our learning,” Mr Faulkner says. “We’re trying to solve some of the challenges that we have with different thinking and different skills.
“The construction industry, historically, has invested less than 1 per cent of revenues into R&D, and we need to create a platform where people are investing more.”
Through centres like the MTC and projects like the 3D concrete printing initiative, that innovation will increasingly come to the fore.
A special place
“This is quite a special place,” says the MTC’s head of group business development Steve Statham.
The Manufacturing Technology Centre first opened in August 2011 after receiving a £40m government grant. It is one of seven facilities dotted around the UK that are together known as the high-value manufacturing catapult.
The MTC specialises in manufacturing technologies and processes that are particularly important to the high-value manufacturing sector – other centres specialise in areas as diverse as composites, nuclear, advanced machining or process innovation.
Mr Statham explains that, early on, the aerospace and automotive industries were quick to embrace the catapult – with construction joining the party more recently.
“We sat down as an exec team and worked out which sectors we wanted to align ourselves with beyond [aerospace and automotive], and with construction being such a major part of the UK economy it fell into that category of sectors to explore,” he says.
“The initial hook was the government challenge about building a million houses by 2020 – we thought that was something for us to go at. Then we tripped over the fantastic Construction 2025 document, and the floodgates opened.”
The MTC now has four areas of focus when it comes to construction: residential and commercial building, which is where the 3D concrete printing falls; infrastructure; utilities; and the supply chain.