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Advances in 3D concrete printing are aimed at remodelling construction into a robotic manufacturing process that is time, cost and carbon efficient – plus cool to kids seeking a career.
In reporting what could be a revolution in construction design and practice – the printing of concrete – it is perhaps best to start with an explanation of what printing in this context actually means.
Conventional methods of manufacture generally involve components being moulded into specific forms or cut from blocks.
In contrast, component printing – or additive manufacturing as it is more formally called – is based on liquids, powders, strands or film being layered to build 3D structures without use of a mould.
Printfrastructure
A leading proponent of concrete printing in the UK is innovation specialist ChangeMaker 3D which is pushing hard to move its Printfrastructure technology from concept development to reality. In this, it is being greatly helped by High Speed 2 (HS2) railway line builder HS2 Ltd.
“Printfrastructure involves using computer controlled robotic printers to extrude a rapid hardening cementitious mixture to produce concrete components,” says ChangeMaker 3D director Natalie Wadley.
“The layering process is very exact and materials economic. It can create lattice internals which add compressive strength and reduce weight. Printfrastructure also dispenses with carbon-heavy steel reinforcement in certain circumstances.
“Instead – subject to further testing – we aim to use microscopic strands of graphene which has shown early stage compressive benefits.
“We believe the removal of rebar, savings in materials and our robotic processes will help take concrete construction to whole new levels of safety and sustainability.”
Graphene is a product of flaked graphite, acclaimed of late as a wonder material. Wafer thin, it is said to be the strongest material ever tested.
We aim to use microscopic strands of graphene which has shown early stage compressive benefits
ChangeMaker 3D has a policy of working closely with industry specialists and this was the case with graphene.
Supporting the move away from steel reinforcement – and thereby greatly reducing the carbon count of Printfrastructure components – was Cheltenham-based advanced materials specialist Versarien, to which ChangeMaker 3D extends credit.
“It is apparent to us that a perfect confluence of graphene availability and development of printing capability has occurred,” says Wadley.
“It adds to our feeling that Printfrastructure’s time has come.”
Automation and digitalisation
She points to another major player in her company’s development of UK concrete printing capability. Dutch technology firm Cybe Construction is a specialist in construction industry automation and digitalisation.
Cybe’s focus is on developing and selling hardware such as 3D printers, fast setting sustainable materials plus software to simplify complex building processes.
The basic machines are manufactured by ABB Robotics, a Swiss-Swedish multinational. Cybe takes ABB products and modifies them, for instance digitalising front end controls and adapting nozzles to suit pumped concrete.
Printfrastructure technology can either be applied in a factory setting or in situ, on site, close to where it is needed. The printers weigh around 5t and currently have a robotic reach of 3m but work is underway to extend that by a further 1m or 1.5m.
A gantry can be installed to position the printer where the components to be printed are beyond 4m or 5m away from where the printer is sited.
I’ve been assured that what we are supplied with is 30% more eco-friendly than a conventional mixture
The material to be pumped arrives dry and in bags from Cybe. Wadley is limited in what she can say about what is, in effect, mortar.
“It’s difficult, in general, to engage in promotional activity when you can’t answer questions because of other people’s patents, or the fact that your own patents are pending,” she remarks.
“That’s one of the problems with progressing pioneering developments.”
She does say that after water is added to the Cybe material a “secret agent” comes into play, when the mortar is mixed correctly.
“I’ve been told there’s no ordinary Portland cement involved and assured that what we are supplied with is 30% more eco-friendly than a conventional mixture.”
Dries in three minutes
Typically, the Cybe mix dries in three minutes which is necessary for the process but means the nozzles must be watched to ensure they don’t clog up. Supply of materials from the Continent is not currently seen as a problem although there is an acceptance that demand may necessitate upscaling capacity, possibly in the UK.
Boosting ChangeMaker 3D’s industry credibility and its prospects for the future are its relationships with HS2 Ltd and its London tunnels contractor, the joint venture of Skanska Costain Strabag (SCS JV).
HS2 Ltd actively seeks small and medium size enterprises capable of developing new thinking, technology and processes. It has an innovation accelerator programme to encourage and facilitate beneficial change and a strategic aim of cutting the new railway’s carbon footprint.
HS2 Ltd innovation manager Rob Cairns says: “Innovation has a crucial role to play in cutting energy consumption and carbon emissions on HS2, so we’re looking for creative and fresh thinking on how to achieve this.”
High Speed 2 application
ChangeMaker 3D’s Printfrastructure fits well into HS2’s innovation mindset and the technology is to be employed on site in a major proof of concept trial by SCS JV in March next year.
“The structure to be built is a retaining wall to support spoil to enable us to launch tunnel boring machines in a sensitive area,” says SCS JV temporary works manager Andrew Duck. “Soil is being added to provide more surface cover to ensure safe tunnel boring machine working.”
Duck adds: “It’s important that we give such technologies [as Printfrastructure] the opportunity to flourish because of the possibilities it offers the industry to make a step change in how projects are delivered.”
Wadley acknowledges that such a change will have implications for UK design standards and codes of practice.
Already she is active in a working group compiling the international standard entitled “ISO/ASTM 52939 – additive manufacturing for construction – qualification principle – structural and infrastructure elements”.
Cairns believes that the kind of lean, clean, green construction that concrete printing and other new technologies will bring about will ultimately make the industry much more inclusive and attractive to young people seeking an exciting and interesting career.
“I think it will inspire the next generation,” he says.
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How are layers of concrete bonded with previous layers to form a homogeneous mass, and how is continuity of any necessary graphene or other reinforcement achieved?
From what I can gather, there is no tensile strength involved, the graphene is stated to add to compressive strength, which is fairly much beside the point. I think it’s just a fancy type of masonry.
Have to chuckle at the secret ingredient added to mortar to make it workable/printable. washing up liquid?
A manufacturing process? Back To The Future? Manufacturing is all about engineers, standardisation and quality controlled repetitive volume production. Is there nobody still around who remembers The Egan Report, entitled Rethinking Construction? Or better still prefab houses after WW2 which were considered a post war utilitarian necessity rather than an architectural art form to be featured in AJ? Ronan Point didn’t help although the lessons were leant, but as long as the built environment is controlled by architects promoting unique one off prototype developments and 200 year old arts and crafts, forward thinking engineers will come and go after a career of failing to change the system. Anyway, sprayed and pumped concrete were well established long before anyone thought or heard of product printing, but there was a man controlling the nozzle instead of a computer.
Incidentally the component pictured appears to be better suited to steel rather than concrete, and that is one step towards manufacturing.