A panel, shelf, and pedestal with free-form voids were all created by Enrico Dini using 3-D printing. Courtesy of Enrico Dini
Early efforts with 3-D printing show great promise, but work remains to adapt the techniques to large-scale construction projects.
August 14, 2012—Like many Europeans, civil engineer Enrico Dini dreams of the day when he can finally build that special villa. Where Dini’s dream differs is that he hopes to print his villa, and not necessarily for himself.
“Definitely if I had a budget of a few million [Euros], I might print a villa,” Dini says. “But I have never been so lucky to find a multimillionaire to say ‘OK, Sir Dini, this is a budget of let’s say, 5 million. You are a black box. Do what you want to do. And deliver to me a free-form, 3-D printed villa.’ Under this scenario, I could already achieve that goal for sure.”
Dini is chairman of the London-based Monolite UK Limited, a company developing a method of additive manufacturing, also known as 3-D printing, with future implications for the engineering and construction industry. In essence 3-D printing is a means of producing three-dimensional solid objects from digital models. Dini is a pioneer in 3-D printing. He has created intricate, graceful sculptures and artificial coral reefs with his massive 3-D printer.
The eventual promise of 3-D printing for construction lies in the creation of high-strength, reinforced concrete in free form shapes that are currently impossible to create with even the most inventive form work. Such an advance would enable architects and engineers to realize complex structures with sweeping, double curvature surfaces.
“There is an increasing desire for complicated buildings,” says Richard Buswell, Ph.D., a professor of civil engineering at Loughborough University, in Leicestershire, United Kingdom. “I know there are architects and engineers we work with who are bombarded with calls for things that can’t be made or manufactured.”
A massive machine distributes a chlorine-based liquid, mixed in
seawater, onto the areas to be printed, creating a cross-linking
reaction with oxides mixed into sand. Courtesy of Enrico Dini
To realize the promise of 3-D printing, such researchers as Dini, Buswell, and others must work through the details of a complex process in its infancy.
Dini begins with fine sand mixed with a metallic oxide reactant. His printer lays down a thin layer of this sand in a sheet. Next, multiple nozzles precisely direct a chlorine-based liquid, mixed in seawater, onto the areas to be printed, creating a cross-linking reaction that transforms the sand into something akin to sandstone or limestone. The process is repeated until the image is formed.
“The process is in the very early stages,” Dini says. “We have to manipulate a lot of sand back and forward. It takes a lot of sand to make the substrate. And finally you have to take [it out] at the end of the process. So it’s quite laborious. And we do it not by hand, but almost by hand. We move a lot of sand; we are completely covered with dust all over.”
The inherent advantage of Dini’s method is that any sand not involved in the reaction is in place to support overhangs of material for the layers above.
Buswell and his colleagues at Loughborough University use a repurposed gantry crane to shuttle a deposition head with a three-axis movement to place mortar, creating the printed object. The mortar employs a chemical curing process and hardens to a material akin to high-strength concrete.
“Part of the art of getting the process to work is working within the confines of the material and making sure you get good bonding in between layers,” Buswell says. “We have been doing a lot of work to make sure that happens and to also make sure we get a very solid, dense product.”
Richard Buswell, Ph.D., and a team at Loughborough University
used 3-D printing to create a double-curved panel. Courtesy of
Buswell has developed a proprietary method to support material overhangs on upper levels. His team is in the process of commissioning a robotic arm that will enable printing of three-dimensional layers, following the contour of an object, rather than creating it from flat layers.
Researchers in the field are excited by the potential applications of 3-D printing for construction, but acknowledge that although the concepts have been proven through early work, the techniques are still to be perfected.
“I have to swap many hats on my head,” Dini says. “The first hat I have to put on is the hat of the machinery developer and builder. There is the first challenge—developing an industrial printer. Our printer is actually an artisanal printer. The main challenge is being able to manipulate a large amount of granular material back and forth. This needs a filling system, properly done—a reliable machine, a fast machine.”
Developing the perfect material for this technology is another of the challenges that remain. Buswell said his team chose mortar because the construction industry is familiar with it, and his colleague, Simon Austin, Ph.D., CEng, a professor of structural engineering and associate dean for teaching at Loughborough, has decades of experience in concrete material science.
“We were keen to explore the possibilities of this sort of additive approach for construction manufacture,” Buswell says. “We felt that to do that with a material that is maybe a little alien to the construction industry, [it] would be very challenging to engage them. So we felt that if we used a material that is very well understood, we would have a better starting point to convince people.”
That strategy seems to have worked. Buswell’s team has drawn support from the Engineering and Physical Sciences Research Council; the Bath, United Kingdom-based engineering firm Buro Happold; and the London-based architecture Foster & Partners.
“There are a lot of materials out there, a lot of composite possibilities,” Buswell says. “And we’re yet to explore them. We thought it was a good starting point. But I think it is just a starting point.”
Where is 3-D printing likely to appear first within an industry that is understandably conservative and frugal? Dini expects the first adoption of the technology will be to create large, free form blocks that will utilize an exterior application of concrete for a smooth surface and added reinforcement. Another possibility is 3-D shells that are then filled with conventional concrete.
Enrico Dini is a pioneer in 3-D printing, creating intricate, graceful
sculptures with his innovative process. Courtesy of Enrico Dini
“So what I see is a hybridized building technique, to be an honest engineer, as I am,” Dini says. “On one side I am a dreamer and on one side I stay firmly on the ground.”
Buswell agrees that 3-D printing will face a challenge to being accepted. “With any new technology, getting it from proving the concept works to covering a building with it is a huge step. The construction industry is a cost-based industry, and it is conservative. We don’t want bits of buildings falling on people. So I think [this is] actually quite challenging to overcome.”
He sees an early adaptation of the technology in the creation of panels curved in two directions, which will free architects and engineers from the current constraints of precast panels.
“So that is clearly going to come at a cost premium at first, which is why we are sort of heading to the high-end market,” Buswell says. “With any technology, it will start with someone willing to pay for it. And [the cost] will come down. I don’t see any reason why it won’t follow those sorts of patterns.”
An additional benefit of 3-D printing that could help speed its integration into the industry is the ability to optimize building components, reducing materials while maintaining strength.
“You can technically print with less material, because you can design out material you don’t need,” Buswell says. “With a cast process you are always restricted to filling [it] up. That’s the big take home. If you’ve got a three-dimensional model in a computer, then why not apply some optimization to it? Take away the stuff you don’t need.
“I think more than just saving material, particularly with concrete and other materials, you are saving carbon dioxide,” Buswell adds. “You are removing that bonded-in carbon and the energy it takes to produce the material.”
Dini sees great potential for the technology in such maritime projects as coral reefs and coastal refurbishment. He hopes to develop his 3-D printing method with open-source techniques that challenge innovators to develop the best machines, materials, and techniques.
“We need a quantum of energy in terms of logistics and human resources to make it happen,” Dini says. “I am spending all my life on it. Day by day this community is growing. I’m honored on one hand, on the other hand it is time consuming and life consuming.”