If robots can lay bricks, one of the oldest building materials used by humans, why can’t they also make bricks?
That was architect Christian Lange’s reaction 12 years ago when he saw a robot bricklayer developed by Swiss architects Fabio Gramazio and Matthias Kohler, founders of the first architectural robotic laboratory at ETH Zurich, the Swiss Federal Institute of Technology in Zurich, Switzerland.
And it was a thought that laid the groundwork for a robotics laboratory at the University of Hong Kong, where Lange is a senior lecturer in the school of architecture, and to a robot making 3D-printed bricks there.
The experimental facility, called the Fabrication and Material Technologies Lab, opened in October 2016. Because of the role ceramics have played in Chinese culture, Lange, who heads the university’s robotics team, specified that its first piece of equipment should be a 3D printer that could print clay.
“Ceramic bricks and tiles have been an important building material in Hong Kong and mainland China, but in today’s world, their role has been diminished to small surface detail on a concrete tower,” says Lange.
He set about reviving “this rich history” of Chinese brick making, but with a twist: the bricks his robots would make would have the potential to transform building design and construction.
Conventional bricks “are a great material system” that can be used to realise a vast array of architectural designs, Lange says. But they have their limitations.
A standard brick exists pretty much everywhere in the world, but to create elaborate terracotta structures, such as the Iron Pagoda in Kaifeng, a city in Henan province, central China, you need special bricks, he explains. The timber-framed pagoda, which dates from the 11th century, is one of the oldest and largest buildings constructed using glazed bricks and tiles.
“This new technology, being able to print your own material, offers to the architect a whole new world of how to express your building,” he says.
HKU’s technology consists of an industrial-scale 3D printer, a software program to design the bricks, and a robotic arm to control the manufacturing process.
Malleable clay is fed into the printer and, following a preset algorithm, bricks are extruded from the zigzag motion of the “ink” nozzle – just like a regular printer spits out documents from a work computer. They then need to be fired in a kiln.
Each brick takes three minutes to print, and is unique. Bricks can be tapered, curved, perforated or angulated, giving rise to endless architectural possibilities.
The first results of this pioneering process were revealed in a 3.8-metre-tall, Brutalist-inspired twisted tower, believed to be one of the first of its kind in the world.
Called the Ceramic Constellation Pavilion, a project led by Lange and fellow architects and HKU lecturers Donn Holohan and Holger Kehne, and with the participation of research assistants and architecture students, the installation was shown last year at Olympian City, a shopping and residential complex in Hong Kong’s West Kowloon region, with sponsorship from developer Sino Group.
It was mainly a proof of concept, Lange says. “With this one we had a few problems – we fired the bricks at too low a temperature [1,025 degrees Celsius (1,877 degrees Fahrenheit)] and actually the bricks were not strong enough.”
For their second project – undertaken late last year and exhibited as part of the recently ended 2017/18 Bi-City Biennale of Urbanism and Architecture (UABB) in Shenzhen, the Chinese city across the border from Hong Kong – the team fired the bricks at a much higher temperature (1,125 degrees), strong enough for use in construction, Lange says.
Another project, currently being worked on in the HKU lab, will explore the functional aspects of 3D- printed bricks. Project architect Holohan sees potential for the bricks to deliver an environmental benefit – something pertinent to Hong Kong, a city so “addicted to air conditioning”.
Holohan says the digital design and fabrication process allows for the construction of brick facades that can respond intelligently to environmental conditions. For example, bricks can be perforated to allow the movement of light and air through a building, or formed in such a way that water is channelled through or retained within the facade.
As the water seeps through the porous terracotta of the bricks and evaporates on their outer surface, it cools down the surrounding air – meaning such a brick facade could reduce the need to air-condition a building.
Bricks can also be designed to accommodate planters and green-wall systems, which can benefit dense urban environments.
“The technology allows us to create specific solutions to environmental and structural problems, as opposed to generic solutions – and, ultimately, to use less energy in the process,” says Holohan.
His work, both at the university, where he is an assistant lecturer, and in his multidisciplinary design studio Superposition, is focused on the socially and environmentally sustainable application of materials, technology and crafts.
At the HKU lab, the next experiment will be in 3D-printing concrete. The robotics team is in talks with Gammon Construction, a major Hong Kong-based construction and engineering company, about this research, slated to begin in June, Lange says.
Gammon Construction and Sino Group are far from being the only industry players interested in bringing new technologies to construction, he adds.
Ultimately, Lange and his team would like to see Hong Kong developers building using 3D-printed bricks.
He doesn’t expect them to replace concrete, though, conceding that building a high-rise tower from brick would not be economically viable. However, he sees exciting possibilities for incorporating new materials in building facades to “put the life back into architecture”.