“Digital Construction Platform” (DCP) may be considered an uninspiring name, but the swiveling robot arm mounted on a crawler truck has gained some considerable fame among architects and engineers. In July 2016, in just thirteen and a half hours, the robot raised the walls of a circular building in Mountain View, California. Only with the help of a printer nozzle stacking one layer of spray foam on top of another one. The result was a building with a diameter of almost 15 meters - the world's largest shell of a building printed in one piece. Once completed, Steven Keating was rightly happy. For six months, the engineer had screwed, soldered and programmed the control system of his apprentice robot. It was the crowning achievement of his doctoral studies at the Media Lab of the Massachusetts Institute of Technology (MIT) in Boston. There he worked in the research group of architect and designer Neri Oxman, who is known for the development of new materials and building technologies.
Engineers, scientists and architects around the world are working on new ways to build – with technologies such as 3D printers and unusual materials such as bacteria, silk or even living trees. Above all, however, they are in the process of rethinking architecture overall. Buildings should be recyclable, have a low carbon footprint, fit seamlessly into their built and natural environment and generally be perceived as an integral part of the world. "This holistic approach", says Oxman, "sees our environments - built, natural and biological - as one entity." This is one of the main reasons why the possibilities of 3D printing get so much attraction in the construction industry. The DCP-robot not only prints walls quickly, it also uses only as much material as is necessary – more at the bottom, less on the top. And commercial construction companies are already at it: Yingchuang Building Technologies in Shanghai, for example, in their facilities prints building parts made of concrete and debris, which are then assembled on site by workers to create complete houses. Concrete, probably the world's most important building materials, is also being further developed as a high-tech material. As we know it today, it is not without flaws. Frost and corrosion sometimes lead to premature deterioration after a few decades. Concrete also harms the climate. Its main ingredient, cement, accounts for roughly five percent of global carbon dioxide (CO2) emissions. Reason enough for materials researchers to try out new recipes.
Scientists in Aachen and Dresden developed "textile concrete" for the first time at the beginning of the 2000s. Instead of casting steel reinforcement in concrete, a special carbon fiber mesh is used, which is only a few millimeters thick but six times stronger than steel. A single-family house built with this "Carbon Concrete Composite", also known as C3, needed only walls a few centimeters thin. Façade slabs made of C3 are only two centimeters thick - instead of seven to eight as in reinforced concrete. This saves up to eighty percent of material, and because no rust-prone steel is used, it is much longer lasting. Pedestrian bridges have already been built with the new material.
Researchers are also developing self-healing concrete to extend its lifespan. Scientists at Delft University of Technology are experimenting with particularly robust bacteria, for example, which are able to wait in concrete for decades, even centuries. When water penetrates, they wake up - and begin to eat the food added to the concrete for them. As a by-product, they excrete lime into the cracks. This way, they can “heal” fractures of almost one centimeter in width.
However, sustainability can also mean reevaluating traditional building materials. For example, wooden skyscrapers are currently attracting worldwide attention, combining a lot of wood with a little bit of concrete. Currently, a 24-storey 84-metre high high-rise building in Vienna's Aspern district is being built from this mix of materials. Once completed - planned for 2018 - it will be the tallest building of its kind in the world. A reinforced concrete core holds the structure in place, but 75 percent of the material used is wood, whose production sends hardly any greenhouse gases into the sky.
Following the idea of natural wood as building material, one ends up with the "Fab Tree Hab", conceived in 2008 by the New York architect Mitchell Joachim. His plan is to have trees grow over a computer designed plywood structure in order to form, over time, a real living home. If the windows were made of glass they would break though due to the window frames naturally growing; therefore Joachim suggested having them developed based on soy. The plan has not yet been realized to this day, but living plant engineers such as the architect Ferdinand Ludwig from Stuttgart are working hard to create buildings with the help of growing plants. Ludwig, for example, had a whole tower of silver willows sprout around a steel skeleton north of Lake Constance.
In general, works by architects are increasingly inspired by nature - for example, by silk cocoons. In 2017, experts from the University of Stuttgart spun glass and carbon fibers around a scaffold with industrial robots and a drone to form a pavilion. Of course, one can also leave such a task to nature directly. Neri Oxman and her students dropped 6,500 silkworms onto a dome-shaped aluminum frame where they wove a dense net. However, this did not result exactly in a wind- and weather-proof structure. Oxman's most recent project, on the other hand, aims to integrate buildings into their environment in a sustainable manner. At the Milan Fashion Week in spring 2017, the designer presented a glass printer weighing a ton that allows glass objects to be produced in varying thicknesses, structures and colors. Her team not only wants to create new transparent building blocks, but also explores how they can generate solar energy or help regulate the heat balance of a building. “In the USA alone, around 42 billion square meters of window glass were installed in 2015", says Oxman. "Glass with additional properties could help us combat the effects of climate change."
Text: Hubertus Breuer
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