Lightened load: Two concrete casts illustrate how porosity can be changed in a structure. The cylinder, which mimics the cross section of a palm tree, is dense on the outside and porous in the middle. The samples were created with help from the Building Technology Program at MIT, directed by John Fernández.
The pattern could also account for the need to allow light into a building. Some areas would have strong, dense concrete, but in areas of low stress, the concrete could be extremely porous and light, serving only as a barrier to the elements while saving material and reducing the weight of the structure. In these non-load-bearing areas, it could also be possible to print concrete that’s so porous that light can penetrate, or to mix the concrete gradually with transparent materials. Such designs could save energy by increasing the amount of daylight inside a building and reducing the need for artificial lighting. Eventually, it may be possible to print efficient insulation and ventilation at the same time. The structure can be complex, since it costs no more to print elaborate patterns than simple ones.
Other researchers are developing technology to print walls and other large structures. Behrokh Khoshnevis, a professor of industrial and systems engineering and civil and environmental engineering at the University of Southern California, has built a system that can deposit concrete walls without the need for forms to contain the concrete. Oxman’s work would take this another step, adding the ability to vary the properties of the concrete and, eventually, work with multiple materials.
Oxman’s approach will probably be applied on a relatively small scale at first, in consumer products and medical devices. She’s used her principles to design and print wrist braces for carpal tunnel syndrome, customized for each patient. The approach could also improve the performance of prosthetics.
Oxman is developing her techniques in partnership with a range of specialists, such as Craig Carter, a professor of materials science at MIT. While he says her approach faces challenges in controlling the properties of materials, he’s impressed with her ideas: “There’s no doubt that the results are strikingly beautiful.”