Behrokh Khoshnevis is an engineering professor at the University of Southern California and the inventor of Contour Crafting technology, an automated fabrication process that can rapidly prototype large-scale components in layers. Think robotic arms and extrusion nozzles that can 3D print entire buildings with cast-in-place concrete.
In your TED Talk on Contour Crafting, you say that the ideal material would be a cementitious mix with a 10,000-psi strength.
That’s one choice. We can use an array of cementitious materials, with different proportions of concrete, or polymers.
What about the installation of reinforcing steel?
[Concrete construction can use] different methods of reinforcement, such as composite fiber mixed into concrete. In certain rebar [designs], assembling rebar segments while it’s been constructed—steel rebar or steel cores—all of this possible.
And this technology can build a 2,500-square-foot house in about 20 hours?
What impact will this have on architecture?
This technology belongs in the CAD, CAM, and CIM [realms]—like 3D printing. You design something, and you just let the machine print it for you. As I understand it, architects have many intricate geometrical designs they aren’t building because they’re expensive to manage. With Contour Crafting, that will not be a concern.
What type of equipment is required?
You can have multiple printers on the site for building large buildings, or one joist printer and multiple nozzles, or just one small printer and keep moving it from location to location.
How much will the equipment cost?
Like a typical concrete pumping truck, which is about $600,000. My estimate for an early-entry Contour Crafting machines is about half a million.
What is the status of your work with NASA to develop Contour Crafting technology for building lunar and Martian structures before human beings land?
We’re making lot of progress with the project. We have tested some approaches with a smaller machine. Now we are building a bigger robotics system to build a much larger structure. We are advancing our innovations. We are building landing pads, interlocking tiles, and blast-protection walls to protect the settlement from projectiles that the landers throw upon landing and takeoff. We are working on roads, hangars, landers, other equipment walls, and shield walls for radiation. We are not working on habitats or on pressurized structures at this point—that would be the next phase.
How far away is this technology from mainstream use here on Earth?
Early entry for small, low-income housing and emergency shelters could be as early as two years away from commercialization. It all depends on the funding situation.
What feedback have you received from code officials, architects, and engineers?
I have received numerous feedback. Architects around the world are pretty excited about this. They’re my strongest advocate. I haven’t had many people in the regulatory part of buildings contacting me, but there have been a few. This means it’s all building code standard development, of course; also the process of inspection has to be changed for this technology. It doesn’t make sense to build in one day, but have to wait a couple weeks for city inspection to show up in a couple stages. The inspection process has to be very redeveloped for this; we need to have simultaneous inspection. We’re actually working on something [to resolve this].
It is less stringent in developing countries, but nonetheless, we obviously have to do a good job and make sure that the buildings will be safe. Just for human’s sake, we have to do that. Also if the technology is put together in a sloppy way, used somewhere, and then some catastrophic thing happens, that would be a big blow to the technology.
What is Contour Crafting's potential social impact?
It’s good because it’s automatic. [In the case of] slums, it can improve the quality of housing and elevate standards of living. When people have their basic needs met, according to Maslow’s [Hierarchy of Needs], they elevate their levels of human aspiration. They go after education, they become intellectuals contributing to the society. The population size will decrease because everywhere you have slum housing, you have a high density of population. The impact will be huge, I think. It will bring up the craft of people on earth.