Affordable 3D Printed Structures
3D Model makers are now “printing” houses and bridges, with an eye towards (someday) structures on the moon
This article will start out talking about 3D Printed Housing, a method in which giant two-axis “printers” spew out construction material (usually a type of concrete), so as to build an inexpensive building. This is done in the same way that a 3d model maker makes a plastic item, by receiving instructions from a computer that contains a 3d object of some sort (often using some kind of Autodesk software) and building that object layer by layer until the 3d object is complete. Since concrete is a compressive strength material, and buildings sometimes need tensile strength materials (often steel or timber), 3d houses are currently limited to compressive-type building elements, such as walls. Not to worry though, the Romans effectively used the arch shape so that they NEVER needed tensile strength materials! The prospects for 3d housing, currently envisioned for low-cost single family housing, might someday be utilized to build gigantic multi-family apartments, also at low cost, or even structures on the moon or mars (using native materials). Here is an explanation of the technology, it’s possibilities, and of the prospects for solving the housing problem.
There are several companies leading the way in 3D building technology. The D Shape Company uses a magnesium chloride binding liquid mixed with sand to lay out 5 to 10 mm layers of a sandstone-like material. The resulting structure has more tensile strength than concrete, and is lighter so it can take on a variety of shapes at relatively low cost. The European Space Agency (ESA) has contracted D Shape to use it’s machinery for building structures on the moon, since it’s technology could theoretically use native “moon dust” materials, reducing space craft payloads. D Shape has also built one of the few 3D printed bridges, having a length of 12 meters and a width of 1.75 meters. This is significant as concrete bridges are complex, expensive and time consuming to build, begging for cheaper, simpler alternatives. (dshape.com, n.d.)
Another major player in the 3D building business is the makers of FreeFab Wax, a kind of 3D printed wax mold material that can be used to shape precast or glass fiber reinforced concrete materials which are sprayed over the mold. After the wax mold is used, it can then be melted down and reused for another application. This technology is again faster and cheaper than conventional molds or forms. XTreeE and SQ4D are other major players in the 3D building market. COBOD International is becoming a major 3D home making company in Europe. (freefab.com, n.d.)
Look for 3D building to become the mainstay of bridge and large building structures in the future, once the best blends of materials and shapes are decided upon. For bridge building, lighter weight concrete materials may be sprayed over steel post-tensioning cables, without all the time consuming falsework and forms necessary in conventional bridge building (which essentially requires building the bridge twice, once with wood forms and again with the concrete). Building construction may evolve to a point where a cement can be used with native materials (“dirt” or sand from the site to be built upon) which would greatly reduce building cost. Since sand and soil typically have some strength with a proper binder (like epoxy or cement), they could be used as part of a structural material. This would be along the lines of a brick building (clay bricks bound together with cement mortar). Once again, lack of tensile strength would be a challenge, and arched or domed shapes might be used to get around this, or perhaps round “conduits” could be cast in the shape to contain steel tendons, used to provide tensile strength. Additionally, hollow chambers could be cast for insulation (dead air space is an excellent insulator), while plumbing chases and electrical conduit spaces could also be cast.
It is not hard to envision this technology being used to build large apartment buildings, although probably not in the tall skyscraper sense (this may remain the domain of steel, which is far stronger than anything currently being cast by 3D printers). 3D apartments may find a place as 3 to 4 story buildings in places where there is more land available. Light tubes and “hamster tube” transit conveyances could be cast into the 3D shapes, so that apartments were sunny, and transportation from apartment directly to major transit terminals was possible. Swimming pools, gyms, and dining areas could also be directly cast into the 3D shape.
Meanwhile, in Manhattan, space limitations may preclude wide use of 3D for tall superstructures, but not for superstructure interiors, which may be 3D printed to form interior walls and floors. Someday, perhaps even transparent materials will be printed to form windows, or even molten steel alloys will be 3D printed. Car bodies are already being 3D printed (although this is still relatively expensive). In the tradition of Clyde Crashcup, we are close to “if you can draw it you can build it”. On land, in the ocean, or on the moon, 3D may make any shape possible. It’s time to get ready for the 3D future.
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