PLAN 80: Article
Expanding The Potential Of Building With Concrete

3D Printing Opens Up New Possibilities

Researchers at the Media Lab are developing a system for the 3D printing of concrete with the ultimate potential of actually 'printing' an entire building.

Pursued by assistant professor Neri Oxman (PhD'10) and master's candidate Steven Keating, the process could make it possible to create fanciful concrete shapes that would be difficult or impossible to mold using traditional wooden forms. It could also allow the properties of the concrete to vary continuously, producing structures that are both lighter and stronger than conventional concrete by mimicking structures found in nature.

A palm tree, for instance. The trunk of a palm tree is denser at the outside and lighter toward the center, resulting in a high strength-to-weight ratio, as opposed to a man-made concrete column in which the density is constant throughout, producing a much heavier structure. As part of his thesis research – and in collaboration with Timothy Cooke and John Fernandez from SA+P's Building Technology group – Keating has already created sections of concrete with the same kind of density variations found in palm tree trunks and in bones, which consist of a hard, dense outer shell and an interior of spongy material.

The 3D printing technology – or '3DP', as it’s called – involves building up a shape one thin layer at a time, using a metal platform mounted on a piston that’s raised or lowered in tiny increments. A layer of powder is spread on the platform, then a print head deposits a liquid onto the powder to bind it together. The platform is then lowered infinitesimally and another thin layer of powder is applied on top of the last, followed by another layer of binder. Different combinations of powders and binders can make a range of materials or even a mix of different materials in the same printed object, using different liquids in the print heads, like the different colors of ink in an inkjet printer.

The technology of 3DP was pioneered at MIT nearly two decades ago, initially for the purpose of producing architectural models and prototypes for new products such as medical devices, but it has since branched out in a range of directions. Oxman has produced a glove with sections that are stiff and others that are flexible, designed to help prevent the wearer from developing carpal tunnel syndrome. She has also designed a chair made of different polymers, producing stiff areas for support and flexible areas for comfort, all printed out as a single unit.

A project at the Media Lab is developing machines to print food ranging from candies to complete meals. And one former student, Peter Schmitt (PhD’11, Media Arts and Sciences), working with Media Lab IP consultant Bob Swartz, has printed entire working clocks with all their gears, chains, faces and hands in a single unit.

The 3D printing of concrete is an initiative of Oxman's Mediated Matter Group at the Media Lab, exploring how digital design and fabrication technologies can transform the design and construction of objects, buildings and systems. To see a video, go here.

This story is based on a piece that was researched and written by David L. Chandler, MIT News Office.