Reinforcing concrete with 3D printed polymer lattices

Concrete is one of the most widely used man-made building materials and one of the world’s most consumed substances, second only to water. It is cheap, abundant, and capable of heavy loads, but, it is also brittle and tends to crack. Therefore, concrete needs to be reinforced. Recently, researchers at UC Berkeley have developed a novel way to reinforce concrete with 3D printed polymer lattice structures – a way that improves concrete’s ductility while reducing the material’s carbon emissions.

In fact, engineers have been reinforcing concrete with polymer fibers for six decades, so the concept isn’t new in itself. However, the technique was different: fibers were typically mixed into concrete before it was poured, which meant the fibers were not distributed evenly. As a result, one part of a structure would have a high concentration of fibers, while another had almost none, leaving a path for cracks to form. Enter 3D printing. The benefit of a 3D printed lattice reinforcement is that a series of trusses stops cracks before they grow too large.

All image credits: UC Berkeley

Previous lattice reinforcements were two-dimensional and had a limited capability to support complex concrete designs. So the researchers wanted to manufacture a 3D design that could support heavy loads from all directions. For that purpose they used the octet truss for the lattice structure. Popularized by the architect Buckminster Fuller in the 1950s, the octet truss is known for being strong but also light at the same time.