The latest experimentation with digital fabrication and alternative materials in 3D printing involves decomposing glass, sawdust, concrete, and even stone into baser forms such as powders and liquids. This diversifies the repertoire of materials that can be fed into a 3D printer. “The advantage of the powder-based process is that it accommodates a number of materials, any material that we can grind into powder,” said Ronald Rael, associate professor of architecture at UC Berkeley. The environmental and economic implications of cost cutting, automation, and recycling in design, construction, and manufacturing are game-changing. Rael’s recent project, Bloom, is a 3D printed, powdered concrete–based pavilion recently debuted by UC Berkeley’s College of Environmental Design. The undulating, mesh-like structure consists of 16 concrete panels, each one light enough to be lifted into place by two people, rather than a crane. Rael mixed polymers with cement and fibers to produce resilient, lightweight, yet “high-resolution” concrete skeletons. “The extrusion-based processes involve pumping wet cement through a nozzle and you can only stack wet cement so high,” said Rael of traditional 3D printing. “But with a powder-based process, we could make [lightweight] blocks and send them to the moon.” Composed of 804 custom-patterned bricks, the mesh-like configuration increases load-bearing capacity while decreasing surface area.
Berlin-based firm ZA Architects used a similar digital fabrication approach to revive 19th-century stone masonry techniques, deploying a robotic arm to expedite construction. Inspired by Catalan vaulting, in which bricks were substituted with thin tiles and traditional mortar with rapidly hardening cement, this self-supporting technique nullified wood scaffolding while allowing builders to create vaulted ceilings 3-to-5 times wider than traditional timber arching. Coining the term “foam casting,” ZA’s approach uses the same tessellated composition but with stereotomic blocks made of rubber foam saturated with pure Portland cement, each one a unique shape. “The robotic arm can operate only with units of certain size and weight,” explained Arina Ageeva of ZA Architects in an email. “To lay them one-by-one is possible only on vault-like geometries. That is why all horizontal surfaces are vaulted thin shells that are seamlessly integrated into the walls.” The robotic arm assembles the tiles floor-by-floor into a seamless, self-supporting mesh that can replace walls, columns, and beams. Assembly time is also much faster than a 3D printer.
California-based firm Carbon3D has developed a 3D printing technology that is 25-100 times faster by “growing” objects from a pool of liquid resin, resulting in uniform mechanical properties which layer-by-layer 3D printing lacks. The firm’s Continuous Liquid Interface Production (CLIP) technology controls the balance of UV light, which triggers photopolymerization, and oxygen, which inhibits the reaction. The object’s shape is formed by an oxygen-rich “dead zone” in which photopolymerization cannot occur, and is created by a special permeable window similar to a contact lens that controls the flux of oxygen. “This continual process is fundamentally different from traditional bottom-up printers where UV exposure, resin renewal, and part movement must be conducted in separate and discrete steps,” explained Carbon3D co-founder and CEO, Joseph DeSimone.
Three-dimensional printing with liquid polymers yields materials with versatile mechanical properties that can be exploited in a range of industries. “In essence, we are able to throw the entire polymer chemistry textbook at this and make parts that range from hard prototyping resins, to great elastomers that range from materials with high elasticity for athletic shoes or high dampening for applications like engine motor mounts for vibrational control […] and even completely biodegradable materials,” DeSimone explained.
Believe it or not, the T-1000 robot in a Terminator 2 clip, which is made of liquidmetal, inspired the technology. “The co-founders thought, ‘we should be able to grow something as continuously as T-1000, we shouldn’t have to rely on the slow 2D layering over and over again,’” said DeSimone. “We brought a new perspective to traditional 3D printing, bringing our expertise in chemistry and physics to an industry that relied on mechanical processes.”