Composite building materials redefine modernism at Exhibit Columbus

At Exhibit Columbus—an annual event honoring modernism in architecture—two research fellows are upending form and function using composite building materials.

Image courtesy of Christopher Battaglia

composite building materials rendering of Filament Tower

Zach Mortice

July 2, 2019

min read

Since the advent of modernism, architects have dreamed of the perfect material to unify structure and surface. Steel beams and glass windows were the 20th century’s solution, combining the elements holding up buildings and the elements covering buildings into one tidy duo. This century, academic researchers are throwing out this dichotomy as they seek one ideal material to create the container and the contained.

Two researchers are making great strides in this arena. Marshall Prado, an architecture professor at the University of Tennessee, is experimenting with composite building materials—specifically, an ultrastrong fiber system made from carbon and glass fiber. And Christopher Battaglia, a Design Innovation Fellow at Ball State University, is developing 3D printed, concrete-molded panels that hold similar potential for new material fabrication.

Both materials have the heft to hold things up and the dynamic articulation to create new forms. And both academics are inaugural University Design Research Fellows at Exhibit Columbus—an annual exhibition held in Columbus, Indiana, honoring the small city’s world-class collection of mid-century modern architecture.

In August, Prado and Battaglia will unveil pavilions showcasing their research alongside installations paying homage to architecture built by J. Irwin Miller and Xenia Miller. During Irwin’s tenure as the head of Cummins, a 100-year-old diesel-engine manufacturer, the company sponsored the era’s best architects (Eliel and Eero Saarinen, I. M. Pei, Harry Weese) to design myriad public and private buildings. “Columbus and the modern movement have always been about the advancement of technology and materials,” says Anne Surak, director of exhibitions at Exhibit Columbus.

Carbon strength + glass transparency

Shaping carbon filaments (video: 0:04)

Prado’s installation, Filament Tower, is a 30-foot structure made from carbon-and-glass fiber known for its high strength-to-weight ratio. To construct the tower’s components, a reconfigurable steel frame is rotated on a two-axis turntable, like a rotisserie, while a robotic arm winds carbon and glass fiber strands that have been impregnated with epoxy resin back and forth across the structure. The resin cures and becomes rigid, and the piece is placed in a tempering oven, making it even stronger. After the structure cools, the steel form is removed. The resulting composite strength works in tension but also in compression. Vertical sections of the tower’s 27 pieces screw together easily. “What’s left is just the composite material,” Prado says. “It’s the whole structure.”

The 30-foot tower is a riff on the iconic spires that adorn Columbus’s modernist churches, like those on Eero Saarinen’s North Christian Church. Filament Tower echoes the church’s hexagonal design, but the result is not sharp, mathematical geometry—Filament Tower is sinuous and organic. An example of biomimicry, the structure recalls the tightly wound fibers in the protein matrices that shape many organic structures. For example, trees and plants are made from cellulose fibers, collagen fiber is a common biological connective tissue, and insect carapaces are made from chitin fiber.

In addition to these evocative elements, perhaps the composite material’s most astounding feat is its transparency. “It really challenges what you think of as a structure because these materials like glass fiber are translucent,” says Prado, who used Autodesk PowerMill to fabricate the tower.

In architecture, typically “you have one system for your structure, you have one system for your enclosure, you have one system for HVAC,” Prado says. “Usually in biology, everything is functionally integrated. Your structure is your enclosure. It’s your thermal regulation system—everything.”

A century of carbon

Because the material used for Filament Tower is strong, light weight, and transparent, it could work equally well in structural or facade applications. Its modular nature also suits it to mobile and rapidly deployable infrastructure needs. Long-span structures such as bridges could be woven together like fabric.

Although these applications are new, carbon fiber has been around for nearly a century, Prado says. “Since we started using these materials in the 1930s, the process hasn’t really changed,” he says. “People make molds, they lay the fibers, and they get the same part out over and over again. That’s not something architecture is really good at. We don’t make the same building over and over again. We don’t make a mold of an entire building.” This process enables new ways of designing and fabricating composite materials in architecture.

Concrete + avant garde

A concrete panel formed by milling sand
Sand-milling process used to form concrete panels for DE|stress. Image courtesy of Christopher Battaglia.

Battaglia’s installation, called DE|stress, designed in collaboration with Martin Miller of Cornell University/Antistatics Architecture, also transcends traditional mold-fabrication methods. His pavilion will comprise 110 curved concrete panels, each unique and cast from the same material. The key is its green-sand casting method, in which panels are tooled in a wet and unfinished state. (The name “green sand” comes from the fact that the sand mold is not set; it’s still in the “green,” or uncured state.)

First, silica sand and bentonite clay are mixed with water. The water and clay bind the sand, making it pliable. The sand is compacted, then a CNC robot mills out the curved-panel geometry. Next, a fine-aggregate concrete is 3D printed in layers into the mold. After curing, the mold can be decomposed and the material recycled. It’s an extremely efficient process. (The project was created with support from sponsor Laticrete Concrete.)

A concrete panel features angular accents.
A concrete panel used to construct DE|stress. Image courtesy of Christopher Battaglia.

“The same robot that is printing the material is also creating the mold for the material,” Battaglia says. “There’s no material waste in the form-making at all.” The resulting panels serve as hollow bow-tie frames that lock into place through natural compression forces, forming a pavilion 35 feet long and 9.5 feet tall.

With the right amount of water in the mix, the green sand can remain rigid for weeks. “By concrete 3D printing into these precise molds, you get really sharp edge conditions, so now, even though the interior is printed, you’re getting the precision of a casted edge,” says Battaglia.

Multiple angular panels converge in a sculpture.
The DE|stress installation comprises 110 panels. Image courtesy of Christopher Battaglia.

With DE|stress, Battaglia has a specific sector of construction in mind. “It’s a critique on the prefab-concrete industry,” he says. Often, concrete panels are dull standbys selected for sturdiness but (especially at larger scales) rarely for geometry and form. Combining green-sand molding with 3D printing offers much more formal variation and flexibility while retaining concrete’s strength, making the material an ideal crossover between structural and facade systems. Battaglia envisions it eventually being used for facade systems and roof structures.

In the past few decades, Frank Gehry and other architects have gone wild with exquisitely warped steel-panel shapes fabricated by Zahner and others. It’s easy to imagine Battaglia’s process opening the same doors for concrete.

Both Battaglia and Prado’s experiments in Columbus point to a future where greater formal freedom is granted to materials, one where these broadened horizons are used to express both functional structure and aesthetic surface. When merging structure and surface, it’s possible to also envision merging their respective purposes (function and aesthetics)—another long-standing dream of the modernist pioneers in Columbus and worldwide.

Zach Mortice

About Zach Mortice

Zach Mortice is an architectural journalist based in Chicago.

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