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Civil Engineering Magazine THE MAGAZINE OF THE AMERICAN SOCIETY OF CIVIL ENGINEERS

Delicate Pavilion Is Printed in Concrete

By Catherine A. Cardno, Ph.D.

The 840 unique blocks that form "Bloom," a 9 ft tall tempietto , have been printed using a 3-D printer and a powdered cement polymer composite.

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“Bloom” is a concrete pavilion—a tempietto—formed from 840 unique concrete blocks that have been printed using 3-D printers and a powdered Portland cement composite. Courtesy of UC Berkeley

March 17, 2015—Concrete can be described in many ways. Delicate is not typically among them. But "Bloom," a tempietto unveiled at the University of California, Berkeley, may change all of that. The 9 ft tall undulating structure not only has an exterior modeled on a lacelike motif of traditional Thai flowers, which allows light to permeate the structure's exterior, it also redefines the capability of concrete as a material.

"'Bloom' represents a continued line of ongoing research—six years—into the possibility of creating durable, strong, and inexpensive materials for use in architecture," said Ronald Rael, an associate professor of architecture at the University of California, Berkeley, who created the pavilion. Rael wrote in response to questions posed by Civil Engineering online.

The tempietto was created from 840 unique concrete blocks printed by 3-D printers and bolted together with stainless-steel hardware. Measuring 9 ft tall and appearing as a 12 ft by 12 ft clover leaf in plan, the top of the pavilion is turned 90 degrees from its base to give the entire pavilion an undulating, twisted shape. The twist creates a torqued "x" shape, with an entrance located 45 degrees from the structure's axis, according to material provided by Rael.

A group of 11 3-D printers created the bricks using a powdered, iron oxide-free portland cement composite with a plant-based, ultraviolet light-resistant polymer. Without the iron oxide, the Portland cement gives a much lighter, brighter hue to the finished product. 

Each block was formed individually so that the result is a very delicate pattern—and a structure far larger than the machines used to create it. "'Bloom' demonstrates the feasibility of building using 3-D printing in ways that are precise, beautiful, meaningful—and structural," Rael said. 

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Each of the blocks is uniquely shaped, creating a lacelike pattern of traditional Thai flowers on the exterior and a printed structural grid for the interior of the tempietto. Courtesy of UC Berkeley

"Each block has a printed structural grid that defines the interior of the tempietto and requires no additional structural support, functioning as a load-bearing, 3-D printed enclosure," Rael explained. "The curvilinear shape gives added stiffness to the thin, lightweight structure." 

The design was inspired by three undulating, thin structures, according to Rael: Uruguayan architect and engineer Eladio Dieste's work with masonry, particularly his Iglesia Cristo Obrero in Atlántida, Uruguay; President Thomas Jefferson's elegantly undulating brick walls at the University of Virginia, in Charlottesville; and American sculptor Richard Serra's circular, curving steel piece, Torqued Ellipse .

While the form of the tempietto is impressive and the creation of the individual bricks complex, there is something more fundamental that sets this concrete structure apart from typical concrete creations: "In the United States, 60 percent of the cost of a concrete structure is in the formwork," Rael said. "3-D printing with cement does not require formwork, thereby reducing waste, and potentially cost, as well as having the possibility to create shapes that are not possible to make with traditional methods. 

"Every part of this is unusual when compared to traditional construction methods that employ cement," he added. "Very little water is used. No formwork is needed. Parts can be created with undercuts." 

While there are a few people in the world experimenting with 3-D printing with cement-based materials, "all are extruding wet cement through a nozzle to produce rough panels," according to a statement made by Rael and released by the university. "We are mixing polymers with cement and fibers to produce very strong, lightweight, high-resolution parts on readily available equipment. 

"It's a very precise, yet frugal technique," Rael continued. "This project is the genesis of a realistic, marketable process with the potential to transform the way we think about building a structure."

The tempietto was unveiled on March 6 at the Berkeley campus as part of its "Berkeley Circus," which celebrates the research and accomplishments of the College of Environmental Design. 

Funding and collaborative support for the project was provided by the Saraburi, Thailand-based Siam Research and Innovation Co. Ltd. (SRI), the research and development division of the Bangkok, Thailand-based Siam Cement Group, which itself is the largest cement company in Thailand. 

After its unveiling in Berkeley, the tempietto was dismantled and sent to SRI for the start of a worldwide traveling exhibition.

 

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