Casting stones
Houston native’s ‘armadillo’ limestone vault joins architecture exhibit in Venice, Italy.
They call it the armadillo, pieces of limestone of varying size formed into arches, left to right and front to back.
It’s beautiful and magical, a wonder of engineering so simple you can’t imagine it hasn’t been done before and so complex you can’t believe it’s been done at all.
This work of architectural art — a free-standing, compressiononly stone vault — is among the 88 works on display at the prestigious 15th annual International Architecture Exhibition, la Biennale di Venezia, through Nov. 27 in the Corderie dell’Arsenale in Venice, Italy.
“Armadillo Vault” is the work of Houston native David Escobedo, who grew up learning home-building skills from his father, and Philippe Block, who did an internship at Escobedo’s company in Buda while earning a Ph.D from Massachusetts Institute of Technology (MIT).
The idea for the limestone armadillo was hatched by both men, but it took each of their unique skill sets to pull it off. Escobedo, a homebuilder, is something of a stone whisperer, able to manipulate stone in hard-to-imagine ways. Block, an engineering brainiac who runs the Block Research Group at the Institute of Technology in Architecture at ETH Zurich, wrote the software that guided them through the process. A third party, ODB Group an engineering group that includes Block, John Ochsendorf and Matthew DeJong, contributed to the engineering effort.
Escobedo said they call the structure an armadillo because they want everyone to know that it was born and raised in Texas.
“It’s alive. It’s on its own,” Escobedo said. “It’s standing there — the centering is gone, and it’s true compression — stone against stone.”
Using plywood and 30 tons of Texas limestone cut into 399 pieces, the men created a puzzlelike frame into which the limestone pieces sat. Steel beams kept it all in place, 40 feet by 60 feet and 14 feet high.
Then the beams and plywood frame were removed, and the pieces of stone, ranging from 40 to 340 pounds, were locked together through compression and gravity. No mortar, no fasteners of any kind — just stone, put together using Old World building principles.
“It’s a simple structure, but it’s an arch,” Escobedo said. “The more pressure you put on an arch, the stronger it gets.”
If Escobedo’s description in layman’s terms makes this sound simple or easy, just know that it is not.
“Engineering-wise, it’s taking basic principles from the beginning of time to what the computer says you can do now,” he explained. “Philippe’s software came into play. The highest level of engineering is going on here. ”
The idea was conceived in their heads and planned on computers, but then they had to test it. To take the idea to this exhibition — to which very few Americans were invited — required practice.
With just one week to spare, Escobedo’s team members finished cutting and assembling it in Buda. Then they took it apart and shipped it to Italy, where it would be rebuilt in an 11th-century building so carefully protected that they couldn’t use machine-operated tools inside. Everything was done with simple hand tools.
Altogether, it took five months of labor, some of it working 12 hours a day.
“Without the experience of my company, I would challenge anyone else to try to do what we just did — and I’m not a horn tooter,” Escobedo said. “I’m very modest, but, wow, that taxed everyone in my group even myself.”
So far, this armadillo might just be stealing the show in Venice. Escobedo said that jaws drop when people discover that gravity is the only glue involved in keeping the vault upright.
“Engineers from all over the world are sitting there with their mouths open,” he said. “‘It should not be possible.’ I heard that more than once.”
Near the end of the year, when the exhibit’s over, Escobedo hopes he’ll be packing up the structure for a new owner, perhaps an arts patron who also appreciates the science that’s involved.
For his part, Escobedo said he and Block imagined the impossible and then figured out how to make it possible.
“As we like to say, ‘Let’s do something (amazing), something no one has ever done,’” Escobedo said. “With my skill set and his, it happened.”