The Rolls-Royce of Concrete

When the Paris firm Emmanuel Combarel Dom­i­n­ique Marrec Architects won a competition to design a bus depot in Thiais, on the outskirts of the city, it wasn’t exactly getting a prestige project. The pro­gram was strictly pragmatic—Paris’s transport agency needed the center to accommodate 300 buses, plus administrative offices—and the setting far from glamorous. “We could sum up this area by saying it’s a pretty shitty suburb,” Dominique Marrec says. “It’s very lousy all around.”

Still, the architects wanted to create something tied to the site’s specific context, even if that was little more than vast expanses of concrete. Emman­uel Com­barel and Marrec eventually conceived of a two-story building that would rise out of the parking lot, a sort of “deformation of the soil.” For the cladding, they chose Ductal, a high-performance concrete invented in the 1990s by the French building-materials company Lafarge. “We liked the idea of using this very high-quality concrete—in a way the Rolls-Royce of concrete—in an area that’s mostly poor-quality asphalt,” Marrec says. “The opposition of these two aspects was very inter­esting to us.”

Besides possessing the strength and moldability necessary to form precast slabs for the roof and walls, Ductal allowed the architects to design a raised-dot texture that resembles Lego blocks. The material was tinted black to match the surrounding asphalt and given a layer of varnish for an even tone. If the result looks a little sinister, Combarel and Marrec don’t mind. “We wanted something pretty rough and virile—not feminine at all,” Mar­rec says. “We wanted it to look mean.”

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Composition
Ductal is a cement-based composite material with metallic or organic fibers.

Properties
It has exceptional strength, moldability, durability, and ductility (the ability to deform while continuing to carry loads). Surface textures and colors will not deteriorate, even in harsh conditions.

Applications
Bridges, walkways, building envelopes, acoustic sound panels, flooring

Distributor
Lafarge North America
(866) 238-2825
www.lafargenorthamerica.com
www.imagineductal.com