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Concrete Protects Marseille Museum
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Exterior rendering of the Museum of Civilizations
To celebrate its designation as the 2013 European Capital of Culture, the City of Marseille is opening the Museum of Civilizations from Europe and the Mediterranean, dedicated to the rich culture of the Mediterranean region. Getty Images

On the occasion of its designation as the 2013 European Capital of Culture, the City of Marseille, France, has unveiled a spectacular new museum on the Mediterranean Sea that is protected from exposure to saltwater by ultra-high-performance concrete.

July 16, 2013—Marseille, the French port city overlooking the Mediterranean Sea, has been designated by the European Union as the 2013 European Capital of Culture. To celebrate, the city is hosting events throughout the year. It is also taking the wraps off of an expansive new museum project: the €113.4-million ($U.S.148.2 million) Musée des Civilisations de l’Europe et de la Méditerranée (Museum of Civilizations from Europe and the Mediterranean) or MuCEM. Drawing on collections from two predecessor institutions, the Musée National des Arts et Traditions Populaires and the Musée de l’Homme, MuCEM will house a staggering collection of 250,000 art and cultural objects, 500,000 photos, and 110,000 prints, all dedicated to the rich cultures and civilizations of the Mediterranean region.

The museum is divided between a new building, on the city’s old J4 pier, and the renovated Fort St. Jean, a military complex adjacent to the pier that dates to the 12th century. A footbridge that slices across the edge of the sea joins the buildings.

The J4 building is a square structure sheathed on two sides and the roof with a stunning façade of filigreed ultra-high-performance concrete (UHPC). The concrete façade serves as a sunshade for the museum itself, eliminating the need for blinds, but it appears to be much more. It’s as if charcoal-colored lace curtains were diffusing the building’s mass in a complex array of light and shadow, making the structure seem both tangible and transparent. The façade also helps create a perimeter walking path around the museum’s central exhibits, which will allow visitors, in the quirky phrase of the museum’s own description, to “demuseumify” themselves and catch fragmented views of the fort and the sea. 

Aerial view of the MuCEM's new building, which is connected to the historic St. Jean Fortby a think and light 120 m long footbridge

The MuCEM’s new building is connected to the historic St. Jean
Fort by a think and light 120 m long footbridge, which is
constructed of a series of 25 UHPC elements.  © Agence
Rudy Ricciotti

Architect Rudy Ricciotti won the competition to design the museum in 2003 (the design work actually began in 2002), but work didn’t really begin until 2010. The intervening years turned out to be crucial, in that they afforded Ricciotti’s firm time in which to fine-tune its research into UHPC. “It was kind of an internal research program,” says Tilman Reichert, the project manager for Rudy Ricciotti Architecte, and the supervisor of the architectural aspects of the project. That research lasted for several years. “We invented some parts of this project,” he says. “Now let’s figure out how to do it. This was finally the reason that when we started to build in 2010, we were ready to start.”

UHPC is not reinforced with traditional rebar but instead reinforced with very dense steel fibers, only 2 to 4 centimeters long. In that way, Reichert explains, UHPC works like traditional horsehair-reinforced clay. In a written document, Ricciotti further describes the concrete: “The presence of fibers in the UHPC allows the structure to free itself from the passive steel and thus causes the elimination of coating layers and the reduction of the structural thickness.” For instance, it is possible, he writes, to create ultra-thin bridge decks. Additionally, “by reducing the amount of material to install, the time of handling and implementation such as for a lattice, for example, is also decreased.”

Reichert says that the compression resistance of UHPC is five to eight times greater than normal concrete. With the latter, you can “charge” concrete by 500-700 kilograms per square centimeter; in laboratory conditions UHPC enables conditions compression at 3 or 4 tons per square centimeter.

Ricciotti further notes that the concrete, “which fears neither corrosion nor dirtying,” resists pollutants, wear, and abrasion. “In some high environmental quality standard areas targets, it is more efficient than steel,” he writes.

Thinness and pollution resistance are not the only benefits. UHPC also has superior waterproofing characteristics compared to ordinary concrete. The largest grains of UHPC have a section of less than 1 mm. This is important in climates in which concrete is exposed to salt water—at the edge of the Mediterranean, for example. Salt water can infiltrate normal concrete and start oxidizing rebar. Reichert calls Marseille “a corrosive climate, [a] rusty climate,” and therefore its concrete is vulnerable to the microprecipitation of sea spray. “It’s the danger of every concrete structure on the seaside,” he says. On other projects Ricciotti uses UHPC for roof construction with waterproofing.

Night view rendering of the museum, which is located at the edge of the Mediterranean Sea

The MuCEM is located at the edge of the Mediterranean Sea,
and the UHPC used in the building’s construction helps resist
seawater corrosion. ©Agence Rudy Ricciotti

But UHPC is not widely used. “It is not easy to build with, it’s not easy to design with,” says Romain Ricciotti, an engineer for Lamoureux & Ricciotti Ingeniere, the small firm that carried out the structural studies for the construction. “If you miss one detail it becomes very expensive.”

But the concrete filigree sunshade of the museum’s exterior also shows the potential of the material. The filigree is made of a series of 6 m by 3 m panels, only 10 cm thick on the facades and a mere 7 cm thick on the roof. The panels were designed then tested and modified on the basis of whether they would function structurally. “There’s not one decorative piece in it,” Reichert says. “Every piece participates on the structural load.”

Though the filigree appears entirely organic and random, the panels reproduce a handful of forms, which can be rotated to link with the other panels in a variety of ways. Ricciotti notes it was critical that the components be precast accurately to avoid shrinkage, “so you can mold it like a cake,” he says. “The mold needs to be a little bit flexible to avoid cracking.”

In addition to the filigree, the museum utilized another “organic” looking structural system: a series of columns that support MuCEM’s exhibition spaces. With help from a cabinetmaker, engineers designed a catalog of nearly two dozen shapes that could be fitted together like Legos. The column shapes, which do not go straight up or down but rather bend like the branches of a tree, constitute the main vertical structure. These UHPC columns, prestressed by posttensioning, can be compressed by up to 180 tons, reducing the weight of the structure, reducing seismic loads, and increasing transparency.

Ricciotti’s firm designed a catalog of nearly two dozen treelike columns, the shapes of which could be fitted together in different combinations. The columns were made of wood, and with help from the cabinetmaker builders created the molds and prefabricated the 340 UHPC column pieces with a dimensional tolerance of less than 1 mm.

Interior view rendering of museum, displaying its concrete lattice façade

The concrete lattice façade also helps create a perimeter walking
path around the museum’s central exhibits.  © Agence
Rudy Ricciotti

At the top of the new J4 building, a thin 120 m long footbridge extends over the waterfront to connect with the historic St. Jean Fort. The bridge, which has a span of 80 m, is constructed with a series of 25 UHPC elements, each about 4.5 m long, joined by a series of cables and placed under tension until the elements form a structural system that behaves like a beam. Due to its high compression strength the bridge is quite thin and light and, again, an effective barrier to salt water.

Reichert notes that because UHPC is not considered a standardized material, designers and engineers on the project had to go through a procedure known as ATEX, or approbations technique experimental, which requires builders to establish the technical quality of new materials or construction processes. Engineers had to explain to a commission of experts that the process would in fact work.

“We explained to the commission how we would do it, justified how it would work, on which elements we’d have to make some tests,” says Reichert. The commission’s blessing would enable the building to be properly insured. Fortunately, the minister of culture, the official client for this project, was a supporter. “From the beginning he considered that innovative architecture and construction is part of culture, and UHPC specialists on his project team allowed him to appreciate the technical expertise that we were proposing,” Reichert says.

Both Reichert and Ricciotti anticipate that UHPC will continue to grow in popularity, but don’t expect it to be used in mass production just yet. Reichert says the firm insists that innovative architectural and technical projects serve both as an engine for local economies and the valorization of engineers’ expertise.

“You need experts and engineers who know how to work it,” he says. “You need craftsmen. You can’t buy it.”


 

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