Gironde Estuary: Is Mud a Possible Resource for Construction? Advances from a Research Group

Making silt a material of the future is the goal of the scientific and artistic collective that took over the Maison de Grave in Verdon-sur-Mer for several weeks. The stakes are high: millions of tons of alluvium must be dredged each year from the Gironde estuary.

Bricks do from vase. Tiles. Enamel. From June 21st to August 31st, 2025, a team combining scientific and artistic skills is exhibiting the fruits of its research work on alluvium at the Maison de Grave, in Verdon-sur-Mer. This is because this material, often considered useless and problematic, is found in very large quantities in the Gironde estuary .

"We're talking about a mud plug. In fact, you have to imagine that these particles, which come from soil erosion, are carried by the river. When this fresh water meets the salt water of the ocean, a precipitate forms. The sediments then begin to settle," explains Mélanie Bouissière, architect and ceramist, member of the collective. Alluvium carried by the Garonne and Dordogne rivers silts up the estuary in very large quantities: one and a half to three million tons of suspended particles are deposited in the Gironde each year.

That much sediment will need to be dredged. "To ensure the navigability of the estuary and the Garonne, boats suck up the material year-round, seven days a week, " assures Quentin Prost, a team member and doctor of architecture. It's a simple operation, but a painstaking task: beneath the boat's hull, a long trailing tube—the suction tube—slowly scrapes the bottom of the channel. A pump sucks up the silt. The operation restores tens of centimeters of depth and ensures the boats' navigability in the channels.

Nearly 10 million cubic meters are sucked up and… discharged further out to sea

In the Gironde, the operation is fundamental, and the quantity excavated is very significant. Not only is the mud plug very active in Europe's largest estuary, but the Port of Bordeaux, which specializes in the trade of liquid and solid bulk, accommodates large vessels. Dredging, managed by the Grand Port Maritime de Bordeaux, is therefore a major undertaking each year: nearly 10 million cubic meters are sucked up and... discharged further out to sea.

A situation that spurred the collective's work: "The idea was to see if this material could be a resource for construction. Instead of dumping the mud [dumping substances into the sea, editor's note], why not use it?" confides Quentin Prost, who has just defended a thesis on the use of dredged sediment from the Arcachon basin in construction.

In the exhibition entitled " Alluvial Lands ," hosted at the Maison de Grave, we see the results of their research on mud: raw earth bricks, terracotta bricks that look exactly like their counterparts from earth's clay veins, and even glazed tiles and extruded bricks. The black, soft, and sticky material is completely transformed.

"Today, we're working on prototypes. The goal is to be able to construct buildings with a wooden frame and mud brick walls," reports Quentin Prost. Beyond construction, the four partners are discussing other possibilities: making furniture from vases—trading counters, for example—or even enameled tableware.

The black, soft, sticky matter is completely transformed

"Faced with the ecological emergency, we wanted to explore how we could repurpose all unused materials," explains Esther Bapsalle, designer and ceramist. Beyond mud, the collective has gone even further to utilize unused waste from local production. We discover bricks that mix clay from the estuary with oyster shells from the Arcachon basin, or even colored coatings made from Bordeaux vine shoots. A project that is therefore deeply rooted in the local area and the region.

A commitment that appealed to Charlotte Hüni, the manager of the Maison de Grave Departmental Estate . "This site, which belongs to the Conservatoire du littoral and whose management has been entrusted to the Gironde Department, aims to enable environmental education and risk anticipation. We were therefore convinced by this project."

The project is now seeking to structure itself. "In September, we have a meeting with an accountant. We're looking for our business model," explains Quentin Prost. Partnerships are being formed with local businesses. The collective is exploring the possibility of a mobile brickyard, which would travel along the estuary and produce mud bricks for local projects. Two small construction prototypes have been set up, and a third is planned. It will soon be presented at Arc en Rêve, the Bordeaux architecture center.

A new exhibition, therefore, which will be important, as Esther Bapsalle assures us: "The prerequisite is also to raise awareness among people, to change the way they look at this material that is mud." An objective achieved.