The manufacture of this mortar for filling a quarry, was made from oyster shells.

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Roberto Giostra, Department of Gironde

  • On Wednesday, the Gironde departmental council experimented with the use of the oyster shell as a replacement for sand in the manufacture of a mortar.

  • A Bordeaux association is working with a laboratory to create a shell-based construction material.

  • Collections will be organized during the holidays to prevent the shells from ending up in household waste.

Stop, no longer throw your oyster shells in household waste.

Collection points will be set up during the end of the year celebrations, in Bordeaux and in the Arcachon basin, to recover this shell for which there are more and more outlets.

The latest?

The Gironde departmental council has just tested the crushed oyster shell, replacing sand in the manufacture of a mortar which is used to fill underground quarries, located under certain departmental roads.

A Bordeaux association is working on making it a building material.

25 tonnes of oysters for a volume of 65 m3 to be filled

On Wednesday, 25 tons of oyster shells were used to fill a volume of 65 m3 of a quarry in Prignac and Marcamps.

“Rather than using sand extracted from quarries or rivers, the idea is to find a substitute material, and we looked at the oyster shells, grinding them to give them a particle size that corresponds to that sand ”, explains the vice-president of the departmental council responsible for preserving the environment and road infrastructure, Alain Renard.

“There is an additional cost of the order of 20 to 30% compared to the use of sand, recognizes the elected official, but it is because the sector is not organized, as soon as we will pass on another scale, these costs will be lowered.

And at the same time, it saves money in other areas, such as waste disposal.

"The next project planning to use this shell-based mortar is located in Entre-Deux-Mers and would concern around 1,000 m3," which is starting to generate significant volumes for these oyster shells.

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Dumpsters available in eight waste reception centers in the Arcachon basin

To recover as much as possible, the department has joined forces with the communities of municipalities in the Arcachon basin, to encourage individuals to bring back their oyster shells for valuation during the holidays.

Dumpsters will be at their disposal in eight waste reception centers in the Arcachon basin from December 19 to January 3.

On the Bordeaux side, things are also moving to collect shells from individuals, such as restaurateurs.

As soon as they reopen.

The Coquilles association will therefore organize a collection operation in the Bacalan district, also from December 19.

A voluntary drop-off point will be set up next to the Bacalan oystercatcher stand where consumers can drop off their empty shells.

The 120-liter bin will be collected twice a week by the Detritivores, partner of the operation.

Special shell totebags will be given to consumers to encourage them to bring back their empty shells.

Objective: recover 25 tons in six months in Bordeaux

For now, it is only a small collection, which aims above all to make the association known.

But this one thinks big.

“In 2021, we would like to conduct a six-month experimentation phase at the scale of the Bordeaux metropolitan area, with around twenty voluntary supply points for individuals, and with partnerships with professionals: restaurateurs, food shops , fishmonger…, explains the president of this young association, Bénédicte Salzes.

The target is 25 tonnes of shells collected over these six months, and valued by market gardeners and wine growers in the region.

In agriculture, the oyster shell is effectively used as a calcium soil amendment, an alternative to lime which neutralizes the acidity of the soil.

“We also have a research and development component, thanks to a partnership with the I2M university laboratory, to launch shell-based construction materials.

The association is also in partnership with the company Eaux-Vives, a player in the recovery of shellfish waste in Charente-Maritime, and which offers to crush oysters on site using a mobile crusher.

The idea of ​​the association "germinated in the spring of 2019", explains Bénédicte Salzes.

“It starts from the observation that an oyster shell has nothing to do in a trash can since household waste is generally incinerated and a shell does not burn.

»This while it is valuable in several ways, since it also serves as a food supplement for chickens and is also used in chemistry for the manufacture of cosmetics.

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