Cracks in the roads, sometimes subsidence, like ruts.
The phenomenon is becoming common on the roads of France: it is due to the movement of clay under the road.
If the summer of 2021 is the exception for the moment, our road network is suffering from climate change, and in particular the repetition of episodes of heatwave and drought, as during the summers of 2020 and 2019.
"In the Loiret, on 3600 km of road, 30% are affected by these incidents of withdrawal and swelling of the clay", specifies Frédéric Leguay, responsible for the management of roads at the departmental council.
A new solution will be tested on the departmental road which links Pithiviers (Loiret) to the Montargis-Orléans axis.
The work is underway until next week near Ingrannes.
“Here, we even had breaks on the shoulder in 2019. This presented a danger for users.
We had to intervene urgently to repair the road, ”recalls the engineer.
Between Pithiviers and Orléans, a hardening liquid based on water, potash and lignin is injected by a drill into the deformed sub-layer of the departmental road.
Photo DR Loiret County Council.
DR
Probes and sensors over 400 meters
In partnership with the Center for Studies and Expertise on Risks, the Environment, Mobility and Planning (Cerema), the Loiret is testing a solution called Remediakay, patented by the American company Keller, and still unprecedented in Europe.
This involves injecting a liquid through a drill up to 2.50 m.
depth.
"This solution based on water, potash and lignin, extracted from wood, then solidifies on contact with the road sub-layer to consolidate it and neutralize the movements of the clay", explains Lamine Ighil Ameur of the Cerema.
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South of Pithiviers, on the D961, the renovation works extend over 5 km, but the part that will be equipped with sensors is only 400 m long. The Loiret department is funding this unique experiment in France and Europe at a cost of around 150,000 euros. Cerema, which has launched an Observatory of Drought-Affected Roads (ORSS) hopes to learn the first lessons by 2024. If of course the heat waves return. Several territories are closely following this test, such as Vendée, or the Breton departments.