In Burgundy, France, 17,000 tonnes of discarded foundry sand went beneath RN 80; two years later, tests found good road strength and no environmental impact

Beneath a section of the RN 80 highway in Burgundy, France, engineers tested whether discarded foundry sand could serve as a component of road construction. However, under a section of the RN 80 highway in Burgundy, France, engineers have found a way to use thousands of tons of foundry sand waste not as landfill but as an actual component of the road. This unique experiment gave engineers a rare opportunity to check how a waste product performs when subjected to everyday traffic.

A study published in Construction and Building Materials reports that approximately 17,000 tonnes of discarded foundry sand were used beneath the RN 80 highway in Burgundy. The field application was carried out during the construction of the RN 80 road section, and researchers monitored its performance for two years before publishing their findings. Two years later, researchers reported that the road had performed well structurally without any environmental hazards identified through the tests.

Turning industrial waste into road foundations


Foundries use specially treated sand molds to shape molten metals into finished components. With time, a large amount of this sand is no longer fit to be used in production and therefore becomes a waste product that needs to be disposed of properly. Instead of sending all of it for disposal, engineers explored whether the material could serve another purpose beneath road pavements.

About 17,000 tonnes of foundry waste sand were incorporated into the sub-base and base layers of the road during construction. About 17,000 tonnes of foundry waste sand were added to the sub-base and base layers of the road during construction, allowing researchers to monitor the material under real traffic conditions.

Two years of real-world testing

Constructing a road using recycled materials is just the start, as the engineers have to determine whether the material will perform well even after several months and years. Researchers monitored the RN 80 section for two years, evaluating both its mechanical performance and its environmental behavior. The mechanical parameters showed that the structural strength of the road remained good throughout the observation period, indicating that the recycled material continued to support the pavement effectively. The study also examined whether substances from the foundry sand could affect the surrounding environment. The assessment detected no significant ecological impact during the two-year evaluation period. The findings suggested that recycled foundry sand performed well in practical use and did not raise environmental concerns during the study period.

Why recycled materials are attracting attention in road construction

Road construction requires enormous amounts of natural aggregates on an annual basis. As governments and industries seek to minimize wastage and save natural resources, there have been increased efforts to utilize industrial by-products where appropriate in construction projects. The use of recycled industrial byproducts in construction reflects wider efforts to reduce waste generation and limit dependence on newly extracted resources. For construction projects, that means carefully evaluating whether industrial byproducts can safely replace conventional materials without compromising performance or environmental protection. In the case of the Burgundy project, it is evident how such assessment is made in practice.

Rethinking what infrastructure can be built from

The RN 80 highway project reflects a broader engineering effort to use industrial waste as alternative raw materials. Each field test will add practical experience regarding the locations in which recycled materials can be used safely. This approach could help reduce landfill use and demand for new construction materials. Monitoring of roads using recycled materials is also important in order to check whether recycled materials are meeting the necessary performance criteria. Beneath a stretch of highway in Burgundy, thousands of tonnes of discarded foundry sand found a purpose that few would have imagined. Instead of being discarded, the material became part of the road foundation.