Flagship project / Making the regional supply of building materials in France more sustainable
Urban expansion and changing lifestyles are increasing demand for building materials. To satisfy regional supply requirements more sustainably, the resources used should increasingly combine raw materials from quarries (primary materials) with recycled construction waste (secondary materials). This is especially important since construction waste represents a large proportion of France’s annual waste production, and consists predominantly of inert materials, which can be reused for other purposes. However, recycling cannot cover all needs, and primary resources must still be produced.
Optimising and streamlining the management of resources
BRGM’s expertise spans the entire value chain for construction materials. For example, it manages the CARMA database (on quarries and materials) to assess primary resources. It provides access to this database on the mineralinfo.fr portal. BRGM is involved in the development of the regional quarry master plans, which now include recycling platforms, and helps to quantify needs and assess material flows and sources of potentially recoverable waste. "We develop methodologies for optimising and streamlining the management of all primary and secondary resources," says Sébastien Colin, a georesource geologist. "Among other advantages, the methodologies support high-value uses for quarry materials and the conversion of more quarry by-products."
At the same time, BRGM is working on the recycling of construction waste by developing innovative technologies to improve the recovery of valuable materials from this waste. An example is the reclamation of waste ultra-high performance fibre concrete, which was studied as part of the HISER European project, which ran from 2015 to 2019. "This new type of concrete has exceptional properties due to its metallic fibres. But these prevent it from being recycled using traditional processes," explains Kathy Bru, a project manager and process engineer. Trials conducted by BRGM show that the fibres can be extracted without altering their properties. "We have successfully tested electro-fragmentation. This process separates the metallic fibres, which can be reused to manufacture new fibre concrete materials, from the cement-rich fraction, which can be used to produce traditional concrete." Although further work is needed to improve feasibility, the economic and environmental benefits of this process have been confirmed.
Determining the best use options
The recovery of excavated earth and materials, which make up the bulk of construction waste, is also a subject for study by BRGM. Since 2018, within the AGREGE project team, BRGM has been investigating how excavated earth can be used to produce highly fertile urban soils. "The project focuses on selecting promising waste containing expansive clays and fine particles (thereby creating a new market for these materials), identifying local sources and mixing components in the right proportions to produce fertile soil," says Philippe Bataillard, a soil geochemist. The project’s long-term objective is to develop a soil restoration industry for urban development. It has already identified two waste materials that can be used in this context: thermally treated sewage sludge and quarry pond fines, a by-product obtained from the washing of aggregate, which has not been needed until now.
Lastly, BRGM is developing a foresight approach to resource management. In the Provence-Alpes-Côte d’Azur region, for example, it participated in the development of the regional quarry master plan and took part in the national OVALEC project. "We are working on quantifying the share of local supply which could be sourced from recycled construction waste to reduce the extraction of primary resources," says Daniel Monfort, an environmental engineer. "By comparing the environmental benefits and impacts of extractive activity versus recycling, we will be able to select the best use options for primary and secondary materials in each region. Recovering waste to replace primary resources is always commendable and beneficial, but even more so in regions that are heavily dependent on the sourcing of materials from neighbouring regions."