This is a world first! In Gennevilliers, in Hauts-de-Seine, the social landlord Seqens, a subsidiary of the Action Logement group, and the cement manufacturer Holcim are currently building a building using entirely recycled concrete. The 2,200 tonnes of aggregates required (gravel and sand) thus come from waste from Parisian concrete plants and demolitions in the Ile-de-France region… including that of the former residence on the Brenu block, where the project is located. A model that couldn’t be more circular! The 2,000 tonnes of clinker, the majority component of cement, were, for their part, manufactured in the Alsatian Holcim factory, in Altkirch, from around ten reused products (wood ash, waste from the treatment of minerals, etc.). An operation which made it possible to save 10% of CO2 emissions, and, above all, nearly 3,000 tonnes of natural resources. Although the delivery of the 76 housing units in the building is not expected to take place before the end of 2024, the bet has already paid off for those involved in the project. “We pushed the sliders to the maximum, not only to increase our knowledge on the subject, but also to reassure the sector about the reliability of new technologies based on this type of material,” assures Flore Bellancourt, building market manager at Holcim France.
Consume as little planet as possible
This performance, which required a year of research & development, was made possible thanks to a change in regulations in October 2022. Until then, in France, it was hardly possible to integrate more than 15% of gravel. recycled in concrete, particularly for insurance purposes. From now on, the new standard allows, under certain extremely restrictive conditions, to potentially increase to 100%. “Our heritage constitutes a gigantic bank of materials. Thanks to it, and wherever we can reproduce this type of operation, we will do so, in order to consume as little of the planet as possible,” insists Franz Namiach, deputy general director of Seqens .
Today, 80% of concrete from demolitions is reused in France. However, this recycling is carried out most of the time for backfilling or road applications, and very little (less than 15%) for reuse in other buildings. The National Union of Quarrying and Construction Materials Industries (Unicem) has set itself the objective of achieving an inert waste recovery rate of 90% by 2025 and covering more than 30% of aggregate needs. for construction in France. “In an ideal world, we would like to build everything by recycling the materials from our old works, but we do not destroy as much as we build, so that it is impossible to meet all needs,” estimates Louis Natter, president of Unicem Engaged Companies, an association which encourages companies to integrate sustainable development into their activities.
The building generates 42 million tonnes of waste per year
However, there is no other choice than to make the sector more virtuous. The building alone generated, according to Ademe42 million tonnes of waste in 2020… a quarter more than all French households! According to the Ministry of Ecological Transition, the recovery rate of these different components (bricks, concrete, tiles, glass, stone, earth, aggregates, wood, plastics, metals, etc.) varies from 48% to 64%. Since the promulgation of the Agec law (Anti-waste for a circular economy) in February 2020, the State has sought to change the situation. At the heart of this text, the concept of “extended producer responsibility” (EPR) which, proof of the ambient inertia, has only been applied since January 1. Its principle? As was done in the area of household waste, producers of construction products and materials pay a financial contribution (depending on what they put on the market) to eco-organizations. It is up to the latter to set up a recycling, reuse and re-use of debris by taking it back free of charge, at the same time reducing illegal dumping. “Thanks to this upstream financing, we will more easily develop the capture and treatment of this waste. Which will further improve the competitiveness of recycled materials,” rejoices Louis Natter.
Ecominéro, one of the four approved eco-organizations specializing in minerals (concrete, stones, terracotta, etc.) already lists 1,400 recovery, sorting and recovery sites. “The key to success will be the coverage of the territory, to be as close as possible to the construction sites,” indicates François Demeure Dit Latte, its general director. According to him, the demand from the industry is already there, and there are not yet enough deposits of recycled materials to meet these needs. “Beyond the price, professionals are above all looking for environmental performance to fuel their decarbonization efforts,” underlines this former director of recycling at Suez, for whom the implementation of the sector will take two years.
Psychological obstacles to overcome
In Angoulême (Charente), window craftsman Yoann Simonet now removes up to 6 tonnes of joinery per month using this system. “Previously, we put the dismantled windows and doors in a dumpster. Which was a real waste and heartbreaking,” regrets the manager of the company of 11 employees. “The biggest challenge is to make this change in mentality towards circularity,” adds Marion Elisé, communications manager at Valdelia, another specialized eco-organization. Awareness of sorting on construction sites, facilitation of evacuation logistics, extension of insurers’ coverage to recycled components, confidence in the quality of the latter, etc., so many psychological obstacles to remove.
“We are still in the early stages today, but reuse in construction can really become a major trend in the years to come,” believes Catherine Guerniou, vice-president of the French Building Federation (FFB) in charge of the transition. ecological and manager of la Fenêtrière, a family carpentry business. As proof, Valdelia, Suez and the Les Canaux association launched last year, in the Bordeaux region, a “Circular and sustainable building accelerator” (ABCD). “Until January 2024, we will support 13 companies that are making the construction field more sustainable and circular, in order to help them develop,” explains Clémence Grunenberger, its manager. Among the winners: Etxe Berri, a general building company specializing in eco-construction, Keno, an architectural firm working to reduce waste and carbon impact, or even Tri’n’Collecta sorting, collection and recovery service for construction site waste.
Promising initiatives which are part of the lineage of young shoots in this sector with a bright future, such as the Minéka building materials recyclers in Lyon and Recyclo’Bat in Toulouse, or the online platform Ubeton, which offers unused concrete at knockdown prices to craftsmen. “Every working day, the equivalent of 1,000 mixer trucks are not used,” says Olivier Billa, its co-founder, a former site logistics manager saddened during his career by so much waste. A solution had to be found.” A second life that is good.