ding crushed concrete
Every year, 20 million tonnes (Mt) of concrete waste from demolition is produced in France. Driven by the European objective - taken up in France by the energy transition law - of 70% recovery of building and public works waste, as well as by environmental and economic imperatives, the players in the sector are getting into battle order . “We are currently at the heart of a paradigm, between improving the recyclability of concrete on the one hand, and increasing durability on the other. We are therefore working in two opposite directions. contractors to put in place their own technical and economic strategies" , says Laurent Izoret, Deputy Director of Products and Applications at the Technical Association of the Hydraulic Binder Industry.récupération de béton 62% of concrete from demolition is recovered, mainly for road purposes or as backfilling for quarries. These materials could be better used and valued on larger projects, agree to say the professionals gathered Friday, October 7 in Paris within the framework of the Meetings concretes organized by the representative organizations of the sector. But technical, qualitative, regulatory and economic obstacles have been identified. The rate of substitution of virgin materials by recycled aggregates today ranges from 5% to 90% depending on the concrete and the companies. 8% of French production of aggregates comes from recycling, i.e. 20 Mt out of an annual total of 350 Mt. The quality of the materials in question The conformity of materials from demolition or deconstruction is a first obstacle, underlines Serge Favre, chemical engineer and concrete expert at Léon Grosse: "we choose the aggregates according to technical criteria, which dominate, and economic. The quality of the materials is directly related to the works to be done (engineering structures, metro tunnels, offices, housing, etc.) Good resistance, good plasticity and good facings must be achieved . crushed is four times more complicated, hence the usefulness of working well on the formulations" . The question of sorting the deposit upstream is also raised. "Demolition is not at all selective. We will end up with very mixed materials, with concrete, brick, other origins of materials, possibly wood or plastic pollution. Deconstruction, on the other hand, provides for to remove the elements one by one, to finally end up with the purest possible material, which will lead to a use closest to that sought in the aggregates industry", continues Sophie Decreuse, director of products and quality at Cemex France and representative of the National Union of Aggregates Producers.