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Researchers lead the way in giving a second life to concrete waste

03.07.2015

In France, building demolition works and public works comprise the leading source of waste with some 260 million tonnes per year, a large portion of which is concrete. In order to develop its recycling, a collaborative R&D programme, Recybéton, was initiated after three years of research. A first assessment shows the technical reliability of the use of dismantled concrete in new works.

Credits: UNPG

After being crushed in one of 200 specialised recycling platforms, recycled concrete is currently used primarily in road construction. The ambition of Recybéton, the research programme supported by the Ministry of Ecology and the ANR (National Research Agency) which includes about forty public and private partners, is to transform used concrete into a secondary raw material in order to produce new concrete. To do this, engineers and researchers work together to resolve the technical difficulties encountered in the use of materials from dismantled concrete (such as cracking, significant water absorption, alkali reaction that generates concrete swelling). Another research axis also focuses on the use of material from dismantled concrete in the production of cement. After the laboratory trials, several full-scale experimental worksites were also put into place. Near Lyon, for example, a 2,100 m2 parking lot using pavement with recycled concrete was successfully constructed.

Armed with the past three years of research, Recybéton believes that “the industrial feasibility of recycling concrete has been proven.” The project initiators are banking on the forthcoming creation of a circular economy of concrete, with many benefits. In fact, difficulties in opening new quarries because of administrative or environmental constraints renders the aggregate less and less accessible. The use of recycled aggregate, which often requires less transportation between its place of production and place of use than natural aggregate, would result in further reduction of carbon consumption and thus greenhouse gasses. Potential and needs are finally coming together. Numerous structures built during the “Glorious Thirties” are finally reaching the end of their lives while projects such as those of Grand Paris, for example, should grow the consumption of aggregate in the Île-de-France region by five million tonnes per year.