VALORIZATION OF CONSTRUCTION, DEMOLITION AND INDUSTRIAL WASTE, A ROUTE TO CIRCULAR ECONOMY

Building and construction sector represents a large part of global resource consumption and of solid waste production (one third of all waste produced in EU). Therefore, the resource efficiency and management is crucial in this domain. A very significant part of the construction and demolition waste (CDW) is not recycled today, and the construction and building products and materials include only a very limited part of recycled content. To address these issues, our team is involved in different projects supported by European and regional funds. The first one is ECOLISER, a research project in the field of alternative binders that are more ecological and economical, for the treatment of the mechanical stability of soils and for their waterproofing (funded by FEDER and the Walloon Region). Theses eco-binders are developed from industrial by-products or secondary materials such as slag, bottom ash, glass fines, fly ash... The second one is the VALDEM project, which aims to optimize buildings end of life management by developing new deconstruction, sorting and recycling processes. The goals are to produce uniform and accessible material flows, and then to increase up-cycling applications and valorization of CDW (funded by Interreg FWVL European Fund and the Walloon Region). It focuses its activities in North of France, Flanders and Walloon regions (Belgium), and stands out from usual approaches by its cross-border view of circular economy. It also strives to validate the solutions from technical, scientific, economic and environmental point of view. Besides these projects, we have used the results of another research project, CONREPAD (BEWARE fellowships), in which some VALDEM operators were involved (ULiège – GeMME, Prof. Luc Courard). The theme is the recycling of waste concrete blocks manufactured by the PREFER company (Belgium), and in particular the substitution of natural aggregates (NA) by crushed waste blocks as recycled concrete aggregates (RCA). The CONREPAD study determined that the integration of 30% of RCA did not alter the mechanical properties of the blocks and was therefore conceivable (B_RCA30 blocks). A comparative LCA is to made to evaluate the impact of the recycling process of the block waste, and to assess the influence of their integration in the making of the blocks in substitution of the NA, in comparison with to the "business as usual" process (NA only). The results do not show significant gain in any impact category because of the very low available amount of waste (1%), as the internal production of RCA added in B_RCA30 blocks can only substitute 3% of the global production of Prefer. An alternative scenario, based on the import of external RCA from a nearby CDW sorting site, shows however a potential gain in all categories, especially in the Land use category (up to 11.5%) if the total production of blocks consists of B_RCA30. In conclusion, globally and in a circular economy perspective, the substitution of NA with RCA from internal production waste blocks and external source of CDW, is an interesting development route to improve the environmental impact of the concrete blocks made by Prefer.Valde