Circular economy in the construction industry: An insight into the difficulties and possibilities with improving the concrete recycling rate for housing in Sweden

Abstract: In accordance with the Paris Agreement and the national goal of climate neutrality by 2045, Sweden needs to lower its greenhouse gas emissions. The second-largest source of CO2 emissions in the country comes from the production of cement, one of the main ingredients of concrete. With concrete being an ideal construction material, and Sweden needing to build more urban housing, Sweden is now in a position where they need to combine a high rate of housing construction with emission cuts to reach the climate goals. Concrete from construction and demolition waste is recyclable and can be used as an aggregate in new concrete and as an input in cement production. This is, however, currently not being done in Sweden and concrete waste is instead used for low-grade purposes such as road construction, landfill infrastructure, and backfilling.  This study, therefore, aims to identify why recycled concrete is not being used to a larger extent in Swedish housing. An interview study has been conducted with actors along the concrete value chain to find out the extent to which housing projects use recycled concrete today, as well as what challenges and possibilities there are for increased use. The results show that recycled concrete within housing projects is currently only used for backfilling. Sweden does not have big enough volumes of high-quality concrete waste for it to be commercially viable to recycle it into recycled aggregate concrete. This recycling process is both costlier and more time-consuming than using conventional methods with raw materials, something Sweden has an abundance and easy access to. There is also a reluctance within the construction industry to use new and unproven methods and materials. Improved on-site sorting of waste materials, leading to higher quality aggregates, and construction standards adapted to the use of recycled materials, are actions to be taken to allow for an increased use of recycled aggregate concrete. All interviewed actors also mentioned the potential of recycled concrete for non-load-bearing walls in housing projects.