Turning concrete waste into a resource by applying the principles of circular economy

Construction and demolition wastes (C&DW) are considered a major waste issue within the European Union (EU), representing a third of all the waste generated in Europe, or approximately 800 million tons per year. Concrete waste represents one third of the C&DW. In line with EU ambitions to move towards a more sustainable economy, extending product life-time, reuse, recycling and other ways for material recovery are strongly encouraged. Experts from both academia and businesses suggest applying the notion of circular economy (CE) is a way to underline the large environmental and economic benefits that reuse and recycling of concrete could actually bring to the industry. However, reuse and recycling rates of concrete vary significantly within the EU, with an average rate of between 30%-60%. In Denmark, almost all end-of-life concrete is considered waste and used either as road sub-base or as other lower value applications. There is still a large untapped potential for alternative applications of recovered concrete linking to the inner CE loops. Some examples are recycling crushed concrete as aggregate for new concrete or even reusing complete concrete elements in new buildings. Yet, such practices are currently not common in Denmark. This study will use different initiatives and cases in Denmark and analyse the main factors influencing decision-making in span from extending lifetime of concrete structures over reuse and reconditioning of different concrete elements to different options for recycling concrete. Semi-structured interviews with concrete producers, construction companies, authorities, waste handling companies and relevant research institutes will indicate the existing practices and improvement potentials. A more systematic approach for the construction industry will be proposed when selecting a strategy for handling concrete, highlighting the economic, environmental and social factors that should be considered during decision-making. The principles of CE will be favoured as part of an overall strategy for moving concrete waste further steps up in the waste hierarchy. The outcomes of this study are expected to feed new insights on the relevance of rethinking current practices of handling products at their end-of-life, as well as suggest ways to design and implement CE principles in the context of construction materials and buildings.