Potentials for a circular economy of mineral construction materials and demolition waste in urban areas: a case study from Vienna

Mineral construction and demolition wastes (CDW) are generated when buildings and infrastructures are renovated and when they reach their end of life. As one of the largest waste streams, they have a considerable potential for the reduction of waste generation, landfilling, and primary raw material consumption. To make use of this potential, sustainable development strategies of many cities include a circular management of CDW by measures in line with the waste hierarchy. The present study uses material flow analysis to determine how waste reduction, re-use and recycling of mineral CDW generated in a city can contribute to reduce the demand of raw material imports for construction minerals, using the case study of the city of Vienna. The results show that the annual consumption of construction minerals of 4.5 million tons can be reduced by 32% to 3 million tons by implementing the waste hierarchy to CDW. The most important measures are the use of recycling materials from mineral construction and demolition waste as recycling aggregate in concrete (575,000 t/yr), followed by the use of recycling material to substitute gravel in unbound form (463,000 t/yr), avoiding the demolition of historical buildings by extending their service life (230,000 t/yr), asphalt recycling (85,000 t/yr), and substitution of raw-mix in cement by recycling material from debris (84,000 t/yr). Re-use of full bricks (17,000 t/yr) is of lesser relevance. To implement this enhanced circularity scenario, however, efforts in installed technology, construction and demolition waste management as well as legal and entrepreneurial measures are required.