Recycling concrete in practice – a chance for sustainable resource management

Private households consume about 30 % of Germany's total primary energy and cause about 15 % of the total CO2 emissions, and so this sector represents a key sector for climate protection targets. Whereas primary energy consumption in buildings is limited by regulations, the production of carbon emissions-intensive materials is only moving slowly into the focus of legislation, regulations and, ultimately, the perception of society. Considering a thermally conditioned building during its life cycle, most environmental effects are during operation. Nevertheless, the grey energy of a concrete structure can add up to 20 % in individual cases. Owing to the carbon-intensive cement production, concrete as a material causes relatively high environmental impacts. Logical options appear to be substituting cement with so called by-products or using recycled additives. In fact, there are only a few projects that have used a resource-saving concrete. In 2010 in Ludwigshafen, one building in a group of buildings was chosen as the first building in Germany to be built almost completely from recycled concrete without increasing the cement content. It was built as a low-energy construction and in a zero-carbon-emissions area. The project was supported scientifically by the Institute of Energy and Environmental Research in Heidelberg and the Brandenburg University of Technology Cottbus. The buildings won the Construction Prize 2011 with the distinction “best relation between quality and costs”. This paper discusses integral aspects of the use of recycling concrete from the structural design, eco-accounting and materials properties perspectives. It demonstrates the potential and opportunities for the quality-assured use of recycling concrete for sustainable resource management.