BauCycle

Four Fraunhofer institutes have joined their competences in order to realize innovative solutions for the reuse of fine-grained building demolition waste, with the aim of recovering valuable constituents of concrete (e.g. raw materials such as sand or gravel) and reusing them in production. For this purpose, the project “BauCycle” was established. In the scope of this project, the researchers deal with the entire product value chain – including innovative optical sorting systems, logistics networks and the development of high-quality building materials. Re-using materials recovered from demolished buildings will sustainably preserve primary raw materials and counter any shortages in landfill sites.

The Fraunhofer Institutes for Building Physics IBP, for Material Flow and Logistics IML, for Optronics, System Technologies and Image Exploitation IOSB and for Environmental, Safety and Energy Technology UMSICHT are developing a novel opto-pneumatic sorting technique for fine fractions, which allows detecting chemical differences in particles in addition to color recognition and brightness detection. In this way it is possible to consider and sort demolition waste according to “construction-relevant” criteria, e.g. “sulfur-based” or “silica-based”. An optimum sorting result ensures the selective separation of gypsum particles from construction waste. The gypsum content is a key criterion for the recyclability of the concrete fraction.

Regarding the fractions separated by the sorting process, various approaches for manufacturing building components are being developed. The aim is to describe potential methods for recycling and use and to demonstrate the technical and commercial feasibility. Besides using the recyclate as raw material for cement production, the manufacturing of granulate materials for use in acoustically effective components is intended. Such building components absorb sound due to their micro- and macro structures, which is why they are used in noise control applications. The future market for recycling materials and building components is promising: porous mineral panels, for instance, are suitable for use in sound absorbers in noise barriers and sound-insulating components. In 2013, about 117,000 square meters of noise barriers were established along roads; around 62 kilometers were built alongside railway tracks. In addition, the scientists focus on developing cement-free binders to provide an alternative to conventional building materials.

As the product value chains derived from the “BauCycle” processes clearly differ from the models previously established in the construction sector, a dynamic market platform is being developed which will accompany the process. Similar to a commodity exchange, which records the supply offered by recycling companies and the demand of companies processing recycling materials, this platform will support the market launch of the products. In this way, “BauCycle” combines the three business units “product development”, “sorting technology” and “marketing”.