Soil improvement with construction residues

When rain fails for weeks in summer, urban green spaces suffer particularly. This is because urban trees are often enclosed by sealed surfaces and lawns are particularly stressed by city dwellers. A lack of water thus has an earlier impact. To maintain this greenery, municipalities often have to water such areas regularly.

The GranuGruen project now aims to develop a granulate for soil improvement. The material is intended to store additional water and thus make the soil more climate-sensitive. The plant granules are to be made from construction materials. For this purpose, inorganic and organic materials are mixed and a defined pore structure is created by burning out the latter, which promises a high water storage capacity and regulated water release. The granulate is to be produced from material extracted in the city. This will create an urban circular economy.

Human and phytotoxicity of the granules will be ruled out via planting trials. Further functionalization of the granulate is achieved by loading it with nutrients and inoculating microorganisms. Appropriate production and processing systems are to be developed for decentralized granulate production and the maintenance of surfaces with the product. The new technology will be used in parks, street and facade greening and raised beds, but also in urban gardening areas.


01.05.2022 - 30.04.2025


Federal Office for Agriculture and Food (BLE)




Lina Krenz (M.Sc. Technischer Umweltschutz)


IAB-Institut für Angewandte Bauforschung Weimar gemeinnützige GmbH, Institut für Lebensmittel- und Umweltforschung e.V., IBU-tec advanced materials AG, Christoffers Kulturbau GmbH