Feasibility of substitute building materials for circular use in urban green infrastructure

Mineral waste, including non-hazardous construction waste, is the largest waste stream once a country has reached a certain degree of urbanization. This waste stream has a significant potential to replace primary raw materials. Although a large part of the construction waste is reused, other mineral materials such as ashes or slags have only been used for backfilling or are deposited in landfills. The aim of the investigations is to determine the usability of substitute building materials (SBM) in higher-quality applications, particularly in urban green infrastructure, for example, Reinforced Soil Structures (RSS) or Green Roofs (GR). In addition to technical and environmental requirements, the greening of the material is relevant. The study concept includes soil mechanical laboratory tests as well as greening tests on SBM, namely slags, ashes, residue sands, and crushed/milled brick. The lab results illustrate the feasibility and applicability conditions for the investigated SBM. Upscaling the lab test results, in the next step the construction of a RSS with complete substitution of the primary building materials is started as large scale pilot test.