In the processing of construction and demolition waste - the largest waste stream in Germany - only 1% of the mineral waste is currently reused in high-quality applications such as building construction. Almost all of this waste is used only in lower-quality applications. In a research project possibilities are investigated for processing mineral construction waste using hydrothermal curing with the aim of reusing it in high-value applications. Hydrothermal treatment improves the strength of the material, which can then be used e. g. as a (light) aggregate for concrete, or as filling material. Some results of the current research project are presented.