In this project, in cooperation with the Forschungsvereinigung Kalk-Sand e.V. and the Forschungsgemeinschaft Kalk und Mörtel e.V., the potential of replacing the usual aggregate in sand-lime bricks is being researched in order to reduce the CO₂ emissions of the finished building material. According to the standard, other, silicon-rich aggregates than the conventional "sand" may also be used, as long as their suitability is proven. Accordingly, new aggregates are used that have a high proportion of natural minerals that can bind CO₂ during the use phase. This means that in addition to the binder matrix (C-S-H phases), the aggregate should also absorb CO₂ in order to reduce the environmental footprint of the building material.