Sand-lime bricks are artificial masonry bricks manufactured from the raw materials quicklime, natural mineral aggregates and water in accordance with DIN EN 771-2 in conjunction with DIN 20000-402. With the exception of inorganic colored pigments, no additives other than the above-mentioned raw materials are used. Quartz sands and/or selected natural stone material, such as basalt, diabase and graywacke chippings, as well as single-grade sand-lime brick recycling material (KS-RC) with a particle size range of 0/5 mm will be used as aggregates.

The research project applied for forms a basis for the use of fillers in sand-lime brick production. Following the example of concrete technology, the addition of fillers (< 0.063 mm) is intended to widen the particle size distribution of the aggregate, improve the packing density and thus increase the raw brick density and the brick compressive strength at low cost. As a result, the necessary and cost-intensive binder requirement can be reduced and, consequently, the environmentally relevant emissions generated during production are also lowered.

The implementation of the research results in the manufacturing process would help in particular the SME limestone plants located in the river valleys and in the North German Plain to optimize this process. The wet mining traditionally practiced there for extracting the aggregate washes out fine particles. These could be replaced by adapted filler addition. The use of fillers thus promises not only significant technical optimization potential but also high cost savings. In this project, the specific effects of different fillers on sand-lime brick quality and the associated process engineering adjustments are being systematically researched for the first time.