Sand-lime bricks are a traditional mineral building material. They are made from the natural raw materials lime, natural mineral aggregates and water. Apart from the extremely rare use of inorganic color pigments for coloring sand-lime bricks, no additives are used. Quartz sands or crushed natural stone material, such as basalt, diabase and graywacke, are usually used as aggregates. The raw materials are mechanically compacted in the earth-moist state and then hardened in autoclaves under pressurized steam. Essentially, during this hydrothermal hardening, reactions take place between the hydrated lime and the dissolved silica in the pore space of the sand-lime bricks. Permanent calcium silicate hydrates (CSH phases) are formed, which give the structure of the sand-lime bricks their strength. The duration of steam curing is usually th = 6 to 12 hours and takes place at temperatures around th = 200 °C and an associated water vapor pressure of up to pe = 16 bar. Since the stone bulk density is largely responsible for the stone strength and other positive properties such as its sound insulation, this research project attempts to increase the compactability of the stone bulk or minimize the energy required for compaction by optimizing the microstructure and using other techniques known from UHPC production. At the same time, the minimum porosity necessary for the hardening of the stone is to be maintained, without the effect of which the stone blanks cannot harden during water vapor transport.