Sand-lime bricks are manufactured from the raw materials lime, natural mineral aggregates and water. Apart from the rare use of inorganic color pigments for coloring sand-lime bricks, no additives are used. Quartz sands or also crushed natural stone material are mostly 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.

Highly fine amorphous SiO2 and temperature-resistant CSH nuclei are to be added to the raw lime sand mass in defined doses, both individually and in combination, and their effect on the quality-characterizing property values of lime sand bricks is to be investigated.