Using the appropriate secondary raw materials, it is possible to reduce the bulk density of AAC while preservation the physical-mechanical properties, e.g. strength. This reduces the total weight of the construction and allows for wider use, for example, in the application of material to reduce the load on non-load-bearing walls or to increase floor levels. Research is focused on the use of 10%, 30% and 50% admixture of fluidized bed combustion ashes and slag in the AAC. AAC was developed in the hydrothermal conditions of the autoclave at 7 hours of isothermal soak at 190 °C. The results showed the dependence of the rheological properties on the amount of admixture of fluidized bed combustion fly and bottom ash, slag. Research has shown that the use of 10% admixture of secondary raw materials will not significantly affect the physical properties of the samples.