The article is devoted to the determination of the patterns of the formation of the microstructure of foam concrete using Portland cement, opoka marl and fly ash. Binder composites obtained by joint grinding of these were prepared in the form of new compounds, on the basis of which concrete with improved mechanical properties and performance characteristics are created. The complex of experimental studies included studies of the thermal intensity of hydration, shrinkage, average density and compressive strength. A number of operational characteristics were also comprehensively investigated: frost resistance, thermal conductivity and vapor permeability. Both microstructural and morphological studies of the developed composites were investigated using the analysis of SEM images, X-ray diffraction patterns and DTA patterns. The experimental results of composite binders and foam concrete based on it are presented. The mechanism of the influence of fly ash on the formation of the microstructure of the foam concrete mixture for building envelopes is determined. Binder composites obtained by co-grinding the components have a compressive strength of up to 60 MPa with Portland cement savings of up to 40 %. Based on the binder composites, foam concrete with a density of 500–700 kg/m3 and compressive strength above 4 MPa was obtained. In addition, a technological scheme was developed for the production of non-autoclaved foam concrete for the manufacture of blocks, as well as for monolithic construction.