Due to the complex and constantly changing global environmental situation, the study of the resistance of mineral binder-based building composites to the effect of the metabolism products of microscopic organisms seems particularly relevant. Taking into account the nature of the effect of bacteria and mycelial fungi on cement stone, a method of evaluating the resistance on the basis of modeling by replacing the real development of colonies of microorganisms with chemically aggressive aqueous solutions of their life products is proposed. It is allowed to study the current processes of phase transformations, as well as changes of operational parameters in the form of regression dependencies.