The article is devoted to the effect of internal hydrophobization of concrete cement stone on the kinetics of damage by Aspergillus niger fungi. The studies were carried out on samples made of ordinary Portland cement with a W/C = 0,3. As a hydrophobic agent, 0,5 and 1% by weight of cement of calcium stearate were introduced into the cement mixture. The kinetics of calcium leaching from cement stone was evaluated by changes in the calcium content in the liquid when samples were exposed to water. Internal hydrophobization of cement stone with calcium stearate makes it possible to reduce the removal of calcium from the solid phase by 2,5-3 times, even with biofouling of the surface. The equilibrium state in the «cement stone – water» system occurs 70 days after the samples are immersed in a liquid medium. The profiles of calcium concentrations along the thickness of the cement stone characterize a decrease in mass transfer in samples with hydrophobic additives. The introduction of calcium stearate into the cement mixture increases the total calcium content in the structure and reduces calcium leaching as a result of liquid and fungal corrosion. Volumetric hydrophobization of cement stone leads to a decrease in the values of mass conductivity coefficients by two orders of magnitude, from 10-9 to 10-11 m2/s. Using a mathematical model of concrete biocorrosion, the degree of destruction under the influence of fungal microorganisms and water is predicted after 15 years. During this period, corrosion processes will occur in ordinary concrete throughout its entire thickness, in hydrophobic concrete – only in the surface layer. With calcium stearate additives to concrete, it is possible to extend the maintenance-free service life under conditions of exposure to fungi and moisture for up to 30 years.