Changing the characteristics of cement stone with the calcium stearate additive under the influence of fungal microorganisms

The study of changes in the strength and porosity of cement stone of concrete with a hydrophobic additive during fungal corrosion has been carried out. At the stage of sample production, calcium stearate was added to the cement mixture in an amount of 0.5 and 0.7% by weight of cement. Hydrophobic cement stone has a porosity of 31-36% lower and a strength of 8-12% higher compared to the sample without additive. The calcium stearate additive promotes the formation of more calcium-containing phases in the structure of cement stone. Cement stone with a hydrophobic additive shows high resistance to fungal corrosion. During 12 months of exposure to hydrophobized cement stone of Aspergillus niger fungi, the strength and porosity remained almost unchanged, and in ordinary cement stone under these conditions, porosity increased by 22%, strength decreased by 9.5%. X-ray diffraction analysis of samples after exposure to fungal microorganisms showed that the number of phase components in cement stone with the calcium stearate additive did not change, which explains the preservation of strength characteristics. A significant decrease in all calcium-containing phases was recorded in cement stone without additives, which led to a decrease in strength. By introducing calcium stearate into the cement mixture, it is possible to sufficiently increase the resistance of concrete to biocorrosion.