The effect of calcium stearate on the microbiological corrosion of cement stone concrete

Abstract

To prevent biofouling of cement stone and its damage by fungal microorganisms, it is proposed to introduce 0,5 wt. % calcium stearate into the cement mixture. To ensure volumetric hydrophobization of cement stone, the additive is crushed to nanoparticles. The cement stone was cured in the air for 28 days. To study fungal corrosion, the surface of the cement stone was treated with a suspension of pores of Aspergillus niger fungi. The hydrophobic surface of the cement stone was not biofouled by fungal microorganisms Aspergillus niger during 6 months of the samples being in a humid environment, and black mold foci developed on the surface of ordinary cement stone during this period of time. The action of fungi and their waste products caused a decrease in the amount of calcium in the cement stone by 9 %, and had no effect on the hydrophobized cement stone. Due to the immunity of cement stone with a hydrophobizer to the action of microorganisms and water, free calcium hydroxide is not removed from the structure, but some amount is washed out of the surface layer and the pore liquid. A significant slowdown in mass transfer in cement stone under the action of liquids is provided by the hydrophobicity of the surface of cement stone and the walls of pores and capillaries, imparted by calcium stearate, as well as partial colmatation of the pore structure by means of the introduced additive.