Microbiological corrosion of building materials

Abstract

The research results in the field of microbiological corrosion of building materials of domestic and foreign experts are presented. It is shown that microorganisms cause corrosion of concrete on cement and other binding metal and other materials. Metals in the order of decreasing the rate of biocorrosion are arranged in the following row: aluminum, mild steel, zinc, brass, copper, stainless steel. Concrete, due to its high surface activity, is capable of adsorbing a wide variety of substances, including microorganisms: bacteria and mycelial fungi. Among bacteria, nitrifying agents, thionic, iron and silicate bacteria and others participate in the corrosion of cement concrete (mainly due to their acid secretions). According to the data of a number of authors, on the surface of stone building materials mycelial fungi of the genera Penicillium, Aspergillus, Trichoderma, Cephalosporium prevail. Biodeterioration in this case mainly comes down to the disruption of cohesion of constituent components as a result of exposure to mineral or organic acids, as well as enzymes and due to chemical reactions between the cement stone of solutions and concretes and the waste products of microorganisms. The compositions of bituminous composites at various ratios of the materials used without inclusion in the composition of fungicides showed non-fungal resistance and non-fungicide. Comparison of concrete on gypsum and phosphogypsum binders showed that samples on a phosphogypsum binder overgrow microorganisms somewhat more, wood materials are subject to significant biodeterioration at high humidity. Biodegradation of wood occurs mainly due to the use of mushrooms as food sources of cellulose, lignin and other components. Synthetic polymers and materials based on them are significantly superior to natural polymers in biostability. However, under certain operating conditions, they are damaged by biological agents. Biological damage to plastics, as well as other materials, occurs simultaneously with their aging under the influence of external physical and chemical factors (ultraviolet radiation, water, temperature changes, etc.). Additives that are usually always present in polymer compositions (fillers, plasticizers, stabilizers, antioxidants, modifiers, pigments, etc.) significantly affect the biostability of polymeric materials. One of the effective ways to increase the biostability of composite building materials is the introduction of fungicidal additives in their composition. It is also shown that of great importance in increasing the durability and increasing the life of some building structures (metal products, communications, underground pipelines and some others) is their protection by paint and varnish coatings.