Protection of buildings and structures made of stone materials from biological corrosion is relevant for all groups of buildings, especially in wet and wet modes of operation of external enclosing structures and in conditions of pollution from industrial emissions. The presence of salts in raw materials, mixing water and technological additives to improve the properties of the mixture in the manufacture of building materials, masonry and plaster mortars causes the transfer of salts to the facades of buildings. Due to the hygroscopic effect, salts attract atmospheric moisture, and waterlogged material is a favorable environment for the development of spores of various types of filamentous fungi. The combined effect of salt and biological corrosion reduces the strength properties of materials. Destruction of paint and plaster layers disrupts the appearance of building facades. The study investigated the biological resistance of samples of facade plastering systems to the action of test cultures of filamentous fungi. The fungicidal and fungicidal properties of facade plastering systems of various compositions have been studied. The influence of different types of primer, filler and color on fungal resistance, fungicide and physical and mechanical properties of facade coatings was revealed. It was revealed that multilayer facade systems, consisting of materials with high vapor permeability, water-repellent properties and biostability, provide joint protection against salt exposure and the influence of biological pollution. The aesthetic qualities of the facade surface are ensured by decorative plastering or painting.
Energy saving in buildings is largely determined by the energy efficiency of the external building envelopes. The latter, as a rule, are the multilayer and incorporate structural and heat-insulating layers. The presence of individual hygroscopic salts and their mixtures in building materials changes their physical and chemical properties. Due to the increase in the sorption properties of building materials and changes in the inter-pore substance composition, humidity increases and the heat-protective properties decrease. This paper presents the results of the experimental and theoretical studies on the salts’ effect assessment on the change in moisture content and thermal conductivity of building materials due to the salt solutions and crystals’ presence in the pore space. To study the saline building materials’ thermal conductivity, the mathematical modeling methods using the theory of flow and bringing the materials’ structure to a unit cell are used. It is shown that the change in thermal conductivity occurs due to the crystalline salt precipitation from the solutions in the material’s pores, to the changes in their initial chemical properties, to the changes in the properties of the vapor-air mixture above the salt solutions due to diffusion. The results obtained make it possible to establish the hygroscopic salts’ influence significance in solid and liquid phases on the building materials’ thermal conductivity. A scheme for determining the thermal conductivity of building materials is proposed, taking into account salt effects, including the determination of: the components’ volume concentrations; sequentially the thermal conductivity of the material’s shell; salt crystals, a solid phase consisting of the material’s shell and crystalline salt, a binary and multicomponent saline solution, the pore space and the pore substance inside. The general formula for determining the thermal conductivity of a saline building material is given.
The structure of filled cementitious composite materials is formed as a result of hardening with the formation of a crystalline framework. The filler is involved in the building material crystal system structure formation. Chemically active fillers promote intensive release of hydration products that bind into insoluble compounds and increase the system stability. When developing the formulations for dry building mixtures, it is effective to use several fillers with different properties that complement each other, and biocidal additives increasing the materials resistance to environment effects formed by mold fungi. To create modified dry building mixtures based on cement binder, materials such as filler made of quartz sand of various fractions, fillers chrysotile and clinoptilolite and biocidal additives of the Teflex series were used. The composition with sand grains of 0.16–0.315 mm in size showed high strength properties in bending and compression. The introduction of chrysotile in an amount of 3% by weight of cement and quartz sand with a particle size of 0.16–0.315 mm increases the compressive and flexural strength by 7 and 13%, respectively, compared with the control composition. Clinoptilolite, introduced in an amount of 20% of the cement mass instead of one of the quartz sand fractions, increases the compressive strength of the composites up to 5%. The introduction of the Teflex series additives in the amount of at least 1% by weight of the binder ensures the composites’ fungal resistance. The additive “Teflex disinfectant” in an amount of at least 3% of the cement mass gives the composites fungicidal properties, the zone of no fungal growth on the nutrient solution near the infected samples is 4 mm.
Investigation of concrete properties of reinforced concrete constructions of structures operated in the coastal zone of the Black Sea coast. Russian journal of transport engineering, [online] 2(5).
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