Investigation of concrete properties of reinforced concrete constructions of structures operated in the coastal zone of the Black Sea coast
Concrete and reinforced concrete are used for the erection of buildings and structures with long service lives. The use of structures from these building materials is of a massive nature, to meet the need for construction in the world, more than 4,5 billion m<sup>3</sup> per year of concrete and reinforced concrete are produced. In the course of operation, structures are often exposed to unfavorable environmental influences (aggressive chemicals in the form of gases, solutions of salts and their aerosols, microorganisms) and find themselves in difficult working conditions. These effects contribute to the destruction of materials and reduce the durability of structures, which in some cases can fail in a year or even months after the start of operation. With the location of construction sites near industrial plants and on the sea coast, the impact of unfavorable factors may increase. The article presents the results of an investigation of the content of inorganic salts and species composition of microorganisms in the surface layer of concrete reinforced concrete structures operated on the Black Sea coast. The authors presented the results of a study of concrete samples taken from pier structures directly in contact with seawater, depending on elevation marks relative to sea level and orientation to the sides of the world. Also, the results of the study of samples taken from fence designs located at a distance of about 50 m from the coastal edge are obtained, depending on the orientation of the fence along the sides of the light and its parallel or perpendicular position relative to the shore line. A correlation was found between the levels of salt content and the species of microorganisms inhabiting the surface layer of concrete in coastal structures. It is established that under the influence of the sea climate, a high temperature of air, solar radiation, wind, biological environment, moisture and impurities of hygroscopic sea salts in the air occur simultaneously on the building structures. The intensity of the impact of negative factors depends on the elevation marks of the location of structures relative to the level of the smooth surface of the water and their orientation relative to the shore and to the sides of the world.