Carbonate crusts on facades of buildings of Tyumen: occurrence and diversity
Relevance. Carbonate crusts, outgrowths and efflorescences, formed on the facades of various buildings and structures due to components leaching from building materials, such as cement, concrete, limestone, are the most common type of technogenic mineral formation in urban environment. Unlike the unstable stalactites and stalagmites, which are formed only under certain conditions, and the period of existence, as a rule, is limited, such formations are widespread. Development of carbonate crusts, outgrowths and efflorescences on the facades of buildings not only indicates destruction of the bonding components of building structures, but also has a negative impact on aesthetic appeal of urban architecture. Rigid calcite formations fill microcracks and surface irregularities of facing materials, such as granite, which leads to intensification of destruction of natural materials and reguires expensive cleaning of facades. Despite the obvious urgency of the problem, there are not many studies devoted to carbonate neoplasms on various buildings and structures. The main aim of the research is to investigate the peculiarities of mineral composition, structure and possible mechanisms for formation of carbonate cores and filaments generated on the facades of buildings and structures of the city of Tyumen under various conditions, and to identify the factors contributing to this phenomenon. The methods: identification and systematization of objects of urban architecture subject to formation of carbonate, crusts, outgrowths and efflorescence; study of structural features of the most representative samples of carbonate neoplasms in transparent sections, using scanning electron microscope; determination of gross mineral composition of tumors (X-ray analysis). The results. The carried out research shown that carbonate cortices and sinters essentially differ in features of structure, mineral structure and probable mechanisms of formation depending on a concrete site. The crusts developing on vertical and horizontal surfaces are clearly divided: the first are flat, thin enough and have a layered structure, the latter are dense and are characterized by a globular structure. Development of carbonate formations probably occurs with significant participation of living organisms. Biogenic and chemogenic processes of calcite precipitation occur synchronically. There are no relationships between the age or location of the studied objects and the intensity of these processes; that is why the constructional particular qualities of buildings and construction materials are the most significant factors.