The effect of microbial and chemical corrosion on concrete structures operated in the conditions of chemical enterprises has been established that makes it possible to reliably predict the timing of their decommissioning in order to prevent industrial disasters. Even though the construction complies with all building codes, concrete structures eventually undergo chemical and biological corrosion. The innovation proposed in this study implies investigating the depth and degree of damage to concrete at the microscopic level by the method of raster electron microscopy. In addition, the TPD-MS method has been suggested for determining the quantitative and qualitative state of the carbonate components of concrete and sulfur compounds. This study has found that in concrete samples from the titanium dioxide production plant, the amount of carbon dioxide release is twice less than in control samples at t=600 °C while the level of sulfur dioxide, on the contrary, increases. This is due to the ability of thionic bacteria to accumulate sulfate acid that destroys the cementing component in concrete. The reported results confirm the impact of products of the activity of Acidithiobacillus thiooxidans microorganisms on corrosion processes in concrete. In addition, when using the TPD-MS method, it was established in the storage room of the finished product that heating the control sample of concrete leads to a release of the significant amount of СО2 at t=580–600 °C. However, the experimental samples of concrete are almost lacking carbon compounds because the acid metabolites of microfungi interfere with its formation. Microscopic and REM studies revealed the localization of Acidithiobacillus thiooxidans and Aspergillus fumigatus in concrete. This study has established patterns related to the mechanism that forms chemical compounds in concrete and the metabolism of microorganisms

This paper reports research into the development of compositions of engobe coatings for ceramic bricks and investigating the influence of technological production factors on their physical and mechanical properties. The results of this work make it possible to solve the task of expanding the range and improving the operational properties of building ceramics. The data obtained have made it possible to establish physicochemical processes occurring during the formation of the phase composition and structure of engobe coatings. This has revealed the possibilities for designing engobe for various types of ceramic bricks, which differ in technological parameters of production and operational properties. The charge compositions were designed in a three-component system "refractory clay – quartz sand – cullet", taking into account the possibility of their practical implementation in large-tonnage production. It has been established that the most important condition for obtaining high-quality products is the correlation of shrinkage and temperature coefficients of linear expansion of the ceramic shard and engobe coating. To prevent various defects, these indicators should vary by no more than 10 %. The crystal-phase composition of engobe is represented by b-quartz and a small amount of devitrite, which are evenly distributed in a vitreous dense layer of coating on the surface of the ceramic shard. Distinctive features of the results relate to the fact that a solution to the problem of designing engobe coatings for ceramic bricks has been proposed and the physicochemical bases of production have been highlighted. This paper also suggests ways to achieve coordination of finely dispersed coatings with coarse-grained ceramic masses by shrinkage and thermal processes. The results reported here could be applied in typical production of face, clinker, and in some cases – ordinary brick or ceramic stone with firing temperatures of 950–1150 °C

Abstract. The research deals with the main directions of the Reinforced Concrete Theory current improvement on the basis of its incisive analysis. As leading direction in solving such a problem, the modern, well known deformational analytic model is examined. It is implemented on the base of complete experimental diagrams of deformation of different structural materials. The offered methods for improvement of such model suggest the creation and use of the transformed diagrams of deformation of concrete, reinforced elements as well as those structural elements on their basis. The modelling of these diagrams is envisaged on the basis of experimental dependences of complete diagrams for deformation of construction materials taking into account the influence on them of different physical, technological, dynamic and other factors. The general view of the said diagram will be realized by two its branches – ascending and descending, designed by different parametric (key) points. The special interest on the modern stage in development of deformational analytic model presents the design of descending branch of complete diagram on the state of construction material that is recorded by different parametric points. One of the main tasks in designing of such points is standardization of experimental methods in determining the critical values of relative power deformations in the top of a diagram, that correspond to the limit straining of construction material, that does not exceed the board of its durability at a compression. The descending branch of complete diagrams must be designed on condition that the deformation of concrete became consistently waning. The transitional point of this state in sustained and increasing deformation it to be considered as destruction start of material at intensively increasing destructive transformations of its structure. The straining of constructional material on such on-loading area of diagram can diminish to the level of postcritical values, beyond the durability range of stability at a compression, and to correspond to relative deformations in the limit state. Further reduction in tension to the concrete is representative at its dynamic deformation in terms of more intensive development of destructive transformations. Thus the level of relative deformations can increase to the maximally possible values, beyond which a concrete, as structural material, stops to comply with the necessary operating qualities. The long-term experience in initiation, perfection and development of theory of the reinforced concrete, as well as implementation of its modern deformational model of calculation show that there is a number of important vital problems which need to be examined and solved for today. Such problems in the outlined aspect are to be examined in two directions of researches. The first is an improvement of methodology of tests and standardization of methods in obtaining the complete experimental diagrams of the state and their parametrical points which allow to design dependence sb – εb (straining – deformation) with high authenticity by the analytical function for its implementation at the calculations of different structural elements; the second is an improvement of deformational calculation model with help of the transformed diagrams of deformation, as well as more precise definition of some pre-conditions and positions accepted in different existent standards for the calculation of concrete and reinforce-concrete constructions. The essence in solving of the above-said pressing issues set forth in this research.

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The article provides a technology for determining the displacement of the end of the reinforcing bar embedded in concrete for measuring the shifting force in the longitudinal reinforcement. Dependences of the displacement of the end of the reinforcing bar on different protective layers are shown. A formula to define the displacement of steel reinforcing bars due to the shifting force is given. The formula was obtained by the numerical computation approximation using three-dimensional finite elements. A method for determining the torsional stiffness of reinforced concrete element with normal crack is presented. In this method the pliability of the reinforcement perpendicular to its axis is also considered.