Today, the development and research of new designs requires a systematic approach, including design, manufacture of products and construction. Further development of construction follows the path of improving the designs and forms of buildings, which is facilitated by the improvement of the physical and mechanical properties of building materials. The use of high-strength concrete and steel leads to the creation of lighter thin-walled reinforced concrete structures and is fundamentally possible only with perfect technology for the manufacture of elements. Since in the manufacture of reinforced concrete products by a centrifugal method, radially directed filtration channels are formed, it is in them that the manifestation of destruction is most likely. It is aggravated by the fact that the inner layer of such products is more porous than other layers of concrete. The presence of such a structure is determined even if all the requirements for the quality of the raw materials, the preparation of the concrete mix and the use of optimal centrifugation modes are met. The authors in the process of confirming the working hypothesis in this study developed a method of introducing aggregate during centrifugation, on the basis of which prototypes were obtained, which are characterized, compared with the control, improved physicomechanical and structural properties; an increase in the carrying capacity of centrifuged reinforced concrete columns of annular cross section was achieved at the stage of their manufacture by changing the nature of the manufacturing process from one stage to two stages. Testing the hypothesis was carried out by the determined increments of the structural and physical characteristics of the concrete samples. The density of concrete prototypes of centrifuged reinforced concrete columns of annular section of two-stage molding with all three ratios of fractions was higher than that of single-stage concrete. Water absorption at concrete capillary suction of prototypes of centrifuged reinforced concrete columns of annular section of two-stage molding with all three fractions ratios was lower than that of single-stage concrete.

Keywords: centrifuged concrete, reinforced concrete columns, aggregate fractions, two-stage technology, annular section, density, water absorption, structural and physical properties

Presented and theoretically justified ways of improving the technology of centrifugation, to increase the uniformity of the concrete structure in the cross section, for example, by way of separate introduction of the components of concrete, the essence of which in the manufacture of spun goods consists in the introduction into the molding unit prior to the stage of compaction of coarse aggregate. The results of physical and mechanical tests of centrifuged concrete, showing that the layer-by-layer introduction of the concrete mixture components by the first method leads to an increase in the compressive strength in all layers of centrifuged concrete

Keywords: concrete, centrifugation, uniformity of structure, layer-by-layer introduction of components, compaction, water absorption at capillary suction, strength

The analysis of the experimental data is carried out and the works devoted to the account of the influence of the compressive pressure factor with the purpose of optimizing the parameters of the centrifuged products of the annular section at the compaction stage are studied. The number of rotations of the mold at the compaction stage is calculated for different values of the compressive pressure. A statistical analysis of the regression equations obtained is performed using three criteria: homogeneity of variances, significance of coefficients and adequacy, which was tested with the help of Fisher's criterion. The data were statistically processed using the Mathcad program, which allowed obtaining regression equations in the form of polynomials of the second degree with specific values of their coefficients. Graphic interpretation of mathematical dependencies is constructed. The calculated dependencies are obtained that allow to determine the required number of revolutions for any required diameter and wall thickness of annular centrifuged products for a given fixed value of the compressive pressure in concrete.

Keywords: compressive pressure, centrifuged products of annular section, response function, factor of variation, least squares method, regression equation

A review of the literature concerning the molding of centrifuged concrete products was carried out. The peculiarities of centrifugation of concrete, in particular, the manufacture of centrifuged pipes, have been studied. The main parameters and indices of the quality of concrete and the centrifuged tubes themselves are considered. The traditional mode of forming non-pressure pipes is described. The calculation formulas for the parameters of the centrifugation process and their graphical dependences are given. Based on the calculated data, it is concluded that the traditional modes of shaping of non-pressure pipes are characterized by the rotation speed of the mold from 82 to 300 rpm in the stages of loading and distribution of the concrete mixture. At the sealing stage, the control of the rotation speed of the mold varies over a very wide range and depends largely on the viscosity of the concrete mix and the pressing pressure: from 825 to 4400 rpm for concrete pipes with a diameter of 100 to 300 mm. Modeling the parameters of the molding regime during the centrifugation of ring-shaped products in a laboratory installation at a maximum compaction pressure of p = 2.16 kg/cm2 will allow us to refine the obtained data and study their effect on the variability of the concrete structure

Keywords: centrifugal force, centrifugation parameters, charging speed of the mold, speed distribution of the shape, sealing speed of the mold, pressing pressure, centrifugation time, ring-shaped products

"n this article, the influence of the physical state of chemical additives at the moment of their introduction into a gas-concrete mixture on the kinetics of gas evolution and the gas diffusion coefficient is considered. To test the working hypothesis, two compounds were designed and manufactured. As a part of С№1 chemical additives were entered in the form of a colloidal solution. A comparative analysis of the results of physical and mechanical tests of the aerated concrete samples of the tested compositions showed that the introduction of chemical additives in the form of a colloidal solution lowers the average density in the dry state due to a more intensive course of the gas evolution reaction without significantly reducing the compressive strength. At the same time, the average density increases in the composition of CN2.

Keywords: kinetics of gas evolution, gas diffusion coefficient, aerated concrete mixture, reactivity, expansion of aerated concrete mixture, colloidal solution

This article considers the effect of the introduction of a partially hydrated aerated concrete mixture on the intensity of gas evolution, the reactivity of a disperse gas generator, and the physical and mechanical properties of aerated concrete. To test the working hypothesis, two compounds were designed and manufactured. The pure dispersed gas generator was introduced into composition C№1, and a mixture of a gas generator with a partially hydrated gas-concrete mixture was introduced into the composition C№2. A comparative analysis of the results of physical and mechanical tests of the aerated concrete samples of the tested compositions showed that its introduction increases the compressive strength, while reducing the density of aerated concrete. At the same time in the composition of С№1 there is a higher density and a drop in strength

Keywords: Partially hydrated mixture, gas generator, aluminum powder PAP-1, reactivity, device PGV-2, kinetics of gas evolution, average density in the dry state, compressive strength

The composition of non-autoclaved aerated concrete with blast-furnace granular slag was developed and optimized, which was introduced in an amount from 5 to 15% instead of a part of the silica component (quartz sand) into aerated concrete. By the results of optimization by the method of least squares, the basic regression equations were obtained in the form of polynomials of the second degree and the optimal compositions of non-autoclaved cellular concrete with the addition of blast-furnace granular slag. In this case, the most effective is a dosage of 15%, which has a positive effect on the increase in strength of cellular concrete in comparison with the control composition and does not lead to an increase in the average density.

Keywords: non-autoclaved aerated concrete, active mineral additive, medium density in the dry state, compressive strength, blast-furnace granular slag, least-squares method, regression equation, silica component

The methods of directed formation of the variational structure of concrete products and structures are considered in the article. The experience of Russian scientists in the issues of obtaining articles of different density over the section has been studied. The problems of the technology of obtaining articles of different density along the section are considered, the main principles of shaping the variational pore structure of aerated concrete for monolithic enclosing structures, the optimal schemes for forming two-layer wall products from concrete of various densities, forming a structure with a double skeleton - mineral and polymeric - by sintering the polystyrene grains, the formation of variational structure of magnesian foam concrete, which involves sequential laying of foam masses with various average, perspectivity of the use of reinforced concrete constructions of a variational structure.

Keywords: Variational structure, concrete products and structures, reinforced concrete, aerated concrete, foam concrete, expanded clay concrete, density, fire resistance

In the article the problems of the technology of aerated concrete products of non-autoclaved hardening are considered and the literature data concerning the study of the influence of various factors on manufacturing technology are analyzed. The results of experimental studies devoted to the study of the role of additives of various types in the formation of aerocrete structure are presented. The influence of three factors was investigated: the type of surfactant introduced into the aerated concrete mix; presence of caustic soda additive; the consumption of aluminum powder on the process of structure formation and the properties of non-autoclaved aerated concrete. The obtained data made it possible to take a detergent powder as a surfactant in further experiments. It has been experimentally confirmed that exclusion of caustic soda from the composition of the aerated concrete mix leads to a decrease in alkalinity, and accordingly the gas release reaction proceeds much more slowly, which leads to an increase in the density of aerated concrete, the appearance of defects on the surface of products, and a significant increase in rejects. The optimal content of aluminum powder in the composition of aerated concrete is determined, which corresponds to grade PAP-1 - 5.75 g.

Keywords: Non-autoclaved aerated concrete, additive, surfactant, caustic soda, aluminum powder, gasifier, gassing

This article considers the influence of a structuring additive on the physical and mechanical properties of aerated concrete. As a structuring additive, a by-product was introduced into the composition of the aerated concrete mixture by cutting the top layer of the "gorbuschka" in an amount of 10 to 30%. Comparative analysis of the results of physical and mechanical tests of aerated concrete samples with different amount of structuring additive showed that its introduction increases the compressive strength, while simultaneously increasing the density of aerated concrete. At the same time, the value of the constructive quality factor in GB4 (with 20% of the "gorbuschka") is 20.4% higher than in GB2 (with 30% of the "gorbuschka") and 31% higher than for the aerated concrete base composition GB1 (control) that allowed us to take him for the optimal composition in further research.

Keywords: "gorbuschka", structuring of aerated concrete, non-autoclaved aerated concrete, structuring additive, swelling process, plastic strength of the structure, constructive quality coefficient, average density in the dry state, compressive strength