The current state of the issue of the nomenclature of centrifuged thin-walled prefabricated reinforced concrete products of the ring configuration is analyzed. The scientific interest, which is represented by the technology of fiber reinforcement for such concretes, is grounded. The actual problems for concretes produced by the centrifugation method are indicated. A series of large-scale experimental studies has been carried out to establish the nature of the change in the properties of heavy concrete manufactured by various methods, depending on the reinforcement by different types of dispersed fibers. To systematize the accumulated experimental data, at the first stage of the investigation, products of low-strength concrete, class B20, manufactured by vibration and centrifugation, were molded and investigated, followed by a reduction to uniformity. The compressive strength and tensile strength, as well as their increments, depending on the type of reinforcing fiber-polypropylene, basalt or steel fiber, were studied. The effect on the properties of the investigated concrete of the B20 class is determined by the combination of various prescription and technological factors.

Keywords: centrifuged concrete, vibrated concrete, thin-walled reinforced concrete products, fiber reinforcement, polypropylene fiber, basalt fiber, steel fiber, compressive strength, tensile strength

The scientific interest, which is represented by research for concretes differing in strength characteristics, is substantiated. A series of large-scale experimental studies has been carried out to establish the nature of the change in the properties of heavy concrete manufactured by various methods, depending on the reinforcement by different types of dispersed fibers. At this stage of the study, in order to systematize the accumulated experimental data, the authors molded and examined products made of concrete of class B35, manufactured by vibration and centrifugation, with subsequent reduction to uniformity for the convenience of an analytical comparison of the results obtained. The compressive strength and tensile strength, as well as their increments, depending on the type of reinforcing fiber-polypropylene, basalt or steel fiber, were studied. The influence on the properties of the investigated concrete of class B35 on the combination of various prescription and technological factors has been established.

Keywords: centrifuged concrete, vibrated concrete, thin-walled reinforced concrete products, fiber reinforcement, polypropylene fiber, basalt fiber, steel fiber, compressive strength, tensile strength

The article is devoted to the study of the problem of determining the mechanical properties of vibrating centrifuged concrete with a combined aggregate and fibrous additive, which was basalt fiber. Experimentally obtained data on the optimal consumption of disperse fiber. The dependence of the strength properties of concrete with a combined aggregate on the amount of fiber additive added is graphically presented. Also graphically shows the increase in the speed of the passage of an ultrasonic wave in the body of concrete when determining the prismatic strength. It was found that the presence of porous particles in a concrete mixture facilitates the directed distribution of mineral fibers along the section of the concrete ring. This, in turn, leads to an increase in the fracture toughness of the material. The conclusion is made that the joint introduction of porous and fibrous additives into the concrete mix determines the production (at the same cement costs) of high-strength concretes with an increased crack resistance, as evidenced by the data on the displacement of the boundaries of microcracks formation in the direction of their increase.

Keywords: structures and products of annular section, centrifuged concrete, vibrocentrifuging, mechanical properties of vibrating centrifuged concrete, combined aggregate, fiber additive, basalt fiber, prismatic 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

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

The article is devoted to improving the quality of non-autoclave aerated concrete. The theoretical aspects is considered, the prescription-processing methods is proposed, results of experimental studies is given. The role of the sequence of introduction of the components and mode of preparation of concrete mixture is studied. The effect of hardeners on the properties of aerated concrete is revealed. It analyzes ways of waste disposal and their appropriate application.

Keywords: Concrete, structure, technology, recipe, recovery, sodium sulfate, partially hydrated cement system, an aluminum suspension, a hardening accelerator, coefficient of structural quality