Heavy Concrete Research Articles

Investigating the Radiation Shielding Properties of Iron Oxide-enhanced Heavy Concrete through Gamma Transmission Method

Investigating the Radiation Shielding Properties of Iron Oxide-enhanced Heavy Concrete through Gamma Transmission Method

The Effect of Dense and Hollow Aggregates on the Properties of Lightweight Self-Compacting Concrete.

The development of self-compacting lightweight concretes is associated with solving two conflicting tasks: achieving a structure with both high flowability and homogeneity. This study aimed to identify the technological and rheological characteristics of the flow of concrete mixtures D1400…D1600 based on hollow microspheres in comparison with heavy fine-grained D2200 concrete and to establish their structural and physico-mechanical characteristics. The study of the concrete mixtures was carried out using the slump flow test and the rotational viscometry method. The physical and mechanical properties were studied using standard methods for determining average density and flexural and compressive strength. According to the results of the research conducted, differences in the flow behaviors of concrete mixtures on dense and hollow aggregates were found. Lightweight concretes on hollow microspheres exhibited better mobility than heavy concretes. It was shown that the self-compacting coefficients of the lightweight D1400...D1600 concrete mixtures were comparable with that of the heavy D2200 concrete. The rheological curves described by the Ostwald-de Waele equation showed a dilatant flow behavior of the D1400 concrete mixtures, regardless of the ratio of quartz powder to fractionated sand. For D1500 and D1600, the dilatant flow behavior changed to pseudoplastic, with a ratio of quartz powder to fractional sand of 25/75. The studied compositions of lightweight concrete can be described as homogeneous at any ratio of quartz powder to fractional sand. It was shown that concrete mixtures with a pronounced dilatant flow character had higher resistance to segregation. The value of the ratio of quartz powder to fractional sand had a statistically insignificant effect on the average density of the studied concretes. However, the flexural and compressive strengths varied significantly more in heavy concretes (up to 38%) than in lightweight concretes (up to 18%) when this factor was varied. The specific strength of lightweight and heavy concrete compositions with a ratio of quartz powder to fractional sand of 0/100 had close values in the range of 20.4...22.9 MPa, and increasing the share of quartz powder increased the difference between compositions of different densities.

Development and evaluation of MgO-grit iron aggregate heavy density concrete for high temperature radiation shielding: Experimental and machine learning approach

This research focuses on the development and evaluation of heavy density concrete (HDC) for radiation shielding, utilizing both experimental and machine learning techniques. Various HDC specimens with different proportions (25 %, 50 %, 75 %, and 100 %) of grit iron aggregate replacing normal weight aggregate, in addition to control specimens with no grit iron scale aggregate, were cast. These samples were subjected to testing at temperatures ranging from room temperature to 1200°C to assess properties such as compressive strength, rebound number, ultrasonic pulse velocity, density loss, mass loss, linear attenuation coefficient (LAC), mass attenuation coefficient (MAC), half-value layer (HVL), tenth-value layer (TVL), and mean free path (MFP). Ensemble learning algorithms were employed using experimental data to predict compressive strength and new empirical expressions were formulated for mechanical and radiation shielding properties, including LAC, HVL, and TVL. The addition of grit iron aggregate, combined with MgO, demonstrated a significant improvement in the mechanical and radiation shielding properties of HDC. This research holds promise for applications in nuclear reactors operating at high temperatures.

IMPRОVЕD FINЕ-GRAINЕD CОNCRЕTЕ FОR PAVING SLABS WITH ОRGANОMINЕRAL ADDITIVES

Currently, putty concrete is widely used in mad construction. But, as can be seen from thе experiments, there is a problem of premature destruction of facing concrete exposed to an aggressive environment. In addition, fine-grained concrete is characterized by a higher level of consumption of Portland cement compared to conventional heavy concrete. One of the possible ways to solve these problems is the introduction of a complex organomineral mixture that promotes binding. Crushed concrete was mainly considered as a local building material. Because at present, consumers are abandoning large fillers that require large funds. A large number and of great importance are works on the study of reinforced concrete. To date, approaches to concrete have not changed, and their research continues to develop.

CONSTRUCTION AND OPERATIONAL PROPERTIES OF CONCRETE ON MODIFIED BINDER

The most important tasks of science in the field of construction: facilitating reinforced concrete structures, accelerating and reducing the cost of technological processes, in particular, abandoning heat treatment of products, increasing the durability of concrete can only be solved by giving special properties to binders. The way to solve this problem lies through the expansion of the range of complex mineral additives. Natural and man-made substances in a dispersed state, insoluble in water and characterized by grain size less than 0.16 mm, are used as mineral additives for binders and concretes. Despite the different effectiveness, mineral additives have a similar qualitative chemical composition (oxides of silicon, aluminum and others). The differences are in their mineralogical composition, the ratio of components and the degree of dispersion, which determine the predominant mechanism of their action in cement systems. Depending on the properties of the mineral additive, it is possible to obtain multicomponent binders for concretes with special properties: fast-hardening, high-strength, sulfate-resistant and others with significant savings in the cement component. The effectiveness of superplasticizers in dispersed systems can be increased due to a different procedure for their introduction or by combining them with finely ground mineral fillers of various chemical nature. The article presents the possibility of obtaining heavy concretes with specified construction and operational characteristics using a complex mineral additive, which includes waste from the tailings of the Balkhash mining and Processing plant and silica, as well as superplasticizers of various natures: MasterGlenium 305, Master Rheobuild 1000K and Master Air 200.

Gamma attenuation and nuclear shieling ability of TeO2/Bi2O3/WO3 glass system

In the present research paper, we present the gamma shielding characterization and the optical properties of a tellurite glass system chemically defined as 64TeO2–15Na2O–5BaO-xBi2O3-(15-x)WO3–1Yb2O3. The study also focused on the evolution of gamma attenuation and optical parameters as the chemical definition of the glass system changed. The optical constants estimated and analyzed include the molar refractivity (Rm), molar polarizability (αmol), reflectance loss, optical transmission, metallization criterion, static dielectric constant, and optical dielectric constant. The values of the mass attenuation coefficient (μρ) other basic shielding quantities were also calculated and analyzed in order to reveal the relative shielding effectiveness of the glasses and their potential for radiation safety applications. For TNY-W/Bi1, TNY-W/Bi2, and TNY-W/Bi3, having Bi2O3 molar concentrations of 0, 5, and 10 mol%, respectively, the density was 5.42 g/cm3, 5.56 g/cm3, and 5.67 g/cm3, while the molar volume had values of 29.119 cm3/mol, 30.491 cm3/mol, and 31.964 cm3/mol, respectively. The Rm and αmol increased from 17.72 to 19.68 cm3/mole and 7.03 × 10−24 cm3 to 7.81 × 10−24 cm3, respectively. All other estimated optical parameters vary according to glass composition and the refractive index. The values of μρ fluctuated between 0.0344 and 56.4869 cm2/g for TNY-W/Bi1, 0.0351 and 59.3506 cm2/g for TNY-W/Bi2, and 0.0368 and 61.8444 cm2/g for TNY-W/Bi3. For a glass thickness of 10 mm and at 15 keV, the absorbed dose rates in TNY-W/Bi1, TNY-W/Bi2, and TNY-W/Bi3 were 50 μR/h, 52 μR/h, and 53 μR/h, respectively. The increase in Bi2O3 content improved the photon and energy absorption capacities of the TNY-W/BiX glasses. The replacement of WO3 with Bi2O3 in the glass system increased photon buildup factors in the glasses as well. The present glasses showed better photon absorption capacities than light and heavy concrete, standard shielding glasses, alloys, and rock samples.

The Effect of Cellulose Fiber on the Bending Strength of Autoclaved Aerated Concrete

Autoclaved aerated concrete is becoming an increasingly popular building material, and for good reason. It is ecological, energy efficient, strong, and durable. Studies show that the production of autoclaved aerated concrete saves 85% of energy compared to the production of heavy concrete. However, the use of steel reinforcement in large-sized aerated concrete products leads to deterioration of thermal insulation properties, corrosion, and destruction of the material. Replacing steel reinforcement with discrete fiber strands can solve this problem. The fiber does not affect the thermal insulation properties, is not prone to corrosion, and can be evenly distributed over the entire volume of the product.

Evaluation of shielding performance and light emission characteristics of luminescent radiation shields using Gd2O2S

ABSTRACT Gadolinium oxysulfide (Gd2O2S: GOS) has a large absorption cross-section for thermal neutrons and a mass density similar to that of iron used for shielding against X and γ-ray radiation. During GOS scintillator production process, its waste is also generated. If GOS waste can be used as an effective shielding material, it is worthwhile as beneficial use of the waste. We developed a novel radiation-shielding material using GOS waste. The developed shielding material can shield X, γ-rays and thermal neutrons more efficiently than conventional shielding materials and emit visible light due to leaked radiation when the shielding material is damaged, which subsequently be used to check the integrity of shielding using visible light. In this study, two types of shields, concrete and mortar with GOS as the aggregate and epoxy resin with GOS were prototyped and tested for radiation transmission. Results indicate that GOS shielding has a 10% higher shielding ability for X and γ-rays than heavy concrete with iron as aggregate. Additionally, the same shielding effect for thermal neutrons was attained at 1/10 the thickness of heavy concrete. Thus, using GOS waste is not only cost effective but also contributes to a circular economy.

ASSESSMENT OF THE POSSIBILITY OF USING RECYCLED COARSE AGGREGATE IN A WOOD-SOIL CONCRETE SLAB

Problem statement. During the process of post-war reconstruction in Ukraine, there will be a need for a large number of affordable and ecological building materials, especially in the part of restoration and construction of low-rise buildings. Such building materials can be soil-concrete and aggregates from crushed concrete waste. The proposed constructive solution of the ribbed floor, in which the ribs are made of pine beams and OSB sheets, and the slab part is made of soil concrete on fixed formwork. The purpose of the article is to determine the optimal composition of the soil-concrete mixture using crushed stone obtained after crushing concrete scrap, taking into account the configuration of the wood-soil concrete slab, to determine the strength of soil-concrete of this composition, to determine the possibility of using recycled coarse aggregates. Conclusions. Based on the results of determining the optimal composition of soil-concrete, it was established that the maximum compressive strength is achieved when the mass content of the binder in the cement-soil mixture is at the level of 20 %. Taking into account the configuration of the slab part of the floor, a fraction of 5...7.5 mm is accepted for coarse aggregate. During the test of soil-concrete samples with recycled aggregate with a mass content of 10 %, 20 % and 30 %, the compressive strength of soil concrete decreased. Obviously, the presence of a clay component (loam) in the mixture reduces the adhesion in the contact zone between the aggregate and the soil-concrete, which increases the heterogeneity of the entire structure of the soil-concrete. Thus, the use of natural or recycled coarse aggregates in soil-concrete is impractical. Taking into account the determined strength of soil-concrete without aggregate, a scheme of combined concreting of the soil-concrete slab is proposed – heavy concrete above the rib and soil-concrete in the overhangs. In this case, there is a need for research on the possibility of using recycled coarse aggregate of the required size in heavy concrete.

Valorization of steel slag into sustainable high-performance radiation shielding concrete

The disposal of steel slag (SS) has become a serious ecological problem due to the waste of massive land resources. This study reveals the huge potential of recycling SS as heavy aggregates to develop radiation shielding concrete (RSC). The physical characteristics, radiation attenuation capabilities, microstructure, and environmental and ecological impacts of SS-based RSC are comprehensively evaluated and compared with those of normal concrete and the commonly used heavy concrete. The test results indicate that SS-based RSC is prospective to substitute the commonly used heavy concrete, emerging as a sustainable and efficient material for radiation shielding in nuclear energy engineering. Specifically, due to the reaction of cementitious active substances in the surface of SS, the developed SS-based RSC exhibits a fantastic interfacial transition zone (ITZ), and a compact pore structure, thereby showing excellent mechanical properties. The maximum compressive strength of developed SS-based RSC reaches 47.4 MPa. In terms of gamma ray attenuation property, due to the introduction of heavy nuclei and the increase in density, the gamma ray attenuation capacity of developed SS-based RSC is 17.2 % higher than that of normal concrete. The neutron attenuation property is also slightly enhanced due to the refinement effect of SS on pore structure of RSC. Life cycle assessment and unit cost evaluation results demonstrate that compared with barite based-RSC, SS-based RSC can save 97.6 % in cost, 52.0 % in energy consumption, and 70.4 % in carbon emission. The developed SS-based RSC exhibits excellent mechanical properties and radiation attenuation capacities, contributing to the further application of radiation shielding materials. Besides, this approach achieves the high-value recycling of SS, providing new insights for the utilization of high-density solid wastes.

ПРИМЕНЕНИЕ НЕИЗВЛЕКАЕМЫХ ТРУБЧАТЫХ ПУСТОТООБРАЗОВАТЕЛЕЙ И ЛЁГКИХ БЕТОНОВ ДЛЯ СНИЖЕНИЯ СЕЙСМИЧЕСКОГО ВОЗДЕЙСТВИЯ НА ЗДАНИЯ

Annotation. The article gives examples of buildings and structures, successfully and unsuccessfully designed and built, shows their characteristic features, analyzes publications that justify the need to reduce the weight of structures; reducing the location of the center of gravity of the masses, the use of constructive solutions of the building itself capable of counteracting seismic effects. An example of the design and calculation of two design options for a twelve-story residential building of various weights using heavy and lightweight concrete and non-removable cardboard-polyethylene void formers with a circular cross section with a diameter of 159 mm is given as one of the methods aimed at reducing seismic impact. Based on the studies performed, it was concluded that it is expedient to use non-removable void formers in combination with lightweight concrete to reduce the mass of reinforced concrete structures and heavy concrete to reduce the center of gravity of the building, and as a result, reduce the seismic impact.
 Subject of study. The subject of the study is to reduce the mass of reinforced concrete structures of high-rise buildings and their center of gravity, as well as the construction of the building itself in seismic zones.
 Materials and methods. To reduce the mass of reinforced concrete structures, the frame was designed and the center of gravity of a twelve-story residential building was calculated in two options - the first option: the use of heavy reinforced concrete completely 2.5 t/m3 and solid floor slabs 22 cm thick; the second option is the use of heavy reinforced concrete with a density of 2.5 t/m3 to cover the basement and the lower four floors, the rest of the upper floors using light reinforced concrete with a density of 1.7 t/m3 and non-removable cardboard-polyethylene void formers with a diameter of 159 mm for floor slabs. The possibility, expediency and application of building design according to the second option are substantiated.
 Results.
 1) Reducing the center of gravity of the building by 16.3%.
 2) Reducing the mass of the building while maintaining the standard loads: 20.5%.
 3) The cumulative reduction in the mass of reinforced concrete elements is 30.7%.
 Conclusions. The proposed design of a monolithic twelve-story residential building using heavy concrete on the lower floors and lightweight concrete in combination with non-removable cardboard-polyethylene tubular hollow formers of circular cross section with a diameter of 159 mm on the upper floors, providing a significant reduction in the mass and center of gravity of the building, is a possible and expedient way to build in seismically dangerous regions

Study of Compressive Strength of Concrete Using in the Form of 30% Ceramics and 70% Polymer Crushed Stone as Adhesive

This study was conducted to determine the influence of mechanical properties of polymer concrete by compressive test after the addition of ceramic materials and crushed stone, polymers as adhesives. Polymer paste mixture 1:2 (catalyst:resin). Tests on cube-shaped specimens with dimensions of 15 x 15 x 15 cm are 3 days old. From the test results, it was obtained that the highest compressive strength of concrete BPK30(1) 27.66 Mpa with a test specimen weight of 6,537 kg was found in a mixture of polymer paste with a content of 20% and the lowest compressive strength of polymer concrete was found in a mixture of polymer concrete BPK30(3) with a content of 50% polymer paste with a test specimen weight of 6,506 kg, which was 16.60 Mpa. While BPK30(2) with a resin content of 40% produces concrete compressive strength equal to test specimen 1 of 27.66 Mpa. With a specimen weight of 6,548 kg. From the test results, there was a decrease in the compressive strength value of concrete from BPK30(2) to BPK30(3) by 11.06 Mpa. All samples fall under the classification of heavy concrete of high quality (high strength concrete).

ENVIRONMENTAL ASPECTS OF PROCESSING GRANULAR FILTERS FOR PRIMARY ALUMINUM REFINING

This article presents the results of experimental studies on the involvement in the processing of used filters from ash and slag waste used in the refining of primary aluminum as a filler in the production of concrete for building products. The research was carried out within the framework of grant funding from the Science Committee of the Ministry of Science and Higher Education of the Republic of Kazakhstan under the competition «Zhas Galym» under the project IRN AR19175493 «Development of technology for refining primary aluminum with filters with an active surface». The recycling of used grain filters was carried out in three stages: preliminary processing of filter grains to remove aluminum scrap; metallurgical processing of separated aluminum scrap by remelting in an induction crucible furnace and refining using complex technology described by the authors in the work; obtaining a concrete mixture based on crushed waste filter grains, quartz sand and bauxite sludge, screenings from crushing rocks with a fraction of 20–30 mm and Portland cement to obtain samples of construction products. According to the test results, the tensile strength of concrete samples of building products is 20.89–37.75 MPa, depending on the content of Portland cement (from 20 to 40 %) and corresponds to the class of heavy concrete. Keywords: aluminum, granular filter, ash, waste, recycling.

An extensive benchmark analysis of advanced ceramic-concretes towards strategic material selection for nuclear applications and waste management

Ceramic concretes, with their exceptional durability and ability to incorporate a high percentage of heavy metal oxides, are of critical importance for nuclear radiation facilities, offering superior radiation attenuation characteristics essential for long-term safety and protection. This study presents a detailed evaluation of the gamma-ray shielding properties of various concrete composites, including Standard Concrete and Heavy Concretes (HC series), with densities ranging from 1.94 g/cm3 to 4.54 g/cm3. Utilizing computational methods, we analyzed several gamma-ray and neutron shielding parameters such as mass attenuation coefficients, linear attenuation coefficients, half and tenth value layers, mean free paths, exposure build-up factors, effective atomic number (Zeff), effective electron density (Neff), fast neutron effective removal cross-section (ΣR), and photon transmission factors (TFs). Our research reveals that the shielding efficacy of concrete is intrinsically linked to its density and elemental composition, with higher densities and the incorporation of heavy elements leading to enhanced attenuation capabilities. Among the concretes studied, Limonite with Steel Punch LS-a, which contains 74.53% Fe in its structure, exhibited the lowest transmission factors (TFs) across all tested thicknesses and energy levels (0.662, 1.1732, and 1.3325 MeV), indicating its superior photon attenuation potential. It can be concluded that the concrete samples with a higher Fe (iron) content in their structure demonstrate clear superiority in gamma-ray attenuation properties.

Updates of the removable biological shielding blocks inside of the test cell, part of the test systems of IFMIF-DONES

The International Fusion Materials Irradiation Facility - DEMO Oriented Neutron Source (IFMIF-DONES) is a facility which is designed under the framework of the EU fusion roadmap. It is going to be an essential irradiation facility for testing and qualifying candidate materials under severe irradiation conditions of a neutron field having an neutron irradiation effect on materials like the one expected in a commercial fusion power reactor. The material specimens are irradiated in a containment structure named Test Cell (TC), which is part of the Test Systems (TS).The first protecting „barrier” against irradiation affecting the surrounding of the TC, are the Removable Biological Shielding Blocks (RBSBs). These ∼9 m height, ∼80 tons elements, which are formed by stainless steel liners filled with heavy concrete, need to be remotely handled as after the first experiments they will get dose rates above the hands-on limit. Irradiation will also result in a large nuclear heat power deposited in the shielding blocks, therefore needs to be actively water cooled by a system of embedded pipes to control the temperature.In this paper the updated design of the RBSBs is described, including the latest achievements and proposals for feasible manufacturing, lifting and positioning possibilities of the blocks inside of the TC respecting the given tolerances.

Comparative ultimate tensile strength of concrete and fibre concrete

The study is aimed at comparing the ultimate tensile stresses with respect to the crack resistance criteria of concrete and fibre concrete based on theoretical and experimental data. The resistance of concrete to cracking is determined by the ability to resist the formation and growth of cracks. According to the cracking resistance criterion, concrete deformations are limited by the ultimate tensile strength of the concrete matrix, insignificant for heavy concrete, and the introduction of dispersed reinforcement can significantly increase its tensile strength and crack resistance. Recommended methods for calculating the crack resistance of fibre concrete structures are based on the procedures, used to calculate the crack resistance of structures, reinforced with bars, and incompletely account the features of a fibre concrete as a structural material. In addition, although even a significant crack opening cause no effect on the bearing capacity of fibre concrete structures, generally accepted methods for calculating fibre concrete structures exclude cracking. The article discusses various options for calculating the ultimate tensile stresses of concrete and fibre concrete for ensuring crack resistance based on reference normative and experimental data. Dispersed reinforcement with metal fibres was established at least doubling the ultimate tensile strength according to the crack resistance criterion with even lowmodulus fibres effectively improving the crack resistance, which ensures a more reliable operation of structures, including during winter concreting.

Study of Using Electrical Heavy Concrete in the Improvement of Urban Areas

In regions with negative average daily temperatures, the development of the construction sector, including transport infrastructure facilities, requires increasing the efficiency of heating systems and deicing systems, while reducing the material consumption of their production. In the study, samples with dimensions of 70x70x70 mm and products with dimensions of 500 × 500 × 50 mm were made from electrically conductive coarse aggregate concrete. Additives of industrial soot suspension - 7% and carbon fiber - 1% were used as modifiers. The additives were introduced individually and in combination. The developed compositions ensure the mechanical compressive strength of concrete on the 28th day of more than 40 MPa. The combined use of modifiers allows the surface of the product to be heated from 21°C to 34°C within 30 minutes. Physicochemical studies of the compositions conducted after 3 cycles of heating and cooling showed optimal homogenization of carbon-containing materials and the absence of chemical interaction between carbon fiber and components of the mineral matrix. The obtained indicators of electrical and mechanical properties prove that it is possible to manufacture products based on the optimal composition that provide repeated heating and are optimal for use in the improvement of urban areas.

The influence of cyclic temperature and humidity effects on the compressive strength of heavy concrete

The paper presents the results of experimental studies of the effect of cyclic exposure to elevated temperatures up to 90оС and 150оС and moistening to full water saturation on the strength of heavy concrete. Quantitative data on the change of concrete strength properties depending on the influence factors are obtained. Proposals are formulated to take into account in calculations the influence of heating and moistening modes on the strength of concrete in axial compression. Under cyclic exposure to elevated temperatures and subsequent moistening at normal temperature, there are significant changes in the compressive strength of concrete at different stages of each cycle. At the short-term heating stage, the reduction in the prismatic strength of the concrete amounted to 15 - 22% of the concrete strength before heating. Prolonged isothermal heating results in a 13 - 25% increase in concrete strength. At the stage of subsequent moistening of concrete after heating, there is a decrease in strength by 25 - 27%, while the relative magnitude of strength reduction does not significantly depend on the number of previous cycles. In the investigated interval of up to twenty-five cycles of exposure to elevated temperatures and moistening, the greatest reduction in concrete strength was observed in the first and last cycles. For cycles with heating temperature up to 90⁰C at short-term heating at the beginning of the second cycle the concrete strength drop was 45.5%, and the concrete strength drop at short-term heating for the 25th cycle was 9.7%. For cycles with heating temperature of 150⁰C the strength drop was 45.9% and 52.5%, respectively. The accepted experimental mode according to the formula of cycle (6+1) + (6+1) is the most unfavorable for the strength of concrete under cyclic effects of elevated temperatures and subsequent moistening.

Evaluation of peel resistance of paint coatings depending on the roughness of the cement substrate

The object of the study is paint and varnish coatings of cement concrete. The goal is to evaluate the stress-strain state of coatings under the action of temperature depending on the geometry of the substrate roughness relief. The results of calculating the distribution of stresses over the cross section of the coatings and the possibility of their peeling are presented. The SCAD Office software module was used for the calculation. Heavy concrete was considered as the substrate. Polyvinyl acetate cement PVAC paint was used as a paint composition. The calculations were carried out for the conditions of Moscow. A comparison is made of the stresses in the coating on a smooth and rough surface. I has been found that an increase in the relief angle of the substrate surface roughness does not cause a significant change in the magnitude of stresses. The stress concentration in the zone of contact between the coating and the rough surface of the cement substrate has been established. A diagram of the distribution of stresses in the PVAC coating is presented. It was revealed that at some distance from the zone of the microdepression of the substrate surface relief, an increase in stresses is observed, which, depending on the angle of inclination of the relief, are s х = (1.007-1.021) MPa. At the peak of the relief, the stress values in the contact zone are less and amount to 0.403-0.441 MPa. The influence of the substrate roughness has practically no effect on the values of normal stresses on the coating surface, which are 0.835-1.001 MPa. The probability of peeling off the coating is estimated. The possibility of peeling of the coating has been established, tk. stress values are less than the adhesion strength, which is 0.9-1.1 MPa. It is recommended that in order to increase the resistance of coatings to peeling, strive to create a uniformly distributed roughness of the substrate surface.

INFLUENCE OF PLASTICIZING AND AIR-ENTRAINING ADMIXTURES ON CONCRETE PROPERTIES

In the modern construction industry of Kazakhstan, to ensure the needs of the market, there is an urgent essential to improve the quality of concrete and expand its functional purpose. To a large extent, this is achieved by designing concrete as composite materials with different structures, quantities and nature of components. The multicomponent composition makes it possible to effectively manage the structure formation processes of the concrete cementing matrix and obtain concretes with the required properties. This article presented the effect of plasticizing and air-entraining admixtures on the properties of heavy concrete. The compositions of concrete mixture with plasticizing and air-entraining admixtures were selected. The results of study of plasticizing and air-entraining admixtures effect on average density, workability, compressive strength of concrete samples are presented. The effectiveness of introduction of a complex admixtures was evaluated in order to further improve operational properties of concrete. The plasticizing effect makes it possible to increase workability of concrete mortar while by reducing water-cement ratio from 0,5 to 0,38. Due to this, density and strength of concrete increased while improving operational characteristics. The combined effect of plasticizing and air-entraining admixtures had a positive effect on mobility of concrete mortar and its strength of concrete samples. The significant strength of 47,2 MPa was achieved with the combined introduction of a plasticizing and air-entraining admixtures in the amount of 1,2% and 0,5% of the cement weight, thereby increasing the strength of concrete samples by 32% compared to the control sample.