scholarly journals ETHOD FOR MANAGING THE STRUCTURAL-MECHANICAL PROPERTIES OF FOAM CONCRETE MIXTURES

2018 ◽  
Vol 45 (2) ◽  
pp. 183-190
Author(s):  
A. Yu. Bogatina ◽  
V. N. Morgun ◽  
L. V. Morgun
Keyword(s):  
Mechanical Properties ◽  
Solid Phase ◽  
Experimental Studies ◽  
Building Structures ◽  
Foam Concrete ◽  
State Register ◽  
Concrete Mixtures ◽  
Wall Structures ◽  
Plastic Strength ◽  
Scientific Ideas

Objectives At present, the urgency of scientific research aimed at reducing the material consumption of building structures is growing. Since foam concrete proved to be an effective material for wall structures, the aim of the present work was to develop scientific ideas about features of their macrostructural formation at the “viscous to solid” phase transition.Methods The evaluation of plastic strength was carried out according to the patent for invention No. 2316750 (“Method for determining the plastic strength of foam concrete mix” registered in the State Register of Inventions of the Russian Federation on February 10, 2008). Synthetic PO-3NP (TU 38-00-058079999-20-93) and "Arecom-4" galipot glue analogue (TU 31-10) were used as foam generation agents. Control over the kinetics of the plastic strength of the test mixtures of equal density was carried out in five-litre vessels at an interval of 15 minutes for three hours.Results The paper considers the most important features of mass transfer, which control the formation of defectiveness for interporal partitions in foam concrete. From the analysis of theoretical and experimental data, it follows that the ratio between water and surfactant consumption is an important tool for managing the quality of foam concrete mixes. Definingthe optimal relationship between water consumption and the amount of foaming agent allows the maximum amount of surfactants to be located at the gas-liquid interface ensuring minimal defect in the structure of the interporal partitions in the cured concrete.Conclusion The theoretical and experimental studies carried out make it possible to consider the relationship between the consumption of water and surfactant as an important tool for controlling the structural and mechanical properties in foam concrete mixes.

scholarly journals KINETICS OF RHEOLOGICAL CHARACTERISTICS OF FOAM CONCRETE MIXTURE

2021 ◽  
pp. 110-118
Author(s):  
V. Martynov ◽  
◽  
O. Martynova ◽  
V. Elkin ◽  
S. Makarova ◽  
...  
Keyword(s):  
Structural Strength ◽  
Solid Phase ◽  
Chemical Activation ◽  
Experimental Studies ◽  
Concrete Mixture ◽  
Rheological Characteristics ◽  
Foam Concrete ◽  
Plastic Strength ◽  
Kinetics Of ◽  
Cellular Concrete

Abstract. The results of experimental studies are presented, the purpose of which was to study the influence of variable formulation and technological factors on the rheological characteristics of the foam concrete mixture, in particular, the structural strength. This is preceded by an analysis of the process of structure formation of cellular concrete. As a result, it is shown that the properties of cellular concrete are determined by the nature of the distribution of the solid component. The structure of the solid phase is formed at the earliest stages of the formation of cellular products and depends on the rheological characteristics of the mortar and cellular mixture. In the technology of cellular concrete, it is important to synchronize the processes of pore formation and the growth of plastic (structural) strength, which is also associated with a change in the rheological properties of the mixture. Using the methods of mathematical statistics, the influence of the content of the filler in the mixture with cement, the content of the complex additive, and the effect of mechanical chemical activation on the kinetics of the plastic strength of the foam concrete mixture were studied. The kinetic dependences of the plastic strength of the foam concrete mixture in the range of 6 ... 24 hours from the moment of manufacture have been constructed. Each of the 15 curves is maximized by a 3rd-degree polynomial. Based on the obtained dependences, they are differentiated between the first and second derivatives. As a result, the equations of the speed and intensity (acceleration) of the plastic strength of the foam concrete mixture were obtained. According to the results of the previous experiment, carried out according to a three-factor plan, a 4-factor plan was synthesized, in which the aging period of the foam concrete mixture was taken as the fourth factor. The calculated theoretical values of the characteristics of the structural strength of the foam concrete mixture were entered into the matrix. As a result, mathematical models of plastic strength, speed, and intensity of plastic strength of the foam concrete mixture were calculated and the influence of variable factors studied on the isosurfaces of these properties was visualized. The analysis of these dependencies made it possible to determine the characteristic recipe and technological conditions for obtaining a foam concrete mixture with the required values of plastic strength.

scholarly journals The Utilization of Recycled Masonry Aggregate and Recycled EPS for Concrete Blocks for Mortarless Masonry

Materials ◽  
2019 ◽  
Vol 12 (12) ◽  
pp. 1923 ◽  
Author(s):  
Tereza Pavlu ◽  
Kristina Fortova ◽  
Jakub Divis ◽  
Petr Hajek
Keyword(s):  
Mechanical Properties ◽  
Thermal Properties ◽  
Masonry Wall ◽  
Expanded Polystyrene ◽  
Mechanical And Thermal Properties ◽  
Concrete Mixtures ◽  
Wall Structures ◽  
Different Types ◽  
Concrete Blocks ◽  
Recycled Masonry

The main aim of this paper is to carry out the environmentally based enhancement of a concrete mixture containing recycled materials whilst considering natural resource consumption as well as mechanical and thermal property levels. The developed concrete is intended to be used in mortarless masonry wall structures. Ten concrete mixtures with different types and replacement rates of recycled masonry aggregate and recycled expanded polystyrene were prepared, and their mechanical and thermal properties were experimentally investigated. It was found that the use of recycled masonry aggregate led to better thermal properties while maintaining sufficient mechanical properties. On the contrary, the addition of recycled expanded polystyrene did not significantly affect the thermal properties of concrete, but the mechanical properties considerably declined. For this reason, the recycled masonry aggregate is suitable to use as an aggregate for concrete masonry blocks for wall structures.

Impact of Superplasticizing Agents on Physical and Mechanical Properties of Cellular Concrete

2019 ◽  
Vol 974 ◽  
pp. 181-186
Author(s):  
V.A. Perfilov ◽  
V.V. Gabova ◽  
Inessa A. Tomareva
Keyword(s):  
Mechanical Properties ◽  
Pore Structure ◽  
Pore Space ◽  
Experimental Studies ◽  
Basalt Fiber ◽  
Physical And Mechanical Properties ◽  
Foam Concrete ◽  
Cellular Concrete

The effect of superplasticizing, foam agents, various fiber aggregates on the physical and mechanical properties of cellular concrete has been studied. The article covers the results of experimental studies conducted to determine the effect of foam agents PO-6 and PB-2000, as well as polymeric and basalt fiber on the pore structure of foam concrete. The dependence between the change in density and strength of cellular concrete and the structure of its pore space has been determined.

scholarly journals Light concrete based on foam polyamidbe-tonic composition

2019 ◽  
Vol 7 (1) ◽  
pp. 70-75
Author(s):  
Левон Маилян ◽  
Levon Mailyan ◽  
Татьяна Голова ◽  
Tat'yana Golova
Keyword(s):  
Reinforced Concrete ◽  
Energy Efficient ◽  
Concrete Strength ◽  
Experimental Studies ◽  
Fiber Reinforced Concrete ◽  
Strength Characteristics ◽  
Building Structures ◽  
Optimal Composition ◽  
Foam Concrete ◽  
Layer Structures

One of the most important tasks of construction is the use of energy-efficient sin-gle-layer structures based on foam concrete and an increase in their bearing ca-pacity due to the use of fiber reinforcement, which will significantly improve the performance properties of fiber-reinforced concrete. Strength characteristics of fibro-foam concrete reinforced with polyamide granules with various types of filler and recommendations for its use in building structures were obtained. These experimental studies allow us to recommend the optimal composition of polyam-ide concrete compositions.

Study of the Mechanical Properties Development of Concrete Containing Fine Recycled Aggregate

2016 ◽  
Vol 827 ◽  
pp. 267-270 ◽  
Author(s):  
Magdaléna Šefflová ◽  
Tereza Pavlů
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Czech Republic ◽  
Recycled Aggregate ◽  
Future Research ◽  
Building Structures ◽  
Replacement Ratio ◽  
The Czech Republic ◽  
Concrete Mixtures ◽  
Concrete Properties

This paper is focused on the mechanical properties development of fine recycled aggregate (FRA) concrete. FRA was obtained from recycling plant in the Czech Republic. There were prepared four concrete mixtures in the laboratory. The first mixture was reference (REF) with fine natural aggregate (FNA). FNA was replaced in concrete mixtures R10, R20 and R30 in varying replacement ratio. The concrete mixtures R10, R20 and R30 contained 10 %, 20 % and 30 % FRA. There were tested properties of concrete. Finally, it is possible to say that the use of the FRA in concrete influences concrete properties. It is necessary to verify of probably an improvement of compressive strength of FRA concrete in future research. However, FRA concrete is possible to be used in the manufacturing of building structures, but it is necessary to test durability and lifespan of FRA concrete.

Methodology of studying the mechanical properties of composite materials (reinforced concrete)

2018 ◽  
Vol 84 (12) ◽  
pp. 61-67
Author(s):  
V. A. Eryshev
Keyword(s):  
Mechanical Properties ◽  
Reinforced Concrete ◽  
Experimental Studies ◽  
Analytical Relationship ◽  
Hardened Concrete ◽  
Deformation Model ◽  
Joint Work ◽  
Concrete Shrinkage ◽  
Axial Tension ◽  
Tension And Compression

The mechanical properties of a complex composite material formed by steel and hardened concrete, are studied. A technique of operative quality control of new credible concrete and reinforcement, both in laboratory and field conditions is developed for determination of the strength and strain characteristics of materials, as well as cohesion forces determining their joint operation under load. The design of the mobile unit is presented. The unit provides a possibility of changing the direction of loading and testing the reinforced element of the given shape both for tension and compression. Moreover, the nomenclature of testing equipment and the number of molds for manufacturing concrete samples substantially decrease. Using the values of forcing resulting in concrete cracking when the joint work of concrete and reinforcement is disrupted the values of the inherent stresses and strains attributed to the concrete shrinkage are determined. An analytical relationship between the forces and deformations of the reinforced concrete sample with central reinforcement is derived for axial tension and compression, with allowance for strains and stresses in the reinforcement and concrete resulted from concrete shrinkage. The results of experimental studies are presented, including tension diagrams and diagrams of developing axial deformations with an increase in the load under the central loading of the reinforced elements. A methodology of accounting for stresses and deformations resulted from concrete shrinkage is developed. The applicability of the derived analytical relationships between stresses and deformations on the material diagrams to calculations of the reinforced concrete structures in the framework of the deformation model is estimated.

Assessment of the volume activity of α-radioactive wastes on surface and specific contamination by portable γ-spectrometry method

2020 ◽  
pp. 468-473
Author(s):  
I. P. Korenkov ◽  
A. I. Ermakov ◽  
A. B. Mayzik ◽  
T. N. Laschenova ◽  
V. N. Klochkov ◽  
...  
Keyword(s):  
Specific Activity ◽  
Experimental Studies ◽  
Germanium Detector ◽  
Low Energy ◽  
Gamma Ray Spectrometry ◽  
Building Structures ◽  
Germanium Detectors ◽  
Volume Activity ◽  
Β Decay ◽  
Γ Spectrometry

The aim of the study is to evaluate the volume activity of radioactive waste (RW) by surface and specific alpha contamination using portable gamma-spectrometry.Materials and methods. Methods of rapid assessment of the content of α-emitting radionuclides in solid waste of various morphologies using gamma-spectrometers based on germanium detectors are considered. Computational methods for determining the effectiveness of radionuclide registration are presented.Results. The possibility of using portable gamma-ray spectrometry to assess the surface and specific activity of various materials contaminated with α-emitters (232Th, 235U, 238U, 237Np, 239Pu, 240Pu and 241Am) is shown. The calculated values of the registration efficiency of low-energy gamma-emitters obtained by modeling the spatial-energy parameters of the detector are given.To simplify the solution of this problem, the calculation program used 20 standard templates of various geometries (rectangular, cylindrical, conical, spherical, etc.). The main sources of error in the survey of contaminated surfaces, largesized equipment and building structures were investigated.Conclusions. The possibilities of portable γ-spectrometry for estimating the volume of RW based on the surface density of contamination of materials with radionuclides of uranium and transuranic elements are investigated. When using γ-spectrometer with a high-purity germanium detector with a range of γ-quanta extended in the low-energy region, radionuclides such as 232Th, 235U,238U, 237Np, 241Am were determined by their own radiation or by the radiation of their daughter products.The “problem” element is plutonium, for rapid evaluation of which it is proposed, in accordance with the radionuclide vector methodology, to use 241Am, which accumulates during the β-decay of 241Pu.According to calculations, the most likely value of the activity ratio 239Pu/241Am for the object where the work was performed (scaling factor) varies in the range from 5.0 to 9.0.Based on the results of calculations and experimental studies, the parameters of the efficiency of registration of various α-emitting radionuclides by portable γ-spectrometers. It has been found that for germanium detectors with an absolute efficiency of registering a point source of 7÷15%, it is n×10–5÷n×10–4%.

Effects of Vickers Cracks on the Mechanical Properties of Solid-phase-sintered Silicon Carbide Ceramics

2012 ◽  
Vol 27 (9) ◽  
pp. 965-969
Author(s):  
Xiao YANG ◽  
Xue-Jian LIU ◽  
Zheng-Ren HUANG ◽  
Gui-Ling LIU ◽  
Xiu-Min YAO
Keyword(s):  
Mechanical Properties ◽  
Silicon Carbide ◽  
Solid Phase ◽  
Carbide Ceramics ◽  
Silicon Carbide Ceramics ◽  
Sintered Silicon

Study of Rheological Properties of Modified Concrete Mixtures at Vibration

2019 ◽  
Vol 968 ◽  
pp. 96-106
Author(s):  
Oleksandr Pshinko ◽  
Olena Hromova ◽  
Dmytro Rudenko
Keyword(s):  
Mechanical Properties ◽  
Rheological Properties ◽  
Physical Nature ◽  
Concrete Mixture ◽  
Practical Significance ◽  
Vibration Displacement ◽  
Concrete Mixtures ◽  
Variable Quantity ◽  
Vibration Compaction ◽  
Mechanism Of Interaction

Study of rheological properties of concrete mixtures based on modified cement systems in order to determine process parameters. Methodology. To study structural-mechanical properties of modified concrete mixtures of different consistency at their horizontal vibrating displacement an oscillatory viscometer was designed. Results. The optimization of the process of vibration displacement of concrete mixtures with the specification of parameters of vibration impacts taking into account structural-mechanical properties of the mixture is performed. It has been established that the viscosity of the modified cement system of the concrete mixture is a variable quantity, which depends on the parameters of the vibration impacts. Scientific novelty. The mechanism of interaction of the modified concrete mixture with the form and the table vibrator during its vibration compaction is determined. On the basis of this, a model of concrete laying process control is proposed, that allows to predict the ability to form a dense concrete structure. Practical significance. Disclosed physical nature of the process of vibrating displacement of modified concrete mixtures using the principles of physical-chemical mechanics of concrete allows reasonably choose the best options for vibration impacts.

scholarly journals Comprehensive Analysis of the Microstructure and Mechanical Properties of Friction-Stir-Welded Low-Carbon High-Strength Steels with Tensile Strengths Ranging from 590 MPa to 1.5 GPa

2021 ◽  
Vol 11 (12) ◽  
pp. 5728
Author(s):  
HyeonJeong You ◽  
Minjung Kang ◽  
Sung Yi ◽  
Soongkeun Hyun ◽  
Cheolhee Kim
Keyword(s):  
Mechanical Properties ◽  
Tensile Test ◽  
Joint Strength ◽  
Solid Phase ◽  
Welding Process ◽  
High Strength Steels ◽  
High Strength ◽  
Low Carbon ◽  
Friction Stir ◽  
Welding Processes

High-strength steels are being increasingly employed in the automotive industry, requiring efficient welding processes. This study analyzed the materials and mechanical properties of high-strength automotive steels with strengths ranging from 590 MPa to 1500 MPa, subjected to friction stir welding (FSW), which is a solid-phase welding process. The high-strength steels were hardened by a high fraction of martensite, and the welds were composed of a recrystallized zone (RZ), a partially recrystallized zone (PRZ), a tempered zone (TZ), and an unaffected base metal (BM). The RZ exhibited a higher hardness than the BM and was fully martensitic when the BM strength was 980 MPa or higher. When the BM strength was 780 MPa or higher, the PRZ and TZ softened owing to tempered martensitic formation and were the fracture locations in the tensile test, whereas BM fracture occurred in the tensile test of the 590 MPa steel weld. The joint strength, determined by the hardness and width of the softened zone, increased and then saturated with an increase in the BM strength. From the results, we can conclude that the thermal history and size of the PRZ and TZ should be controlled to enhance the joint strength of automotive steels.

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