Theoretical Basis of Formation Highly Organized Porous Structure of Aerated Concrete

2019 ◽  
Vol 945 ◽  
pp. 309-317 ◽  
Author(s):  
L.A. Suleymanova ◽  
I.A. Pogorelova ◽  
M.V. Marushko
Keyword(s):  
Porous Structure ◽  
Cellular Structure ◽  
Control Cell ◽  
Air Entrainment ◽  
External Pressure ◽  
Average Density ◽  
Concrete Mixture ◽  
Concrete Technology ◽  
Aerated Concrete ◽  
Cellular Concrete

Theoretical principles of the formation of highly organized porous structure of cellular concrete are developed, based on model concepts of the dynamics of the expanding gas cavity in the liquid phase as a single control cell. The peculiarities of controlling the formation of cellular structure of aerated concrete based on the balance of forces in a three-phase disperse system on the model "gas pore - molding mixture" are revealed and a coalescing-aggregate scheme for porosity formation of the aerated concrete mixture is proposed. It is shown that, in accordance with the refined Rayleigh-Plesset equation, the determining factor in the formation of the cellular structure of aerated concrete is the pressure over the mixture to be poroused, the effect of the porosity being achieved by reducing the external pressure to the vacuum level. The division of pores by size in anaerated concrete mixture is proposed. The maximum pore size is determined by the capillary Laplace constant. The prospects of aerated concrete technology are associated with a decrease in the maximum and average size of cellular pores, as well as methods for eliminating pores of air entrainment and segmented pores. Reducing of the size of the pores will be reflected in the decrease of the Bond quantity and in the increase of the importance of capillary forces in the formation of the porous structure of aerated concrete. The concepts of the types of cellular structures are developed, depending on the average density and their boundaries for cellular concrete are established.

scholarly journals OPTIMIZATION OF RECEPTURAL-TECHNOLOGICAL PARAMETERS OF MANUFACTURE OF CELLULAR CONCRETE MIXTURE

2020 ◽  
pp. 30-36 ◽  
Author(s):  
Nataliya Alfimova ◽  
Sevda Pirieva ◽  
D. Gudov ◽  
I. Shurakov ◽  
Elena Korbut
Keyword(s):  
Production Efficiency ◽  
Mechanical Characteristics ◽  
Average Density ◽  
Concrete Mixture ◽  
Technological Parameters ◽  
Number Of Factors ◽  
Aerated Concrete ◽  
The Moment ◽  
The Impact ◽  
Cellular Concrete

aerated concrete at the moment is one of the perspective thermal insulation materials. However, the production of high-quality aerated concrete products is associated with a number of difficulties, primarily related to the features of the manufacturing technology and, in particular, to the formation of its structure during the period of gas evolution and the impact on this process of a large number of factors. The best conditions for the formation of cellular concrete are created when the maximum gas release and the optimum values of the plasticity-viscous characteristics of the aerated concrete mixture are found. Achieving optimal conditions is extremely difficult, which leads to a deterioration in the physico-mechanical characteristics of the final products. One of the ways to solve this problem is to increase the amount of mixing water, however, along with a positive effect (reducing the viscosity of the system), this leads to a decrease in the gas-holding capacity of the mixture. In this connection, the possibility of increasing the production efficiency of the cellular concrete mixture by optimizing the recipe-technological parameters was considered. With the help of the method of mathematical planning, a three-factor experiment was carried out, as the factors of variation were: the duration of the preliminary aging of the mixture, the dosage of the blowing agent and the water-hard ratio, the output parameters were the compressive strength and the average density of the final products. The obtained results made it possible to reveal the regularities of the change in the output parameters from the variable factors and to establish that the preliminary aging of the mixture before the introduction of the gassing agent positively affects the structure and, as a consequence, the physico-mechanical characteristics of the final products.

Composite Binder for Structural Cellular Concrete

2019 ◽  
Vol 945 ◽  
pp. 53-58 ◽  
Author(s):  
M.Y. Elistratkin ◽  
E.S. Glagolev ◽  
M.V. Absimetov ◽  
V.V. Voronov
Keyword(s):  
Building Materials ◽  
Negative Impact ◽  
Average Density ◽  
Construction Costs ◽  
Competitive Situation ◽  
Composite Binder ◽  
Mineral Supplements ◽  
Autoclaved Aerated Concrete ◽  
Aerated Concrete ◽  
Cellular Concrete

Non-autoclaved aerated concrete is the only viable alternative to gas silicate when organizing its manufacture on the basis of regional small and medium capacity production. This aims to improvement the competitive situation on the building materials market and optimizing the construction costs. The possibility of expanding the application field of this material due to the increase in strength characteristics while maintaining an unchanged average density is of special interest. The guarantee of proposed solutions economic and technical efficiency is the transition from traditional portland cement to composite binders based on it. The article discusses the quantity and composition of the mineral supplements feasibility to optimize the binder properties of the problem peculiarities to reduce consumption of cement and chemical modifiers that increase the rate of curing and totals of non-autoclaved aerated concrete investigated compatibility issues between components to eliminate their negative impact on the formation of porous structure of the final product.

AERATED CONCRETE WITH THE USE OF FERRUGINOUS QUARTZITE PROCESSING WASTE

2020 ◽  
Vol 5 (4) ◽  
pp. 230-242
Author(s):  
Myroslav Malovanyy ◽  
◽  
Oksana Ilyash ◽  
Oleksiy Povzun ◽  
Valeriy Kalynychenko ◽  
...  
Keyword(s):  
Compressive Strength ◽  
Mass Fraction ◽  
Average Density ◽  
Ferruginous Quartzite ◽  
Processing Waste ◽  
Concrete Mixtures ◽  
Processing Plants ◽  
Magnetic Enrichment ◽  
Aerated Concrete ◽  
Cellular Concrete

Waste (tailings) of mining and processing plants of Kryvbas were studied by the stages of their magnetic enrichment. The granulometric compositions of the tailings, the amount of iron (total and magnetic) and the mass fraction of solid in them are determined. The expediency of disposing of ferruginous quartzite waste at the first stage of enrichment as a silica component in cellular concretes is proved. Optimal compositions of aerated concrete mixtures are determined based on the following criteria: the average density of cellular concrete in the dry state and its compressive strength.

Low Density Cellular Concrete Made of Reftinskaya SDPP Fly Ash

2017 ◽  
Vol 265 ◽  
pp. 124-128 ◽  
Author(s):  
A.A. Vishnevskiy ◽  
F.L. Kapustin
Keyword(s):  
Fly Ash ◽  
Single Layer ◽  
Drying Shrinkage ◽  
Strength Properties ◽  
Low Density ◽  
Concrete Technology ◽  
Concrete Production ◽  
Aerated Concrete ◽  
Increased Strength ◽  
Cellular Concrete

There is experience of the production and use of low density autoclaved aerated concrete. It is shown that fly-ash from Reftinskaya State District Power Plant efficiently substitutes the quartz sand aerated concrete technology. Its use opens up additional opportunities for AAC with the density of 300-400 kg/m3. In order to optimize the structure and properties it has been suggested to introduce the gypsum aerated concrete additive into the autoclave in the amount of 3-5% by weight of the dry components. The introduction of gypsum ensures the creation of a uniform homogeneous structure, resulting in the increased strength properties and reduced drying shrinkage. The resulting aerated concrete has thermal conductivity of 0.075-0.100 W/m·K, it allows using and creating single-layer fencing structures without additional insulation. The low-density gas-ash concrete production allows extending the scope of cellular concrete application and increasing its competitive advantages over other walls and insulating materials.

On a formula finding fractal dimension

2020 ◽  
Vol 1 (104) ◽  
pp. 19-22
Author(s):  
Kh. Kamilov ◽  
A. Zaitov ◽  
A. Tulaganov ◽  
A. Tulaganov
Keyword(s):  
Fractal Dimension ◽  
Porous Structure ◽  
Pore Structure ◽  
Disordered Systems ◽  
Fractal Theory ◽  
Theoretical Description ◽  
Average Density ◽  
Factors Affecting ◽  
Highly Porous ◽  
Cellular Concrete

Purpose: The article is devoted to the determination of the fractal dimension of cellular concrete, in particular foam concrete, and the further clarification of the relationship between fractal dimension and porosity and average density of cellular concrete. Design/methodology/approach: In the theoretical description of disordered systems, the fundamentals of fractal theory are actively used, which allow obtaining statistical indicators of chaotic natural and artificially disordered systems, which include cellular concrete. The parameters of the pore structure are difficult to quantify by conventional methods because of the complexity and irregularity of the pore structure due to their random distribution. Findings: Formulas for calculating the fractal dimension and average density of highly porous material are calculated and proposed. The formula for calculating the average density takes into account the density of the material between the pore walls. Research limitations/implications: The calculation of the fractal dimension is one of the main factors affecting the practical application of the theory of fractals, a natural problem arises on a theoretical basis to justify these calculations. Practical implications: The formulas proposed in this work for calculating the fractal dimension and density of a highly porous structure improve research on methods for producing substances with a controlled fractal structure, which will help create materials with unusual mechanical properties, density, and porosity. Originality/value: The formula for calculating the fractal dimension obtained in the work improves the well-known Hausdorff-Bezikovich formula. On the other hand, it makes it possible to obtain a highly porous structure with a given density of the material under study.

scholarly journals МЕТОДИКА ОПРЕДЕЛЕНИЯ СОСТАВА ГАЗОБЕТОННОЙ СМЕСИ ТРЕБУЕМОЙ ПРОЧНОСТИ НЕАВТОКЛАВНОГО ЯЧЕИСТОГО ГАЗОБЕТОНА НА МИКРОЗАПОЛНИТЕЛЕ ИЗ ДИСПЕРГИРОВАННОГО ГРАНИТНОГО ОТСЕВА

2019 ◽  
Author(s):  
Yu. Samuilov
Keyword(s):  
Construction Material ◽  
Total Content ◽  
Strength Characteristics ◽  
Concrete Mixture ◽  
Design Strength ◽  
Factors Affecting ◽  
Cement Binder ◽  
Aerated Concrete ◽  
Reference Samples ◽  
Cellular Concrete

В статье приведены результаты исследований в виде методики определения состава смеси для изготовления ячеистого газобетона неавтоклавного твердения на цементном вяжущем и микрозаполнителе из диспергированного гранитного отсева с заданной проектной прочностью. Представлены сведения о компонентах проектируемой газобетонной смеси, включая: вяжущее, микрозаполнитель, газообразующие добавки и ПАВ. Указана технология приготовления образцов. Разработанная методика обеспечивает учет таких факторов, как: проектируемая плотность ячеистого бетона, соотношение требуемого количества микрозаполнителя и цемента, соотношение расхода воды и суммарного содержания твердых компонентов смеси, проектируемая влажность ячеистого бетона. Данная методика является дополнением к методике определения состава газобетонной смеси требуемой плотности неавтоклавного ячеистого газобетона на микрозаполнителе из диспергированного гранитного отсева 1. Она позволяет с достаточной точностью подбирать набор основных параметров, влияющих на прочностные характеристики ячеистого бетона, благодаря чему достигается проектируемая прочность этого строительного материала. В представленной методике продемонстрированы графические зависимости прочности неавтоклавного ячеистого газобетона на микрозаполнителе из диспергированного гранитного отсева от основных влияющих на нее параметров. На основании полученных зависимостей были изготовлены и испытаны эталонные образцы ячеистого бетона. Данные образцы были выполнены из смеси, параметры которой соответствовали максимальным прочностным показателям. Результаты испытаний эталонных образцов легли в формулу, которая связывает проектируемую прочность ячеистого бетона и влияющие на нее факторы. Аналитическая работа с этой формулой в сочетании с методикой 1 позволяет: получить ячеистый бетон заданной прочности сэкономить вяжущее без снижения его прочностных характеристик расширить диапазон ассортимента неавтоклавных ячеистых газобетонов по прочностным характеристикам обеспечить необходимую подвижность смеси, сохранив проектную прочность готового ячеистого бетона. В статье приведены данные о результатах апробации разработанной методики, подтверждающие ее эффективность.The article presents the results of research in the form of methods for determining the composition of the mixture for the manufacture of aerated cellular concrete non-autoclaved hardening on cement binder and microfill from dispersed granite screenings with a given design strength. Information is given about the components of the designed aerated concrete mixture, including: astringent, micro-filler, gas-forming additives and surfactants. The technology of preparation of samples is shown. The developed method takes into account such factors as: the projected density of cellular concrete, the ratio of the required amount of micro-filler and cement, the ratio of water consumption and the total content of solid components of the mixture, the projected moisture content of cellular concrete. This technique is an addition to the method of determining the composition of the aerated concrete mixture of the required density of non-autoclaved aerated aerated concrete on a microfiller from dispersed granite screenings 1. It allows to select with sufficient accuracy a set of the main parameters influencing strength characteristics of cellular concrete thanks to what the projected durability of this construction material is reached. In the presented method, the graphical dependences of the strength of non-autoclaved aerated cellular concrete on a microfill from dispersed granite screenings on the main parameters affecting it are demonstrated. On the basis of the received dependences reference samples of cellular concrete were made and tested. These samples were made from a mixture whose parameters corresponded to the maximum strength parameters. The test results of the reference samples formed a formula that binds the projected strength of cellular concrete and the factors affecting it. Analytical work with this formula, in combination with the method 1, allows: to obtain cellular concrete of a given strength to save astringent, without reducing its strength characteristics to expand the range of non-autoclaved cellular aerated concrete by strength characteristics to provide the necessary mobility of the mixture, while maintaining the design strength of the finished cellular concrete. The article presents data on the results of testing the developed technique, confirming its effectiveness.

scholarly journals EFFECT OF POROUS STRUCTURE ON SOUND ABSORPTION OF CELLULAR CONCRETE

2020 ◽  
Vol 3 (2) ◽  
pp. 5-18 ◽  
Author(s):  
R.S. Fedyuk ◽  
A. Baranov ◽  
Y.H. Mugahed Amran
Keyword(s):  
Open Porosity ◽  
Sound Absorption ◽  
Concrete Mixture ◽  
Sound Waves ◽  
Foam Concrete ◽  
Mechanical Adhesion ◽  
The Matrix ◽  
Reduce Shear Stress ◽  
The Mathematical Model ◽  
Cellular Concrete

the compositions of gas and foam concrete with improved acoustic characteristics were developed. The optimal form of porosity, which contributes to the absorption of sound waves, both in the range of audible frequencies and at infrasonic and ultrasonic frequencies, is revealed. The mathematical model for designing sound-absorbing concrete was improved, taking into account both the porosity of the composite and the influence of the porous aggregate. The laws of synthesis of aerated concrete and foam concrete are established, which consist in optimizing the processes of structure formation due to the use of a polymineral cement-ash binder and blowing agent. The composition of the composite intensifies the process of hydration of the system, which leads to the synthesis of a polymineral heterodisperse matrix with an open porosity of more than 60%. Peculiarities of the influence of the “Portland cement – aluminosilicate – complex of modifiers” system on the rheology of the concrete mixture was identified, which can significantly reduce shear stress and create easily formed cellular concrete mixtures. The increased activity and granulometry of aluminosilicates predetermine an increase in the number of contacts and mechanical adhesion between particles during compaction, strengthening the frame of inter-pore septa. The mechanism of the influence of the composition of the concrete mixture on the microstructure of the composite is established. The presence of refined aluminosilicates and a complex of additives in the system along with cement contribute to the synthesis of the matrix with open porosity, thereby increasing the sound absorption coefficient.

scholarly journals New Method for Diagnostic of Heat Engineering and Mechanical Properties of Cellular Concrete

2019 ◽  
Vol 9 (1) ◽  
pp. 6885-6887
Keyword(s):  
Mechanical Properties ◽  
Thermal Conductivity ◽  
Information Technology ◽  
Optical Method ◽  
New Method ◽  
Modern Approach ◽  
Heat Engineering ◽  
Aerated Concrete ◽  
Pore Arrangement ◽  
Cellular Concrete

The article presents the results of studies assessing the structure of cellular concrete using a photo-optical method based on the use of a modern approach from the standpoint of information technology. Based on the photo-optical method, a reverse formulation of the problem is also possible: on the basis of a given percentage of porosity of the material, obtain the most optimal pore arrangement (type of packaging) that meets the specified strength and thermal conductivity of aerated concrete. Having a specific type of image of aerated concrete obtained as a result of modeling, otherwise, a specific type of packing of pores of certain sizes that meets the required (specified) characteristics, then, we can set the technological task of obtaining it.

Optimization of Cellular Concrete Microstructure for Improved Impact Resistance

2021 ◽  
pp. 036119812110263
Author(s):  
Jamie V. Clark ◽  
David A. Lange
Keyword(s):  
Cellular Structure ◽  
Impact Resistance ◽  
Constant Load ◽  
Design Guidelines ◽  
Design Tool ◽  
Low Velocity Impact ◽  
Low Velocity ◽  
Foaming Agents ◽  
Overall Performance ◽  
Cellular Concrete

Engineered material arresting system (EMAS) is a cellular concrete material currently used as passive aircraft arresting system at airports around the U.S.A. and abroad. Its cellular structure crushes on impact, helping to absorb energy and create drag resistance. Energy absorbed during crushing is defined by the load–deformation response curve, in which a plateau is indicative of crushing behavior at a near-constant load. At the microstructural level, the energy absorbed from crushing is a combination of elastic buckling, plastic yield, and brittle fracture of the cellular microstructure. Therefore, optimization of the cellular structure (e.g., bubble size and distribution) is paramount to the overall performance of these systems. This study makes use of microstructural investigations, quasi-static indentation, and drop weight testing to investigate the performance of cellular concrete with varied microstructures. The results show that, while density (air content) has been considered the main predictor of overall performance, the nature of the cellular structure created by the use of different foaming agents can be a useful design tool. This adds another critical consideration in the design of impact-resistant infrastructure. Given this finding, a new set of design guidelines are presented in this paper. This work aims to inform better design of impact-resistant infrastructure by identifying cellular concrete microstructures that lead to optimal energy absorption in low-velocity impact events, such as aircraft overruns.

Processing Methods Used to Create High-Quality Porous Structure of Aerated Concrete

2020 ◽  
Vol 992 ◽  
pp. 212-217
Author(s):  
L.A. Suleymanova ◽  
A.S. Kolomatsky ◽  
M.V. Marushko
Keyword(s):  
Porous Structure ◽  
Structure Formation ◽  
Volume Ratio ◽  
Effect Of Temperature ◽  
Thermal Vacuum ◽  
High Quality ◽  
Molding Sand ◽  
Processing Methods ◽  
Concrete Production ◽  
Aerated Concrete

The efficiency of porous structure formation in aerated concrete can be improved by including the methods of thermal vacuum compaction or thermal vacuum compaction with vibration into the process as a means of creating high-quality composite cellular concrete. A graphic model of a phase composition change in the aerated concrete mix was developed allowing for an evaluation of the recipe and the mode of bubble porosity generation during hardening. This provides a control over the manufacturing processes and helps to produce aerated concrete with the specified porosity balance, which defines product properties.The effect of temperature and vacuum on molding sand during the initial stage of manufacture is proportional to the bubble porosity volume, which is important for a high-quality porous structure formation. In addition to the above, account must be taken of the combined effect of temperature, vacuum and volume ratio of phases in the base mix when using the proposed methods.Introduction of the developed processing methods into the manufacturing process improves the technology of aerated concrete production and allows for a fabrication of the finest advanced heat insulating and structural and heat insulating products.

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