scholarly journals Development of alkaline concrete on the basis of active aggregates

2021 ◽  
Vol 6 (1(62)) ◽  
pp. 36-42
Author(s):  
Oleksandr Kovalchuk ◽  
Viktoriia Zozulynets
Keyword(s):  
Structure Formation ◽  
Building Materials ◽  
Component Composition ◽  
The Body ◽  
Cement Stone ◽  
Deformation Properties ◽  
The Matrix ◽  
Mineral Additive ◽  
Alkaline Component ◽  
Alkaline Corrosion

The object of the research is the process of directed structure formation in the body of alkaline concrete, made using a reactive aggregate, in this case, basalt, and the process of deformation development in such concrete. The problem with using reactive aggregates is that they cause alkaline corrosion. It manifests itself in the form of cracks and layers of gel-like substances that form at the point of contact of the aggregate with the cement stone. During the research, methods of physical and chemical analysis were used (X-ray phase, differential thermal and thermogravimetric analyzes, electron microscopy, infrared spectroscopy, microprobe analysis). And also methods of mathematical planning of experiments have been used for the dependence of the physical and technical properties of cements and the directions of their structure formation. Also, the research has been carried out based on the analysis of world achievements in solving the problem of alkaline corrosion of concrete. The possibility of joint operation of the matrix of alkaline cements and active aggregates, represented by basalt, has been determined. The component composition of alkaline cement has been optimized and the need to increase the amount of the alkaline component in the system for the normal course of structure formation processes has been proved. The study of the influence of technical factors and conditions of hardening on the development of processes of structure formation of the investigated compositions has been carried out. The deformation properties of fine-grained concrete based on slag-alkaline cement and basalt aggregate have been investigated. It is shown that the expansion deformations of the samples, which accompany the process of alkaline corrosion of the aggregate in concrete, are directly related to the component composition and hardening conditions of the material. The obtained research results confirm the possibility of using active aggregates for the manufacture of building materials, in particular, based on alkaline cements. But for the safe course of the processes of structure formation, the component composition of the system has to be adjusted by introducing an active mineral additive and an additional alkaline component. The use of hydrophobizing additives makes it possible to increase the strength of the material even when operating under normal heat and humidity conditions.

scholarly journals STUDY OF DEFORMATION PROPERTIES OF ALKALI ACTIVATED CONCRETES USING ACTIVE AGGREGATES

2021 ◽  
pp. 69-77
Author(s):  
O.Yu. Kovalchuk ◽  
◽  
V.V. Zozulynets ◽  
Keyword(s):  
Component Composition ◽  
Mineral Admixture ◽  
Fine Grain ◽  
Soluble Glass ◽  
Deformation Properties ◽  
Alkaline Component ◽  
Destructive Processes ◽  
Alkaline Corrosion ◽  
Time Linear ◽  
Alkali Activated

Abstract. Results of study of deformative properties of fine-grain concrete are shown using slag alkali activated cement and active aggregate, represented by fraction 0-2.5 mm. It had been shown that expansion deformations of concrete specimens, supplying process of alkaline corrosion of aggregate in concrete, directly combined with component composition and conditions of hardening and storing of material. Thus, it was show, that using alkaline component in the state of dry salt (sodium carbonate) shrinkage/expansion deformations are varying in the shorter ranges comparing to alkali activated concrete with the alkaline component represented by soluble glass. Introduction of active mineral admixture represented by metakaolin also leads to the decreasing of deformations comparing to the compositions without such admixture. Different conditions of hardening and storing of the specimens are also influence well on the development of shrinkage deformations. It is shown that drying of specimens with active process of alkaline corrosion of concrete makes it possible to stop development of expansion deformations in concrete. Hydrophobization of the dried specimens make it possible to store for some time linear characteristics of concrete specimens. This opens the possibility to store lifeability and exploitation terms of construction with destructive corrosion processes in concrete without spending significant costs and without canceling of construction exploitation. Hydrophobization of specimens without drying leads to the intensification of structure formation processes and higher rates of development of shrinkage/expansion deformations. That means, that traditional method of protection of concrete constructions (covering of concrete constructions by painting materials) is not able to prevent, but also possible to activate development of destructive processes of alkaline corrosion of concrete, becoming dangerous to be used.

scholarly journals Nano-level management of calcium silicate-hydrate nanoparticles structure formation during portland cement hydration process

2018 ◽  
Vol 196 ◽  
pp. 04012
Author(s):  
Alexander Guryanov ◽  
Vyacheslav Kozlov ◽  
Yulia Sidorenko
Keyword(s):  
Portland Cement ◽  
Structure Formation ◽  
Building Materials ◽  
Cement Hydration ◽  
Structural Parameters ◽  
Control Process ◽  
Hydration Process ◽  
Cement Stone ◽  
Carbonate Sludge ◽  
Portland Cement Hydration

Cement-containing building materials durability depends both on the original clinker composition and on the structure of hydrated portland cement compositions on micro and nanoscales. To calculate structural parameters of silicate-hydrate calcium nanoparticles during portland cement hydration process, the researchers applied the method of small-angle neutron scattering which included distribution of nanoparticles in size, medium nanoparticles radius, fractal dimension. Modifying nanoparticles blending with portland cement composition affects structural parameters of silicate-hydrate calcium nanoparticles. The authors used complex modifying nanoparticles in this study. Nanoparticle composition included a component that served as a filler and a chemically active component that was used as a modifier. The first component was a mixture of alpha oxide aluminum, gamma oxide aluminum and carbonate sludge. The second component presented a mixture of alumoalkaline sludge with alumocalcite sludge. These sludges were of technogenic origin. The research showed that application of complex nanoagents made it possible to control process of silicate-hydrate calcium nanoparticles structure formation, and, as the result, to influence durability of cement stone.

scholarly journals INFLUENCE OF THE SCOPE ADDITION ON THE STRUCTURE FORMATION OF THE CEMENT STONE BY THE METHOD OF QUANTITATIVE X-RAY PHASE ANALYSIS

2019 ◽  
Vol 16 (4) ◽  
pp. 504-518
Author(s):  
I. L. Chulkova ◽  
I. A. Selivanov ◽  
V. D. Galdina
Keyword(s):  
Portland Cement ◽  
Structure Formation ◽  
Phase Analysis ◽  
Mineral Composition ◽  
Large Scale ◽  
Building Materials ◽  
Cement Matrix ◽  
Cement Stone ◽  
X Ray ◽  
Mineral Compositions

Introduction. The processes of structure formation of cement compositions and the development of effective technologies of building materials is an urgent task for building material science. The use of large-scale man-made product of pulp and paper enterprises – osprey as a fibrous filler in organic and mineral compositions is the successful decision of the problem. The paper analyzes the ways of using osprey in the building materials’ production. The aim of the research is to study the osprey influence on the processes of structure formation of cement stone by quantitative x-ray phase analysis.Materials and methods. The organic and mineral compositions were obtained on the basis of portland cement and osprey. The authors studied the compositions’ phase of osprey, portland cement and the processes of cement stone structure formation in organ and mineral compositions by quantitative x-ray phase analysis.Results. The authors determined the compositions’ phase of mineral impurities of osprey, cellulose, cement, cement stone, organic and mineral compositions and two compositions containing 25 and 75% by weight.Discussion and conclusions. The osprey application as a filler in the organic and mineral composition causes inhibition of processes of cement hydration. The presence of osprey in the hardening organic and mineral composition leads to a change in the composition and structure of the cement stone in comparison with the phase composition of the cement stone without additives. The result of these changes is a significant increase in the amount of calcite, waterite and a significant decrease in the amount of portland. The authors establish that the effective joint work of the reinforcing component of the osprey with the cement matrix is possible with a limited amount of osprey in organic and mineral compositions.

scholarly journals A mechanism of Portland cement hardening in the presence of finely grained glass powder

2007 ◽  
Vol 1 (3) ◽  
pp. 179-184
Author(s):  
Victor Shevchenko ◽  
◽  
Wojciech Swierad ◽  
Keyword(s):  
Portland Cement ◽  
Structure Formation ◽  
Building Materials ◽  
Glass Powder ◽  
Cement Stone ◽  
Developed Surface ◽  
Glass Wastes ◽  
Chemical Influence

The glass wastes as a cullet are widely used for the production of building materials mainly as inert aggregate. However finely grained glass powder has the very developed surface, so can not be passive toward cement solutions, what was confirmed in practice. In literature data there is no information about chemical influence of finely grained glass on the process of hardening, especially in an early pre-induction hydration period, which substantially causes the structure formation of cement stone and its properties.

Effect of Granulometric Component Composition in Cellular Concrete on Cement Consumption Rate

2019 ◽  
Vol 945 ◽  
pp. 76-79 ◽  
Author(s):  
L.M. Vesova
Keyword(s):  
Building Materials ◽  
Mineralogical Composition ◽  
Component Composition ◽  
Industrial Wastes ◽  
Raw Material ◽  
Cement Matrix ◽  
Material Base ◽  
Mineral Additive ◽  
Partition Structure ◽  
Cellular Concrete

The use of local natural and technogenic raw materialsallows expansion of the raw material base for producing the building materials and reduction of production cost. Creation of low energy-intensive technologies for producing the building materials is a priority for the construction industry. The chemical and mineralogical composition of industrial wastes makes it possible to use them for producing the low-clinker or clinker-free composite binders. Secondary resources can be used as an active mineral additive that would allow to reduce the cement consumption. The properties of cellular concrete depend on the formed cement matrix structure, the strength of the inter-pore partitions. Quality can be managed by directional formation of the mechanical framework. Providing the necessary granulometric composition of the cellular concrete components is decisive for the mechanical framework formation. The inter-pore partition structure in the cellular concrete is a developed silicate matrix formed by hydration products and a siliceous component. Therefore, when designing this structure, an analogy with ordinary dense concrete is quite possible. The basic principle for designing the concrete composition consists in creating a dense packaging of the constituent components.

scholarly journals FEATURES OF THE STRUCTURE OF NEW GENERATION CONCRETE WITH THE USAGE OF ARTIFICIALLY-PRODUCED MATERIALS

2018 ◽  
Vol 15 (4) ◽  
pp. 588-595 ◽  
Author(s):  
A. D. Tolstoy ◽  
V. S. Lesovik ◽  
A. S. Milkina
Keyword(s):  
Structure Formation ◽  
Building Materials ◽  
Raw Materials ◽  
Experimental Studies ◽  
Construction Materials ◽  
High Strength ◽  
Standard Test ◽  
Cement Stone ◽  
Organic Additives ◽  
Test Procedures

Introduction. The important national economic task is to provide the modern construction industry with high-strength and effective materials made using new technological approaches and artificiallyproduced materials. These materials differ from the usual one by high content of cement stone, smaller grain size, multicomponent composition, increased specific surface of the filler. Therefore, the research of such problem would be always relevant according to the constant growth of requirements for the building materials and structures quality.Materials and methods. Experimental studies were conducted in the laboratories of the Department of Construction Materials, Products and Structures. The literary sources’ analysis was made in the scientific and technical library of the Belgorod State Technological University named after V. G. Shukhov. At the same time, standard test procedures and the provisions of the operating instructions for individual devices and equipment were used in the research.Discussion and conclusions. As a result, the models of structure formation in high-strength hardening compositions, in which the principle of structure optimization consisting in creation of the high degree ordering of its constituent elements and tumors, as well as in increasing the adhesion of cement stone particles, are implemented. In addition, the usage of artificially-produced materials and organic additives produces the possibility of reducing the consumption of raw materials and consumption of energy and resources. The mechanism and principles of structure formation management are intensively studied and would be explained later on the basis of synergetic concepts.

Study Of Structure Formation Of Organic-Mineral Compositions With Fibrous Filler By Electron Microscopy Method

2019 ◽  
pp. 41-47
Keyword(s):  
Electron Microscopy ◽  
Structure Formation ◽  
Mineral Composition ◽  
Bending Strength ◽  
Cement Stone ◽  
Hydrated Cement ◽  
Fibrous Filler ◽  
Organic Mineral ◽  
Microscopy Method ◽  
Mineral Compositions

The article presents the study of processes of structure formation of cement stone and products of hardening of organic-mineral compositions with fibrous filler (shavings) by the electronic scanning microscopy method. It is established that the additive-free cement stone at the age of 28 days has a dense and homogeneous structure, consists of calcium hydro-silicates, Portlandite and calcite - newgrowths characteristic for cement systems. Cellulose fibers, which make up the bulk of the substance of shavings, are sufficiently active, which determines the high adhesion of the hydration products of the cement binder to their surface. It is shown that the introduction of shavings into the organo-mineral composition leads to inhibition of cement hydration processes. Organo-mineral compositions with different shavings content (two compositions) were analyzed. The first composition is characterized by a fairly dense structure, the cement stone consists of globular nanoscale nuclei of hydrosilicates, Portlandite and calcite. The second composition has a loose porous structure, cement stone consists of non-hydrated cement grains, newgrowths are represented by calcite and vaterite. The structure of the contact zone "osprey fiber-cement stone" in the organo-mineral composition of the first composition indicates a good adhesion of the filler surface with the phases of hydrated cement. The use of shavings as a fibrous filler (the first composition) increases the tensile and bending strength, as well as the wear resistance of organo-mineral compositions. The data obtained by scanning electron microscopy are confirmed by the results of studying the processes of structure formation of cement stone by quantitative x-ray phase analysis.

scholarly journals The Dimension of the Body in Higher Education: Matrix of Meanings in Students’ Diaries

Human Arenas ◽  
2021 ◽  
Author(s):  
Ramiro Tau ◽  
Laure Kloetzer ◽  
Simon Henein
Keyword(s):  
Higher Education ◽  
Performing Arts ◽  
Teaching And Learning ◽  
Educational Practice ◽  
The Body ◽  
Cultural Perspective ◽  
General Process ◽  
Emotional Dimension ◽  
The Matrix ◽  
The Mind

AbstractIn this paper, we attempt to show some consequences of bringing the body back into higher education, through the use of performing arts in the curricular context of scientific programs. We start by arguing that dominant traditions in higher education reproduced the mind-body dualism that shaped the social matrix of meanings on knowledge transmission. We highlight the limits of the modern disembodied and decontextualized reason and suggest that, considering the students’ and teachers’ bodies as non-relevant aspects, or even obstacles, leads to the invisibilization of fundamental aspects involved in teaching and learning processes. We thus conducted a study, from a socio-cultural perspective, in which we analyse the emerging matrix of meanings given to the body and bodily engagement by students, through a systematic qualitative analysis of 47 personal diaries. We structured the results and the discussion around five interpretative axes: (1) the production of diaries enables historicization, while the richness of bodily experience expands the boundaries of diaries into non-textual modalities; (2) curricular context modulates the emergent meanings of the body; (3) physical and symbolic spaces guide the matrix of bodily meanings; (4) the bodily dimension of the courses facilitates the emergence of an emotional dimension to get in touch with others and to register one's own emotional experiences; and (5) the body functions as a condition for biographical continuity. These axes are discussed under the light of the general process of consciousness-raising and resignification of the situated body in the educational practice.

scholarly journals The Influence of Cement Substitution by Biomass Fly Ash on the Polymer–Cement Composites Properties

Materials ◽  
2021 ◽  
Vol 14 (11) ◽  
pp. 3079
Author(s):  
Beata Jaworska ◽  
Dominika Stańczak ◽  
Joanna Tarańska ◽  
Jerzy Jaworski
Keyword(s):  
Fly Ash ◽  
Building Materials ◽  
Raw Materials ◽  
Combustion Process ◽  
Biomass Combustion ◽  
Cement Composites ◽  
Cement Mortars ◽  
Mineral Additive ◽  
Biomass Fly Ash

The generation of energy for the needs of the population is currently a problem. In consideration of that, the biomass combustion process has started to be implemented as a new source of energy. The dynamic increase in the use of biomass for energy generation also resulted in the formation of waste in the form of fly ash. This paper presents an efficient way to manage this troublesome material in the polymer–cement composites (PCC), which have investigated to a lesser extent. The research outlined in this article consists of the characterization of biomass fly ash (BFA) as well as PCC containing this waste. The characteristics of PCC with BFA after 3, 7, 14, and 28 days of curing were analyzed. Our main findings are that biomass fly ash is suitable as a mineral additive in polymer–cement composites. The most interesting result is that the addition of biomass fly ash did not affect the rheological properties of the polymer–cement mortars, but it especially influenced its compressive strength. Most importantly, our findings can help prevent this byproduct from being placed in landfills, prevent the mining of new raw materials, and promote the manufacture of durable building materials.

Small angle reconstruction of plasma luminosity for spherical tokamak

2020 ◽  
Author(s):  
А.Н. Баженов ◽  
П.А. Затылкин
Keyword(s):  
Power Plants ◽  
Essential Feature ◽  
Real Data ◽  
The Body ◽  
Magnetic Sensors ◽  
Test Problems ◽  
General View ◽  
Central Projection ◽  
The Matrix ◽  
Matrix Detector

Публикация посвящена применению методов вычислительной геометрии, интервального анализа и линейного программирования к задачам физики управляемого термоядерного синтеза. Рассмотрены геометрические аспекты проблемы, получены проекции светимостей различных объемов сферического токамака на плоскость матричного детектора, изучены изображения предполагаемых макроскопических структур и микроскопических включений. Для набора модельных распределений светимости объема токамака поставлена задача восстановления сигнала. Решение получено с использованием задач линейного программирования. The problems of reconstruction of plasma luminosity are important for physics and technology of power plants-tokamaks. The Globus-M research tokamak obtained a large amount of data using a matrix detector in pinhole camera geometry. From the mathematical point of view, finding the luminosity for different regions of the plasma volume according to the matrix detector is an inverse problem related to the field of integral geometry. An essential feature of the particular task is the use of a single fixed camera with a small viewing angle. In this regard, application of methods of harmonic analysis of data is not enough. The paper investigates the geometric aspects of the problem. In the general view, a threedimensional object is projected onto a two-dimensional plane through a diaphragm. Under the assumption of azimuthal symmetry, there is a central projection of the luminosity of the body of rotation onto a flat matrix detector. The initial information for the calculation is the plasma boundary obtained from magnetic sensors. There is no reliable information about the internal structure of the plasma, so its division into regions of the equal luminosity is not unambiguous. The paper presents an algorithm for finding the projections of the luminosity of plasma volumes on the plane of the matrix detector. A set of model direct problems for the construction of algorithms for their recognition according to the detector data was investigated. Images of supposed macroscopic structures and microscopic inclusions were obtained. The methodological basis of the work is the use of interval analysis methods for solving geometric and algebraic problems. This approach allows obtaining qualitative and quantitative results that takes into account the uncertainty of the input data with the minimum amount of computational costs. Algebraic solvability is investigated in the interval formulation using response functionality. Solutions for a set of test problems are obtained, which demonstrate the availability of successful reconstruction for real data. An important result of the study is an information about the presence of uncertainties in geometric data and related calculations by obtaining results about the luminosity of the plasma by solving linear programming problems.

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