Mechanism of Interaction between Concrete Cement Matrix and Mineral Additive Particles

2020 ◽  
Vol 992 ◽  
pp. 98-103
Author(s):  
S.M. Rakhimbaev ◽  
A.A. Logvinenko ◽  
M.I. Logvinenko
Keyword(s):  
Cement Matrix ◽  
Cement Stone ◽  
Aggressive Interaction ◽  
Granulated Blast Furnace Slag ◽  
Additive Particles ◽  
Mineral Additive ◽  
Calcium Hydrosilicates ◽  
Mechanism Of Interaction ◽  
Internal Strains

A nature of the forces, which act between the concrete cement matrix and entrained mineral particles (ground additives, fine and coarse additives), has been considered. It has been shown that the adhesion between them is attributable to the forces of different nature. The strongest adhesion between the particles of the hydrated binding material and mineral additives occurs, when materials, which react with calcium hydrate of the pore fluid, are used. The latter includes glassy wollastonite, which is part of granulated blast furnace slag. Even at a temperature of 25 °C, an aggressive interaction between them is observed and firm chemical bonds occur. In such case, the dissociation energy of such bonds ranges from 400 to 500 kJ per bond. Between materials, such as crystalline wollastonite and the concrete cement matrix, there is an epitaxial coalescence of its basal surfaces and tobermorite calcium hydrosilicates formed by the interaction of the binder with water. A direct contact is required between the reacting surfaces for such interaction. This is implemented by virtue of the bond, which is attributable to contraction forces resulting from shrinkage strains of the hydrated particles in the concrete cement matrix. Internal strains of the cement that are attributable to contraction, shrinkage, and carbonization of hydrated compounds result in the cement sheath contracting around the aggregate grains and steel reinforcement. Internal strains of the cement stone can be calculated using the Lame equation. We have reviewed the role of the factors, which are most critical for contraction of the cement ring around coarse particles of the aggregate and for stress-strain properties of artificial conglomerates, which have different composition and purpose.

The Increase of Hydration Activity of Portland Cement by Additives of Crystalline Hydrates

2019 ◽  
Vol 974 ◽  
pp. 195-200
Author(s):  
Yury R. Krivoborodov ◽  
Svetlana V. Samchenko
Keyword(s):  
Phase Composition ◽  
Portland Cement ◽  
Cement Hydration ◽  
Bound Water ◽  
Cement Stone ◽  
Pulsation Apparatus ◽  
Rotary Pulsation Apparatus ◽  
Calcium Hydrosilicates ◽  
Crystalline Hydrates

The article presents the results of a study of the effect of synthesized microdisperse additives of crystalline hydrates based on calcium sulfoaluminates on the properties of cement stone. The effectiveness of the use of a rotary pulsation apparatus (RPA) to obtain microdispersed additives is identified. The possibility of accelerating the hardening of cement stone by entering microdispersed additives into its composition is shown. It has been established that in the presence of microdispersed additives of crystalline hydrates in the cement stone, the phase composition of hydrate tumors changes, the amount of calcium hydrosilicates and ettringite increases, the porosity decreases and the strength of the cement stone increases. This provision is confirmed by the increase in the degree of cement hydration, the amount of bound water in all periods of hardening of the stone. It is proposed to use microdisperse additives, which play the role of primers for the crystallization of ettringite and calcium hydrosilicates, to increase the strength of cement stone in the early stages of hardening.

scholarly journals Application of Ceramsite Dust as an Active Pozzolan Additive in the Cement-Based Compositions

2021 ◽  
Vol 1203 (3) ◽  
pp. 032022
Author(s):  
Grigory Yakovlev ◽  
Zarina Saidova ◽  
Anastasiya Gordina ◽  
Natalia Kuzmina ◽  
Yulia Ginchitskaya ◽  
...  
Keyword(s):  
Microstructural Analysis ◽  
Mineralogical Composition ◽  
Waste Recycling ◽  
Mechanical Tests ◽  
Cement Matrix ◽  
Cement Stone ◽  
Structure And Properties ◽  
New Production ◽  
Mineral Additive ◽  
Calcium Aluminosilicate

Abstract Ceramsite (expanded clay) dust is a waste material, obtained in large volumes all over the world as a by-product of ceramsite gravel production. With the development of the construction industry and the ever-growing amount of ceramsite dust disposed in the landfills, the recycling and rational use of this material is becoming a relevant issue. The currently available technologies for the ceramsite waste recycling are very limited, this is why it is necessary to develop a new effective way to involve this waste into the new production. The present research is based on the assumption that ceramsite dust can be applied effectively as an active pozzolanic mineral additive in the cement-based materials. In order to study the composition, structure and properties of the original clay used for the production of ceramsite, as well as the dehydrated clay dust, captured in the dust removing systems of kilns at ceramsite gravel plants, physical and chemical analysis methods were used. Based on the experimental data, the influence of ceramsite dust on the structure and properties of cement compositions was evaluated. Mechanical tests of the samples showed that the introduction of ceramsite dust as an additive in the amount of 3% by the cement weight leads to an increase in compressive strength by 23% in comparison with the reference composition. The paper also presents the results of microstructural analysis, IR spectral analysis and differential thermal analysis of samples modified with the optimal amount of this microadditive. The study of the microstructure of the modified samples shows that the introduction of ceramsite dust into the composition of the cement stone does not only change the morphology of new formations, thus increasing the density of the structure, but also varies the mineralogical composition of the cement matrix with the formation of stronger and more water-resistant minerals in the form of calcium silicate hydrates and calcium aluminosilicate hydrates. This technology allows the recycling of waste from the production of ceramsite stone, thus improving the environmental situation and contributing to the creation of a circular economy.

scholarly journals Properties of Concretes Incorporating Recycling Waste and Corrosion Susceptibility of Reinforcing Steel Bars

Materials ◽  
2021 ◽  
Vol 14 (10) ◽  
pp. 2638
Author(s):  
Zinoviy Blikharskyy ◽  
Khrystyna Sobol ◽  
Taras Markiv ◽  
Jacek Selejdak
Keyword(s):  
Compressive Strength ◽  
Cement Matrix ◽  
Strength Development ◽  
Reinforcing Steel ◽  
Freezing And Thawing ◽  
Paper Properties ◽  
Granulated Blast Furnace Slag ◽  
Steel Bars ◽  
Calcium Hydrosilicates ◽  
Corrosion Susceptibility

In this paper, properties of concretes incorporating recycling waste and corrosion susceptibility of reinforcing steel bars were studied. It was established that fineness of ground granulated blast furnace slag (GGBFS) and fly ash (FA) and their simultaneous combination have an influence on the kinetics of strength development of Portland cements and concretes. The compressive strength of concrete containing 10% by mass of GGBFS and 10% by mass of FA even exceeds the compressive strength of control concrete by 6.5% and concrete containing 20% by mass of GGBFS by 8.8% after 56 days of hardening. The formation of the extra amount of ettringite, calcium hydrosilicates as well as hydroaluminosilicates causes tightening of a cement matrix of concrete, reducing its water absorption, and improving its resistance to freezing and thawing damage.

scholarly journals A Study of the Potential Use of Red Mud to Obtain Compositions Based on Portland Cement

2020 ◽  
Author(s):  
Ekaterina Gerasimova ◽  
Elizaveta Gumirova
Keyword(s):  
Portland Cement ◽  
Red Mud ◽  
Waste Product ◽  
Cement Stone ◽  
Mathematical Planning ◽  
Alumina Production ◽  
Mineral Additive ◽  
Composition Properties ◽  
Planning Of Experiments ◽  
Potential Use

The paper deals with the problem of utilization of red mud which is a waste product from alumina production using the Bayer method. The principal possible use for the red mud of JSC “Bogoslovsky aluminum plant” (Sverdlovsk region) for the compositions based on Portland cement is shown. It was found that the mud introduction accelerates beginning of the cement paste setting and thickens the paste reducing its mobility. It is concluded that the introduction of red mud up to 30 % is justified in terms of strength indicators. The work is carried out using mathematical planning of experiments. Keywords: red mud, Portland cement, active mineral additive, composition, properties, bauxite, chemical composition, cement stone strength, mathematical planning of experiments

Cement Composites’ Biostability

2020 ◽  
Vol 1011 ◽  
pp. 171-178
Author(s):  
Alexander Rodin ◽  
Sergej Karpushin ◽  
Vasiliy Smirnov
Keyword(s):  
Species Composition ◽  
Sodium Sulfate ◽  
Sampling Methods ◽  
Sea Water ◽  
Cement Clinker ◽  
Cement Stone ◽  
Cement Composites ◽  
Portland Cement Clinker ◽  
Mineral Additive ◽  
Surface Modified

The studies to establish the species composition of micro-mycetes inhabiting the surface of cement composites after aging in sea water have been carried out. Cement stone made on the basis of Portland cement clinker, a mineral additive and a fungicidal preparation was considered as the studied material. To determine the materials’ fouling by microorganisms, their species composition, imprints and sampling methods were used. A change in the species composition of mycobiota isolated from the cement composites’ surface modified with sodium sulfate and sodium fluoride depending on the amount of active filler, gypsum, and biocidal additives was experimentally revealed. The effectiveness of using the biocidal cement composites with an active mineral additive has been confirmed. It was found that the composites on the developed compositions showed higher resistance compared to the materials on ordinary cement. The compositions modified with biocidal additives showed a fungicidal effect.

scholarly journals Sustainable low-carbon binders and concretes

2020 ◽  
Vol 166 ◽  
pp. 06007
Author(s):  
Myroslav Sanytsky ◽  
Tetiana Kropyvnytska ◽  
Stanislav Fic ◽  
Hanna Ivashchyshyn
Keyword(s):  
Activity Index ◽  
Chemical Properties ◽  
High Volume ◽  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Cement Matrix ◽  
Low Carbon ◽  
Blended Cements ◽  
Physical And Chemical

Sustainable development depends on a consistency of interests, social, ecological and economic, and that the interests are evaluated in a balanced manner. In order to reduce CO2 emissions, the conception of decreasing clinker factor and increasing the role of supplementary cementitious materials (SCMs) in the cementitious materials has high economical and environmental efficiency. The performance of clinkerefficient blended cements with supplementary cementitious materials were examined. The influence of superfine zeolite with increased surface energy on the physical and chemical properties of low-carbon blended cements is shown. Increasing the dispersion of cementitious materials contributes to the growth of their strength activity index due to compaction of cement matrix and pozzolanic reactions in unclincker part. In consequence of the early structure formation and the directed formation of the microstructure of the cement matrix is solving the problem of obtaining clinker-efficient concretes. Shown that low-carbon blended cements with high volume of SCMs are suitable, in principle, for producing structural concretes.

The Study of Cement Concrete with Improved Properties Based on the Use of Astivated Silica Fume

2020 ◽  
Vol 992 ◽  
pp. 228-232
Author(s):  
E. Tkach ◽  
V. Soloviev ◽  
R. Temirkanov ◽  
Denis B. Solovev
Keyword(s):  
Large Scale ◽  
Positive Influence ◽  
Cement Stone ◽  
Chemical Characteristics ◽  
Structure Modification ◽  
Cement Concrete ◽  
Modification Process ◽  
Physico Chemical ◽  
Scale Levels

In this research the questions of microsilica usage and ways of its activation for modification of structure of cement stone and cement on its basis. The actual questions corresponding any type of filler, particularly microsilica are: how and how much should be put, which mechanisms are involving to process of structuring, how much is received result of structure modification and others. Therefore the role of microdispersed fillers in modification process of cement rock and cement on its basis must be viewed in connection with other dimensional inclusions on different large-scale levels. Reducing of concrete consumption by its substitution by microsilica, has a positive influence to physico-chemical characteristics of concrete.

scholarly journals Influence of optimal conditions of ultrasonic dispersion on the stability of suspensions of finely ground slags

2019 ◽  
Vol 265 ◽  
pp. 01017 ◽  
Author(s):  
Svetlana Samchenko ◽  
Irina Kozlova ◽  
Оlga Zemskova ◽  
Ekaterina Baskakova
Keyword(s):  
Aqueous Dispersion ◽  
Cement Composite ◽  
Cement Stone ◽  
Mechanical Mixing ◽  
Dispersion Parameters ◽  
Ultrasonic Dispersion ◽  
Sedimentation Stability ◽  
Granulated Blast Furnace Slag ◽  
The Stability ◽  
Furnace Slag

The preparation in the jet mill of finely ground slag (FGS) from the waste of metallurgical production granulated blast-furnace slag, the obtaining of slag suspensions, and the behavior of FGS particles in an aqueous dispersion medium are considered in the paper. It was found that FGS particles in the suspension form micelles of two types with negative (micelle 1) and positive (micelle 2) charges of FGS surface. To increase the aggregative and sedimentation stability of FGS particles in suspensions, studies were carried out using ultrasonic dispersion. The results of investigations on the detection of optimal dispersion parameters for slag suspensions are presented. It was found that in the absence of temperature control, the process of coagulation of slag particles is accelerated and aggregative and sedimentation stability of suspensions of FGS is reduced. The slag particles in the suspension form aggregates that lead to a deterioration of the strength characteristics of the cement stone using suspensions of FGS. Optimal parameters of ultrasonic dispersion of slag suspensions are established: the frequency of ultrasonic vibrations is equal to 44 kHz; the dispersion temperature is 25 ± 2 °C; the dispersion time is 15 min. It was found that the application of ultrasonic dispersion to slag suspensions with the observance of dispersion conditions can increase the aggregative and sedimentation stability of FGS suspension by 2-3 times in comparison with the mechanical mixing of suspensions. The strength of samples with suspensions of FGS prepared using UST under the recommended dispersing conditions increased by 19 to 39% in the first day; for 28 days of hardening - by 19 - 36%, which allows using slag suspensions in the production of cement composite materials and concretes based on them.

An Experimental Study of Pig Blood–Lime Mortar Used on Ancient Architecture in China

2014 ◽  
Vol 997 ◽  
pp. 496-499 ◽  
Author(s):  
Peng Zhao ◽  
De Qing Xie ◽  
Guang Yan Li ◽  
Yun Sheng Zhang
Keyword(s):  
Building Materials ◽  
Early Stage ◽  
Architectural History ◽  
Environmental Scanning Electron Microscopy ◽  
Environmental Scanning ◽  
Historical Buildings ◽  
Lime Mortar ◽  
Mechanism Of Interaction ◽  
Scanning Electron

Portland cement has low chemical and physical affinity for traditional building materials. This hinders the restoration of historical buildings and modern rustic architecture where blue bricks are used. Pig blood–lime mortar is one of the most important technological inventions in the Chinese architectural history. Mortar in this work was fabricated according to formulas of the literature, and some analyses were conducted for further understanding their microstructure. Environmental scanning electron microscopy was utilized to analyze mechanism of interaction between key components of ancient mortar bonding materials. Results show that pig blood accelerates the formation of microstructure at early stage. Pig blood plays the role of biological templates which regulates the growth of calcium carbonate crystal.

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