Influence of Nanoscale Barium Hydrosilicates on Composition of Cement Stone

2016 ◽  
Vol 683 ◽  
pp. 90-94 ◽  
Author(s):  
Anna Nikolaevna Grishina ◽  
Evgeniy Valerjevich Korolev
Keyword(s):  
Composite Materials ◽  
Chemical Composition ◽  
Portland Cement ◽  
Cement Hydration ◽  
Experimental Investigations ◽  
Cement Stone ◽  
Hydration Products ◽  
Efficient Control ◽  
Calcium Hydrosilicates ◽  
Portland Cement Hydration

The development of new types of composite materials is an important aim for construction. Nanoscale admixtures allow efficient control of the composition and properties. Results of experimental investigations concerning effect of admixture of nanoscale barium hydrosilicates to the chemical composition of hydrated portland cement are discussed in the present work. It is shown that several key processes are taking place during nanomodification. Amount of portlandite in cement stone decreases, and there is also quantity growth of different calcium hydrosilicates CSH (I), CSH (II), riversideite and xonotlite. Influence of composition and storing time of barium hydrosilicates to the ratio of different portland cement hydration products is examined. It is found that admixture of barium hydrosilicates with gross formula BaO•26.47SiO2•nH2O stored for 28 days leads to both reduction of portlandite and accretion of hydrated phase.

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 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.

Improvement of Wood-Cement Composition Properties with Microsilica Additive

2020 ◽  
Vol 992 ◽  
pp. 162-167
Author(s):  
E.Yu. Gornostaeva ◽  
N.P. Lukuttsova ◽  
D.I. Dryazgov
Keyword(s):  
Thermal Conductivity ◽  
Compressive Strength ◽  
Silicon Dioxide ◽  
Cement Hydration ◽  
Cement Stone ◽  
Hydration Products ◽  
Maximum Increase ◽  
Calcium Hydrosilicates ◽  
Calcium Silicates ◽  
Composition Properties

The properties and microstructure of wood-cement compositions (WCC) with microsilica (MS) additive for the manufacture of small-pieces wall products are studied. The extreme dependences of mean density, thermal conductivity and compressive strength on the content of microsilica additive are established. The mechanism of microsilica effect on wood-cement compositions is offered. Two interrelated factors (chemical and physical) could be distinguished at that. The first factor includes mainly the interaction of silicon dioxide with lime having released during hydration of calcium silicates, i.e. pozzolatic process. The second factor lies in the compaction of wood-cement compositions and the cement stone structure by means of cement hydration products and silica particles. It is established that introducing 20% of microsilica in the composition results in the maximum increase in ultimate compression strength (3 times). It can be explained not only by forming calcium hydrosilicates, uniformly and densely covering the wood aggregate, but by compacting effect of spherical microsilica inclusions, filling the space between the new cement stone formations and wood aggregate.

scholarly journals Ultrafast transfer strength of reinforced concrete sleepers by Using complex additives

2021 ◽  
pp. 44-63
Author(s):  
Andrii Plugin ◽  
Olena Kaliuzhna ◽  
Olga Borziak ◽  
Oleksii Plugin ◽  
Oleksandr Savchenko
Keyword(s):  
Energy Intensity ◽  
Cement Hydration ◽  
Experimental Investigations ◽  
Cement Stone ◽  
Hydration Products ◽  
Heat Regime ◽  
Electron Microscopic ◽  
Initial Stage ◽  
Early Strength ◽  
Mineral Additives

The influence of superplasticizers-polycarboxylates and their complex additives withaccelerants - electrolytes and dispersion of calcium hydroxylates on the early strength of concretefor concrete of concrete sleepers has been studied. It was found that the use of superplasticizerspolycarboxylates can improve the early strength of the concrete after heat treatment, but eachadditive must be checked for consistency with the cement used. Approx Complex additives withaccelerators in conditions of natural hardening ensure an increase in the early strength of concrete,but some of them, which accelerate natural hardening, can reduce the strength after WWTP and mustbe checked before use. Electron-microscopic examinations of the structure of cement stone withadditives were carried out and it was found that the additive of only policarboxylate does not changethe structure of hydration products. Complex additives lead to formation of additional number ofcrystalline hydrates of AFm- and/or AFt-phases. The scheme of development of the cement hardeningprocess and the initial stage of cement hardening without or with additives has been developed. Bymeans of which the highest accelerating effect of the complex addition of polycarboxylate andcalcium hydroxylate dispersions was established by experimental investigations, Dispersion particlesincrease surface area where crystallization (condensation) of cement hydration products takes placeand ensures faster filling of spaces between cement particles (mineral additives) with them, fillers)with establishment of lances with electro-heterogeneous contacts. As a result of potentiodynamic andmicroscopic investigations it was established that the tested additives in the dosages do not causecorrosion effect on the steel reinforcement bars. Transmission strength values of 32 MPa for sleepersafter 24 years of hardening under low-heat regime and after 2 days of natural hardening have beenachieved. The formula for economic efficiency of using additives to reduce the energy intensity ofproduction of concrete sleepers has been proposed.

The Structural Formation of Cement Stone Modified by a Solution of Superabsorbent Polymer

2022 ◽  
Vol 906 ◽  
pp. 59-67
Author(s):  
Alexandr Sergeevich Inozemtcev ◽  
Evgenij Korolev ◽  
Duong Thanh Qui
Keyword(s):  
Portland Cement ◽  
Structure Formation ◽  
Water Loss ◽  
Cement Hydration ◽  
Cement Stone ◽  
Layer By Layer ◽  
Superabsorbent Polymer ◽  
Hydration Products ◽  
Structural Formation ◽  
Strength And Durability

With the development of 3D technologies in construction, the development of formulations that are indifferent to the influence of the environment is in demand. Conditions of intense water loss from cement systems arise during the layer-by-layer printing process. This leads to a decrease in density, high shrinkage, and a decrease in the strength and durability of the composite. The use of superabsorbent polymer (SAP) solutions, in contrast to granules, will provide hardening Portland cement with a water supply for internal care of hydration processes. The aim of the work is to study the effect of SAP solution on the processes of structure formation of cement stone, hardening in unfavorable conditions. In this paper, the features of the structure formation of cement systems in the presence of SAP are established. It is shown that the use of polymer in an amount of no more than 1.5% by the weight of Portland cement provides the formation of a more perfect crystalline structure of the cement stone, which allows for an increase in the degree of cement hydration. When the amount of SAP is ≥ 1.5% by the weight of Portland cement, a decrease in the intensity of the maxima corresponding to hydration products is observed.

EFFECT OF VISCOSITY MODIFIER ADMIXTURE ON PORTLAND CEMENT HYDRATION

2018 ◽  
Author(s):  
Stefan C. Figueiredo ◽  
Oğuzhan Çopuroğlu ◽  
Erik Schlangen
Keyword(s):  
Portland Cement ◽  
Cement Hydration ◽  
Viscosity Modifier ◽  
Portland Cement Hydration
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