scholarly journals ROLE OF GRANULOMETRY OF MIXED BINDERS IN FORMATION OF THEIR MICROSTRUCTURE AND STRENGTH

2021 ◽  
Vol 6 (7) ◽  
pp. 33-43
Author(s):  
L. Zagorodnyuk ◽  
D.S. Mahortov ◽  
V. Ryzhikh ◽  
D. Sumskoy ◽  
M. Dayronas
Keyword(s):  
Portland Cement ◽  
Volcanic Ash ◽  
Pore Space ◽  
Ash Content ◽  
Cement Stone ◽  
Hydration Products ◽  
Mechanical Mixing ◽  
Mineral Fillers ◽  
Active Interaction

A complex system is formed when grinding Portland cement and various mineral fillers. It consists of grains of various sizes with a predominance of a highly dispersed phase. The work investigates the effect of mixed binders prepared on the basis of Portland cement and volcanic ash at various dosages. The analysis of volcanic ash particles is carried out. It is found that the presence of the smallest fractions in the range from 0.3 to 0.07 microns predicts active interaction in the system and the filling of the pore space with hydration products. It has been established that mixed binders obtained by mechanical mixing (without grinding) with a content of 10% volcanic ash have a strength 13% higher than no addition cement. Mixed binders activated by milling in a vibration mill with a volcanic ash content of 10% are characterized by an increase in compressive strength by 22%, which saves Portland cement by up to 10%. Mixed binders with a volcanic ash content of 20% correspond to the strength of cement free. The results obtained indicate the effectiveness and feasibility of using volcanic ash as a mineral component of mixed binders. The microstructure of a cement stone sample from an activated mixed binder is highly homogeneous, dense intergrown plates of a secondary hydrosilicate structure are clearly visible in the sample cleavage, and crystalline products of pozzolanic reactions between ash particles and cement hydration products are formed on the surfaces of secondary hydrosilicate structures. The purpose of this article is to study the role of granulometry of mixed binders in the formation of their microstructure and strength.

scholarly journals Monitoring of Early and Late Age Hydration Products of Volcanic Ash Blended Cement Paste

Proceedings ◽  
2019 ◽  
Vol 34 (1) ◽  
pp. 9
Author(s):  
Joseph ◽  
Al-Bahar ◽  
Chakkamalayath ◽  
Al-Arbeed ◽  
Rasheed
Keyword(s):  
Portland Cement ◽  
Cement Paste ◽  
Volcanic Ash ◽  
Cement Hydration ◽  
Blended Cement ◽  
Sustainable Construction ◽  
Hydration Products ◽  
N2 Adsorption ◽  
Complete Replacement ◽  
Blended Cement Paste

One of the major concerns of concrete industries is to develop materials that consume less natural virgin resources and energy to make sustainable construction practices. Efforts have been made and even implemented to use the waste/by product materials such as fly ash, slag, silica fume, and natural pozzolana as a partial or complete replacement for Portland cement in concrete mixtures. The deterioration of concrete structures in the existing hot and cold climates of Gulf Cooperation Council countries, along with chloride and sulphate attack, demands the use of pozzolanic materials for concrete construction. Volcanic ash incorporated cement based concretes are known for its better performance in terms of strength and durability in harsh marine environments. Understanding the cement hydration process and characterizing the hydration products in microstructural level is a complex and interdependent process that allows one to design complex mix proportions to produce sustainable concrete materials. In this paper, the early and late age hydration behavior along with micro- and pore structure of cement paste samples prepared with locally available ordinary Portland cement (OPC) and volcanic ash (VA) obtained from Saudi Arabia was monitored using X-ray diffraction (XRD), scanning electron microscopy (SEM), thermogravimetric (TGA) and N2-Adsorption analysis. The hydration progress of cement paste samples with different combinations of OPC and VA (0%, 15%, 25%, and 35%) at a w/c ratio of 0.45 after 14, 28, and 90 days were discussed. The qualitative XRD and SEM of cement paste samples showed no new phases were formed during the course of hydration. The disappearance of portlandite with increase in VA content was due to both pozzolanic effect and dilution effect. This was further confirmed quantitatively by the TGA observations that the samples with VA contain less Ca(OH)2 compared to the control specimens. N2 adsorption experiments after 90 days of curing showed larger hysteresis as the VA content increases. The studies show that the incorporation of volcanic ash certainly contributes to the generation of C-S-H and hence the cement hydration progress, especially in the later ages through pozzolanic reactions. A 15–25 % volcanic ash blended cement paste samples showed compact and denser morphological features, which will be highly detrimental for the durability performances.

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 MICROSTRUCTURE HYDRATION PRODUCTS BINDING COMPOSITION OBTAINED IN THE VORTEX JET MILL

2017 ◽  
Vol 2 (3) ◽  
pp. 9-18 ◽  
Author(s):  
Золотых ◽  
Sergey Zolotykh ◽  
Сумской ◽  
Dmitriy Sumskoy ◽  
Загороднюк ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Portland Cement ◽  
Mechanical Activation ◽  
Cement Stone ◽  
Mineral Filler ◽  
Hydration Products ◽  
Dense Structure ◽  
Additional Support ◽  
Effective Use

Zagorodnuk L.H., Sumy D.A., Golden S.V., Kaneva E.V. MICROSTRUCTURE HYDRATION PRODUCTS BINDING COMPOSITION OBTAINED IN THE VORTEX JET MILL By electron microscopy to study the microstructure of the cement stone made from Portland cement and activated binders of the compositions in the vortex jet mill. It was found that the open pores of the cement and cementitious compositions prepared using perlite fillers, always filled with tumors, at different stages of collective growth. The microstructure of cementitious compositions has a dense structure by rationally selected composition, effective use of mineral filler - perlite waste, creating additional support for the formation of the internal microstructure of the composite, mechanical activation raw mixture, allowing to obtain composites with desired properties.

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.

scholarly journals CEMENT STONE STRUCTURE COMPACTION WITH COMPOSITE BINDER

2019 ◽  
pp. 195-206 ◽  
Author(s):  
R. S. Fediuk ◽  
A. V. Baranov ◽  
D. V. Khromenok ◽  
I. R. Zelenskiy ◽  
S. V. Kim
Keyword(s):  
Portland Cement ◽  
Silicon Dioxide ◽  
Structure Formation ◽  
Quartz Sand ◽  
Strength Properties ◽  
Planetary Mill ◽  
Cement Stone ◽  
Composite Binder ◽  
Silica Additive

The aim of the paper is to improve the strength properties of cement stone via control for structure formation. The composite binder composition includes the type CEM I 42.5N (58–70%) Portland cement, active silica additive (25–37%), quartz sand (2.5–7.5%) and limestone crushed waste (2.5–7.5%). The optimum technology of mechanochemical activation is proposed for the cement stone. The optimization of the structure formation process is provided by the mineral-mineral modifier, crushed together with Portland cement in a planetary mill to a specific surface of 550 m2/kg. The amorphous phase of silicon dioxide in the composition of the modifier intensifies the calcium hydroxide binding forming during alite hydration. It contributes to the growth in low-basic calcium silicate and lowers the cement stone basicity, while reducing the amount of portlandite. The crystalline phase of β-quartz silicon dioxide plays the role of crystallization centers new formations and the cement stone microstructure compaction. Limestone particles contribute to the formation of calcium hydrocarbonate and act as a microfiller together with fine ground quartz sand clogging the pores in the cement stone.

scholarly journals MICROSTRUCTURE HYDRATION PRODUCTS BINDING COMPOSITION OBTAINED IN THE VORTEX JET MILL

2017 ◽  
Vol 2 (3) ◽  
pp. 9-18
Author(s):  
Сергей Золотых ◽  
Sergey Zolotykh ◽  
Дмитрий Сумской ◽  
Dmitriy Sumskoy ◽  
Лилия Загороднюк ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Portland Cement ◽  
Mechanical Activation ◽  
Cement Stone ◽  
Mineral Filler ◽  
Hydration Products ◽  
Dense Structure ◽  
Additional Support ◽  
Effective Use

Zagorodnuk L.H., Sumy D.A., Golden S.V., Kaneva E.V. MICROSTRUCTURE HYDRATION PRODUCTS BINDING COMPOSITION OBTAINED IN THE VORTEX JET MILL By electron microscopy to study the microstructure of the cement stone made from Portland cement and activated binders of the compositions in the vortex jet mill. It was found that the open pores of the cement and cementitious compositions prepared using perlite fillers, always filled with tumors, at different stages of collective growth. The microstructure of cementitious compositions has a dense structure by rationally selected composition, effective use of mineral filler - perlite waste, creating additional support for the formation of the internal microstructure of the composite, mechanical activation raw mixture, allowing to obtain composites with desired properties.

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.

scholarly journals PROCESSES OF CARBONIZING SHRINKAGE OF CONSTRUCTION MATERIALS

2019 ◽  
pp. 178-194
Author(s):  
V. K. Kozlova ◽  
V. A. Lotov ◽  
Yu. S. Sarkisov ◽  
V. V. Logvinenko ◽  
I. A. Rakhmanova ◽  
...  
Keyword(s):  
Carbon Dioxide ◽  
Cement Paste ◽  
Calcium Silicate ◽  
Building Materials ◽  
Solid Phase ◽  
Pore Space ◽  
Construction Materials ◽  
Cement Stone ◽  
Hydration Products ◽  
Wall Structures

Relevance: This paper studies the durability of structures made of various building materials and the effect of carbon dioxide on building materials with a view to reduce its aggressive and destructive effects. Purpose: The aim of the paper is to identify and eliminate the causes of the building material destruction during their carbonization. Materials/Methods: Silicate brick, cement stone and concrete. Research findings: Research is carried out into the destruction of wall structures made of calcium silicate brick and carbon dioxide corrosion of hydration products in calcium silicate brick and cement brick in concrete. It is found that carbonization in hydration products results in their transfer to a denser state which is accompanied by the reduction in the volume of shrinking deformations which cause sometimes the breach and fracture of material. When considering the water/cement system, it is shown that more credible and visible results on shrinkage processes can be obtained through parameters of its volume phase composition which allow controlling the parameters of the structure rearrangement from the initial to final states of the system, i.e. from cement paste to cement brick hardened at different time intervals. It is shown that after 28 days of hardening, the degree of filling the initial pore space with hydration products reaches 67%, while the porosity of cement brick in the final state is 16.5% at the initial composition of the solid phase Fs1 = 0.5; 13.5% at Fs1 = 0.55; 12.8% at Fs1 = 0.6; 11.2% at Fs1 = 0.65 and 0.7-9.0% at Fs1 = 0.7. It follows that shrinkage processes intensify in cement paste with the initial porosity over 40-50 %. It is possible to reduce the negative effect from shrinkage processes via the addition of carbonate-containing mineral additives such as lime rock or dolomite to the cement or lime and sand composition.

scholarly journals Using of Microsilica for Strength Improvement of Fiber Reinforced Cementitious Surface Compounds

2013 ◽  
Vol 2013 ◽  
pp. 1-7
Author(s):  
S. S. Shebl ◽  
Ibrahim S. Khalil ◽  
H. Shoukry
Keyword(s):  
Date Palm ◽  
Fine Sand ◽  
Structural Performance ◽  
Polypropylene Fibers ◽  
Hydration Products ◽  
Fiber Reinforced ◽  
Surface Compounds ◽  
Extension Work ◽  
Strength Improvement

This study represents an extension work to investigate the role of ultra fine sand (UFS) in enhancing the mechanical properties of fiber reinforced cementitious compounds. The micro-structural origins were identified by scanning electron microscope (SEM). About 50% of UFS had a diameter of less than 20 μm. Ordinary Portland Cement (OPC) was partially substituted by UFS at 3, 5, 7 and 10% by weight of binder. It was found that as UFS loadings increase, the flexural, compressive, and tensile strengths increased up to about 5% UFS loading by 12.9, 15.7 and 30.1%, respectively, thereafter, a decrease in these properties was observed. This can be attributed to the pozzolanic effect besides the filling effect of UFS resulting in enhancing the interfacial bonds between the sand grains and hydration products that makes the paste more homogeneous and dense. The effect of both short natural and artificial fiber loadings on the structural performance of compounds was also studied. Loadings of 2%, by weight, of short natural date palm leaves’ midribs fibers (DP) and artificial polypropylene fibers (PP) were added to the 5% UFS blended mix. An increase in both flexural and tensile strength was achieved, while a decrease in the compressive strength was observed.

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