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.

scholarly journals Increase of aggregative and sedimentation stability of slag suspensions by ultrasound

2019 ◽  
Vol 110 ◽  
pp. 01061
Author(s):  
Svetlana Samchenko ◽  
Irina Kozlova ◽  
Оlga Zemskova ◽  
Ekaterina Baskakova
Keyword(s):  
Building Materials ◽  
Aqueous Dispersion ◽  
Micelle Formation ◽  
Cement Matrix ◽  
Aggregative Stability ◽  
Mechanical Mixing ◽  
Dispersion Parameters ◽  
Ultrasonic Dispersion ◽  
Sedimentation Stability ◽  
Object A

The paper discusses the relevance of the use of metallurgical wastes crushed to a fine state in the production of building materials. Domain granulated slag (DGS) was used as a research object. A method for introducing fine ground slag (FGS) into the cement composition in the form of a slag suspension instead of mixing water has been developed. To establish the uniform distribution of FGS particles in the cement matrix, the behavior of slag particles in an aqueous dispersion medium was previously studied. The optimal parameters of ultrasonic dispersion of slag suspensions are established: the frequency of ultrasonic vibrations is 44 kHz; temperature of dispersion - 25±2°C; dispersion time - 15 min. It has been established that the application of UST to slag suspensions with the observance of optimal dispersion parameters can increase the aggregative and sedimentation stability of the FGS suspension by 2–3 times as compared with mechanical mixing, accelerate the micelle formation process, and enhance the electrostatic factor of aggregative stability.

Experiments of Green High-Ductile Fiber Low Cementitious Composites

2013 ◽  
Vol 316-317 ◽  
pp. 979-982
Author(s):  
Chang Geun Cho ◽  
Hyun Jin Lim
Keyword(s):  
Mechanical Characteristics ◽  
Cement Composite ◽  
Toxic Substances ◽  
Direct Tension ◽  
Granulated Blast Furnace Slag ◽  
Slump Flow ◽  
Tension Tests ◽  
Flow Compression ◽  
Carbon Dioxide Co2 ◽  
Furnace Slag

The carbon dioxide (CO2) emission during the ordinary Portland cement (OPC) manufacturing process is up to about 7.0 % of global manmade CO2. The OPC is also known to have toxic substances. The purpose of current research is to develop an environmentally green and high-ductile fiber low-cement composite (HDFLC) in which the binder is mixed by replacing the amount of the cement of 60% as the ground granulated blast-furnace slag (GGBS) with or without using alkali activators. The material and mechanical characteristics of the HDFLC were evaluated experimentally by the slump flow, compression, and direct tension tests.

scholarly journals The use of finely ground slag in portland cement with mineral additives

2019 ◽  
Vol 91 ◽  
pp. 02044 ◽  
Author(s):  
Yuri Bazhenov ◽  
Irina Kozlova ◽  
Kirill Nechaev ◽  
Alisa Kryuchkova
Keyword(s):  
Blast Furnace Slag ◽  
Structural Characteristics ◽  
Setting Time ◽  
National Standard ◽  
Cement Stone ◽  
Normal Density ◽  
Granulated Blast Furnace Slag ◽  
Dry Mixing ◽  
Mineral Additives ◽  
Furnace Slag

The method of introducing of finely ground granulated blast furnace slag (GBFS) in the composition of the cement as a result of dry mixing of the material with the additive is considered. The aim of the research was to study the effect of the addition of finely ground slag on the construction, technical, physical, mechanical, and structural characteristics of cement with mineral additives. The setting time was studied, the normal density of the cement paste with the addition of finely ground slag was determined. The dependences of the strength and porosity of the cement stone on the time of hydration of samples are built. The strength of the cement was determined by the national standard GOST 30744-2001. The porosity of the cement stone was determined by saturating the samples with an inert liquid. It has been established that the introduction of 3–5% of slag 1 and 1–3% of slag 2 provides an increase in the strength of cement stone during the first days of hardening on average by 37–44%; at the grade age - by 26–30%, decrease in porosity — by 17–28%. It is shown that the introduction of finely ground slag additives compacts and strengthens the structure of the cement stone. It has been established that grinding GBFS to a size of 1 μm (slag 1) is impractical because the obtained research results are comparable with the results when slag 2 is introduced into the cement composition.

Model and Mechanism of Stabilization of Carbon Nanotubes with Placticizer on the Basis of Sulfonated Naphthalene Formaldehyde Resins

2018 ◽  
Vol 931 ◽  
pp. 481-488
Author(s):  
Svetlana V. Samchenko ◽  
Irina V. Kozlova ◽  
Olga V. Zemskova
Keyword(s):  
Aqueous Suspension ◽  
Double Electric Layer ◽  
High Viscosity ◽  
Polar Component ◽  
Cement Stone ◽  
Ultrasonic Dispersion ◽  
Aqueous Polymer ◽  
Nonpolar Component ◽  
Dispersion Media ◽  
The Stability

The entry presents studies of the effect of dispersion temperature on the deposition rate of CNTs in the presence of a plasticizer based on sulfonated naphthalene formaldehyde resins, on the dispersed composition of CNTs in aqueous and aqueous-polymer dispersion media and on the strength characteristics of samples with stabilized CNTs. It was established that the ultrasonic dispersion of aqueous suspensions of CNTs in the presence of a plasticizer based on sulfonated naphthalene formaldehyde resins at an ultrasonic vibration frequency of 44 kHz; dispersion temperature - 25 ± 2 °C; dispersion time - 10 - 30 minutes is capable of ensuring the stability of CNTs suspensions for 7 days or more. The mechanism of stabilization of aqueous suspension of CNTs by a plasticizer based on sulfonated naphthalene formaldehyde resins is presented. It has been established that the stabilization of CNTs is achieved by fixing the functional groups of the plasticizer on the surface of the nanoparticle, the nonpolar component of which ensures the formation of a high-viscosity interlayer between the CNTs particles and the dispersion medium, and the polar component is the formation of a double electric layer (DEL) that promotes the micellization of CNTs. As a result, the CNTs stabilized with sulfonaphthalene formaldehyde are evenly distributed in the volume of the cement system, causing the production of cement stone with enhanced performance properties.

scholarly journals MODEL AND MECHANISM OF CARBON NANOTUBE STABILIZATION WITH PLASTICIZER BASED ON POLYCARBOXYLATE

Vestnik MGSU ◽  
2017 ◽  
pp. 724-732
Author(s):  
Svetlana Vasilevna Samchenko ◽  
Olga Viktorovna Zemskova ◽  
Irina Vasilevna Kozlova
Keyword(s):  
Portland Cement ◽  
High Viscosity ◽  
Matrix Composition ◽  
Cement Matrix ◽  
Cement Stone ◽  
Modern Theory ◽  
Ultrasonic Dispersion ◽  
Cement System ◽  
Electrical Layer ◽  
The Stability

The method for adding into the cement matrix composition the carbon nanotubes (CNTs) in the form of stabilized suspensions for their even allocation in its volume is observed in this article. The aim of the article is to study the aggregative and sedimentary stability of the CNTs suspensions in the presence of the plasticizer based on polycarboxylate under the ultrasonic effect, to determine the kinetic addictions of coagulation, to describe the suspension stabilization models and mechanisms according to the modern theory and to determine the possibility of using CNTs as suspensions for portland cement modification. The object of research is Portland cement, CNts and polycarboxylate-based plasticizer. Mechanism of stabilization of the CNT water suspension with polycarboxylate based plasticizer due to fixing plasticizer functional groups on the nanoparticle surface is proposed. The non-polar part of the plasticizer provides the formation of high-viscosity streak between the CNTs particles and the dispersion medium, and the polar part provides the formation of the double electrical layer (DEL), which supports the formation of the CNT micelle. The Model of the CNT micelle is described. It is established that the ultrasonic dispersion provides the stability of the CNTs suspensions for seven days and more. It is shown that when the stabilized polycarboxylate-based plasticizers of the CNT are introduced in the form of suspensions into the cement paste composition, they are evenly distributed in the volume of the cement system. This causes the production of cement stone with enhanced exploitative properties.

The Influence of the Properties of the Material Used for Obtaining Geopolymers on Their Structure and Compressive Strength

2017 ◽  
Vol 68 (6) ◽  
pp. 1182-1187
Author(s):  
Ilenuta Severin ◽  
Maria Vlad
Keyword(s):  
Compressive Strength ◽  
Blast Furnace ◽  
Wheat Straw ◽  
Red Mud ◽  
Blast Furnace Slag ◽  
Complex Structure ◽  
Point Of View ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag ◽  
Straw Ash

This article presents the influence of the properties of the materials in the geopolymeric mixture, ground granulated blast furnace slag (GGBFS) + wheat straw ash (WSA) + uncalcined red mud (RMu), and ground granulated blast furnace slag + wheat straw ash + calcined red mud (RMc), over the microstructure and mechanical properties of the synthesised geopolymers. The activation solutions used were a NaOH solution with 8M concentration, and a solution realised from 50%wt NaOH and 50%wt Na2SiO3. The samples were analysed: from the microstructural point of view through SEM microscopy; the chemical composition was determined through EDX analysis; and the compressive strength tests was done for samples tested at 7 and 28 days, respectively. The SEM micrographies of the geopolymers have highlighted a complex structure and an variable compressive strength. Compressive strength varied from 24 MPa in the case of the same recipe obtained from 70% of GGBFS + 25% WSA +5% RMu, alkaline activated with NaOH 8M (7 days testing) to 85 MPa in the case of the recipe but replacing RMu with RMc with calcined red mud, alkaline activated with the 50%wt NaOH and 50%wt Na2SiO3 solution (28 days testing). This variation in the sense of the rise in compressive strength can be attributed to the difference in reactivity of the materials used in the recipes, the curing period, the geopolymers structure, and the presence of a lower or higher rate of pores, as well as the alkalinity and the nature of the activation solutions used.

scholarly journals Effect of Flue Gas Desulfurization Gypsum on the Properties of Calcium Sulfoaluminate Cement Blended with Ground Granulated Blast Furnace Slag

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 382 ◽  
Author(s):  
Danying Gao ◽  
Zhenqing Zhang ◽  
Yang Meng ◽  
Jiyu Tang ◽  
Lin Yang
Keyword(s):  
Blast Furnace ◽  
Mechanical Strength ◽  
Flue Gas ◽  
Blast Furnace Slag ◽  
Setting Time ◽  
Flue Gas Desulfurization ◽  
Calcium Sulfoaluminate Cement ◽  
Calcium Sulfoaluminate ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag

This work aims to investigate the effect of additional flue gas desulfurization gypsum (FGDG) on the properties of calcium sulfoaluminate cement (CSAC) blended with ground granulated blast furnace slag (GGBFS). The hydration rate, setting time, mechanical strength, pore structure and hydration products of the CSAC-GGBFS mixture containing FGDG were investigated systematically. The results show that the addition of FGDG promotes the hydration of the CSAC-GGBFS mixture and improves its mechanical strength; however, the FGDG content should not exceed 6%.

scholarly journals Effect of Mineral Admixtures on the Performance of Low-Quality Recycled Aggregate Concrete

Crystals ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 596
Author(s):  
Yasuhiro Dosho
Keyword(s):  
Blast Furnace ◽  
Fly Ash ◽  
Blast Furnace Slag ◽  
Recycled Aggregate Concrete ◽  
Recycled Aggregate ◽  
Mineral Admixtures ◽  
Structural Concrete ◽  
Aggregate Concrete ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag

To improve the application of low-quality aggregates in structural concrete, this study investigated the effect of multi-purpose mineral admixtures, such as fly ash and ground granulated blast-furnace slag, on the performance of concrete. Accordingly, the primary performance of low-quality recycled aggregate concrete could be improved by varying the replacement ratio of the recycled aggregate and using appropriate mineral admixtures such as fly ash and ground granulated blast-furnace slag. The results show the potential for the use of low-quality aggregate in structural concrete.

scholarly journals Control of the setting reaction and strength development of slag-blended volcanic ash-based phosphate geopolymer with the addition of boric acid

2021 ◽  
Author(s):  
Jean Noël Yankwa Djobo ◽  
Dietmar Stephan
Keyword(s):  
Blast Furnace ◽  
Boric Acid ◽  
Blast Furnace Slag ◽  
Volcanic Ash ◽  
Strength Development ◽  
Main Process ◽  
Reaction Products ◽  
Setting Times ◽  
Granulated Blast Furnace Slag ◽  
Furnace Slag

AbstractThis work aimed to evaluate the role of the addition of blast furnace slag for the formation of reaction products and the strength development of volcanic ash-based phosphate geopolymer. Volcanic ash was replaced by 4 and 6 wt% of ground granulated blast furnace slag to accelerate the reaction kinetics. Then, the influence of boric acid for controlling the setting and kinetics reactions was also evaluated. The results demonstrated that the competition between the dissolution of boric acid and volcanic ash-slag particles is the main process controlling the setting and kinetics reaction. The addition of slag has significantly accelerated the initial and final setting times, whereas the addition of boric acid was beneficial for delaying the setting times. Consequently, it also enhanced the flowability of the paste. The compressive strength increased significantly with the addition of slag, and the optimum replaced rate was 4 wt% which resulted in 28 d strength of 27 MPa. Beyond that percentage, the strength was reduced because of the flash setting of the binder which does not allow a subsequent dissolution of the particles and their precipitation. The binders formed with the addition of slag and/or boric acid are beneficial for the improvement of the water stability of the volcanic ash-based phosphate geopolymer.

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