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 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 The efficiency of plasticizing surfactants in alkali-activated cement mortars and concretes

2018 ◽  
Vol 230 ◽  
pp. 03016 ◽  
Author(s):  
Raisa Runova ◽  
Volodymyr Gots ◽  
Igor Rudenko ◽  
Oleksandr Konstantynovskyi ◽  
Oles’ Lastivka
Keyword(s):  
Compressive Strength ◽  
Blast Furnace Slag ◽  
Chemical Nature ◽  
Granulated Blast Furnace Slag ◽  
Cement Mortars ◽  
Alkaline Component ◽  
Property Modification ◽  
Furnace Slag ◽  
Alkali Activated ◽  
Strength In Bending

Functionality of mortar and concrete mixes is regulated by surfactants, which act as plasticizers. The molecular structure of these admixtures can be changed during hydration of alkali-activated cements (AAC). The objective was to determine the chemical nature of plasticizers effective for property modification of mortars and concretes based on AACs with changing content of granulated blast furnace slag from 0 to 100 %. The admixtures without ester links become more effective than polyesters when content of alkaline component increase. The admixtures effective in high alkaline medium were used in dry mixes for anchoring (consistency of mortar 150 mm by Vicat cone; 1 d tensile strength in bending / compressive strength of mortar 6.6 /30.6 MPa) and in ready-mixed concretes (consistency class changed from S1 to S3, S4 with consistency safety during 60 min; 3 d compressive strength of modified concrete was not less than the reference one without admixtures).

scholarly journals INFLUENCE OF ADDITIVES OF BARIUM-CARBONATE TAILING WASTES ON THE PROPERTIES OF COMPOSITIONAL BINDERS AND CONCRETES

2019 ◽  
Vol 4 (4) ◽  
pp. 24-31
Author(s):  
Н. Сарсенбаев ◽  
N. Sarsenbaev ◽  
А. Аласханов ◽  
A. Alashanov ◽  
А. Айменов ◽  
...  
Keyword(s):  
Barium Carbonate ◽  
Developed Countries ◽  
Industrial Wastes ◽  
Alkali Activated Slag ◽  
Modifying Additives ◽  
Production Wastes ◽  
Analysis And Synthesis ◽  
Alkaline Component ◽  
Activated Slag ◽  
Alkali Activated

The article presents the outcomes of analysis and synthesis of Russian and Kazakh researches on the issue of the use of industrial waste industry for the production of composite slag base binders and concretes. Utilization, liquidation of industrial wastes and their use in the production of composite alkali-activated slag are the issues of global and national importance. Therefore, industrial and developed countries pay great attention to this issue. The influence of the production wastes of the enrichment of polymetallic ores – carbonate-barium tailings on the performance properties (strength, water absorption, density, etc.) of composite alkali-activated slag and concretes is studied. The ways of introducing modifying additives “waste of carbonate-barium tailings” into the composition of alkali-activated slag and concretes are investigated. The optimal amount of introduction the waste of carbonate-barium tailings into the composition of alkali-activated slag of modifying additives is determined. It is 10% of the binder mass and an indicator of effectiveness in influencing the activity of concrete, depending on the type of alkaline component and the hardening conditions. The methods of testing the experimental work to determine the operational properties of alkali-activated slag and concretes based on them are presented.

scholarly journals Alkali-Active Sand Slate Powder for Use as Mineral Admixture in Mass Hydraulic Concrete: Technical and Economic Analysis

2021 ◽  
Vol 2021 ◽  
pp. 1-14
Author(s):  
Xia Chen ◽  
Xian Zhou ◽  
Ziling Peng ◽  
Jiazheng Li
Keyword(s):  
Economic Effects ◽  
Mineral Admixture ◽  
Cement Clinker ◽  
Ternary Blend ◽  
Mass Concrete ◽  
New Approach ◽  
Hydraulic Concrete ◽  
Technical And Economic Analysis ◽  
Autogenous Strain ◽  
Deformation Properties

This work has launched a comprehensive investigation on the macro performance and micro structure of mass concrete produced with alkali-active sand slate powder (ASSP) for use as the mineral admixture and a thorough analysis on its technical and economic effects is also conducted. Results indicated ternary blend with hybrid of 5–8 wt.% silica fume (SF) and 15–20 wt.% ASSP has the optimal compressive and flexural strength. ASSP particle participates in hydration, accelerates hydration of cement clinker within 8.5 hours, and reduces the autogenous strain of pastes by 164 × 10−6 in case of dosage less than 25% by mass. Improvement in the mechanical and deformation properties of concrete produced with the hybrid of SF and ASSP is attributed to better particles gradation, compactness enhancement, and transformation in products of hydration. On the whole, it provides another new approach for use of alkali-active rock after second processing as mineral admixture in hydraulic concrete in terms of good performance and economic effects.

scholarly journals Wastewater Treatment Using Alkali-Activated-Based Sorbents Produced from Blast Furnace Slag

2021 ◽  
Vol 11 (7) ◽  
pp. 2985
Author(s):  
Saverio Latorrata ◽  
Riccardo Balzarotti ◽  
Maria Isabella Adami ◽  
Bianca Marino ◽  
Silvia Mostoni ◽  
...  
Keyword(s):  
Low Cost ◽  
Steel Production ◽  
Metallurgical Industry ◽  
High Alumina ◽  
Ambient Conditions ◽  
Good Opportunity ◽  
Metal Capture ◽  
Mine Effluent ◽  
Alkaline Component ◽  
Alkali Activated

Currently, slags from secondary steel production, foundries, and blast furnaces represent a major environmental problem since they end up mainly in landfills, and their valorization would bring undeniable advantages both to environment and economy. Moreover, the removal of heavy metal ions from mines wastewater is one of the challenges of the last decades, and adsorption has been proposed as one of the most promising techniques for this purpose. In this context, the use of alkali-activated slags as sorbent can be a good opportunity to develop low cost, environmentally friendly, and sustainable materials. Accordingly, wastewater decontamination by adsorption over a porous monolithic bed made of alkali-activated hydraulic binders is proposed. Alkali-activated materials were prepared using slags from the metallurgical industry and reacted with an alkaline component (high alumina calcium aluminate cement, CAC 80) at ambient conditions. The obtained monolithic foams were tested to evaluate the uptake efficiency towards metal capture. Solutions containing Cu(II), Fe(III), Ni(II), Mn(II), and simulating the metal concentrations of a real mine effluent were tested, both in single- and multi-ion solutions. Promising capture efficiency, values of 80–100% and of 98–100% in the case of the single ion and of the multi-ion solutions were obtained, respectively.

scholarly journals Alkali Activation of Copper and Nickel Slag Composite Cementitious Materials

Materials ◽  
2020 ◽  
Vol 13 (5) ◽  
pp. 1155 ◽  
Author(s):  
Tingting Zhang ◽  
Shiwei Zhi ◽  
Tong Li ◽  
Ziyu Zhou ◽  
Min Li ◽  
...  
Keyword(s):  
Glass Phase ◽  
Chemical Activation ◽  
Cementitious Materials ◽  
Mineral Admixture ◽  
Alkali Activation ◽  
Hydration Products ◽  
Granulated Blast Furnace Slag ◽  
Ft Ir ◽  
Furnace Slag ◽  
Alkali Activated

Alkali-activated copper and nickel slag cementitious materials (ACNCMs) are composite cementitious materials with CNS (copper and nickel slag) as the main materials and GGBFS (ground-granulated blast-furnace slag) as a mineral admixture. In this paper, the activity indexes of CNS with different grinding times were studied using CNS to replace a portion of cement. NaOH, Na2SO4, and Na2SiO3 activators were used to study the alkaline solution of the CNS glass phase. The effects of the fineness of CNS and the type of activator on the hydration of ACNCMs were investigated via physical/mechanical grinding and chemical activation. The hydration products of ACNCMs were analyzed via XRD, SEM, FT-IR, TG, and MIP. The results of the study revealed that the activity indexes of CNS ground with different grinding times (10, 30 and 50 min) were 0.662, 0.689, and 0.703, respectively. When Na2SiO3 was used as the activator, the glass phase dissolved the most Si4+, Al3+, and Ca2+, and the respective concentrations in the solution were found to be 2419, 39.55, and 3.38 mg/L. Additionally, the hydration products of ACNCMs were found to have a 28-day compressive strength of up to 84 MPa.

Long-Term Deformation Properties of a Carbon-Fiber-Reinforced Alkali-Activated Cement Composite

2020 ◽  
Vol 56 (1) ◽  
pp. 85-92 ◽  
Author(s):  
R. Gailitis ◽  
J. Sliseris ◽  
K. Korniejenko ◽  
J. Mikuła ◽  
M. Łach ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Cement Composite ◽  
Fiber Reinforced ◽  
Deformation Properties ◽  
Carbon Fiber Reinforced ◽  
Alkali Activated ◽  
Alkali Activated Cement

Research on Activation of Abandoned Mortar Power Construction Waste

2010 ◽  
Vol 168-170 ◽  
pp. 1222-1227
Author(s):  
Bao Guo Ma ◽  
Lei Su ◽  
Shou Wei Jian ◽  
Xue Feng Song ◽  
Yu Dong Zhai
Keyword(s):  
Mechanical Properties ◽  
Compressive Strength ◽  
Flexural Strength ◽  
Mineral Admixture ◽  
Hydration Products ◽  
Mechanical Grinding ◽  
Compact Structure ◽  
Construction Waste ◽  
Power Construction ◽  
Alkali Activated

Through crushing, screening and grinding, abandoned mortar power can be used as a mineral admixture to replace cement. Physical-activated, alkali-activated and composite-activated have been researched on activity of abandoned mortar power. Mechanical properties and microstructure were tested by compressive strength, flexural strength, XRD, TG-DSC-DTC and SEM. The results show that: Mechanical grinding and activator can significantly improve the activity of mortar power. Stimulating effect of single activator was not obvious. Composite activator has better effect than signal activator and it can promote further hydration of cement. The mortar which is stimulated by composited activator had higher strength than mortar with single activator. It can be seen from micro-test, the mortar with composite activator had more ettringite and other hydration products, having compact structure.

scholarly journals Study of influence of alkaline component type on pH value and properties of alkali activated concretes containing basalt rock

2021 ◽  
Vol 280 ◽  
pp. 07001
Author(s):  
Oleksandr Kovalchuk ◽  
Victoriya Zozulynets
Keyword(s):  
Ph Value ◽  
Normal Structure ◽  
Formation Processes ◽  
Strength Gain ◽  
Concrete Mix Design ◽  
Component Type ◽  
Alkaline Component ◽  
Alkali Activated ◽  
Basalt Rock ◽  
Alkali Activated Cement

The paper discusses the questions of alkalinity changes in alkali activated cement-based materials at different stages of hardening. It was shown that use of alkali activated cement with dry alkaline component (“all-in-one system”) in the presence of basalt rock leads to the immediate decrease of pH value and strength drop of the material. On the other hand, using alkaline component in the form of alkaline solution provides almost normal hardening of systems. Taking into account obtained results a methodology of changes in concrete mix design was proposed. In general, for different cement systems under study pH value varies from 8.5 to 12 reflecting on the materials structure formation processes and strength gain. Shrinkage of the systems was within the ranges 0.3…0.6 mm/m at 28 days age and 0.3…0.5 mm/m for different systems. Absence of expansion witnesses about compensation of ASR results and normal structure developments processes in the material comparing to OPC.

Sign in / Sign up

Export Citation Format

Share Document