scholarly journals The Effect of the Composition of a Concrete Mixture on Its Volume Changes

Materials ◽  
2021 ◽  
Vol 14 (4) ◽  
pp. 828
Author(s):  
Martin Ťažký ◽  
Lenka Bodnárová ◽  
Lucia Ťažká ◽  
Rudolf Hela ◽  
Milan Meruňka ◽  
...  
Keyword(s):  
High Temperature ◽  
Fly Ash ◽  
Specific Effect ◽  
Mineralogical Composition ◽  
Point Of View ◽  
Volume Changes ◽  
Granulated Blast Furnace Slag ◽  
Concrete Mixtures ◽  
The Individual ◽  
Mineral Additives

The presented research aims to clarify the specific effect of the individual components of concrete with Portland cement CEM I 42.5 R on the volume changes of concrete. The effect of the filler component was evaluated from the point of view of the composition and type of aggregate (crushed versus mined) and from the point of view of the mineralogical composition of the aggregate. Concrete formulas with a maximum aggregate grain size of 16 and 22 mm were assessed. The effect of the binder component on the shrinkage of the concrete was monitored on the concrete mixtures produced using the same aggregate and maintaining the same strength class of concrete, C 45/55. The effect of the addition of finely ground limestone, finely ground granulated blast furnace slag and coal high-temperature fly ash was monitored. It was found that the maximum aggregate grain and the type of grading curve do not have a significant effect on the volume changes of concrete. Concretes with mined aggregates showed lower shrinkage than concretes with crushed aggregates. The most significant is the effect of the type of aggregate on the volume changes in the first 24 h. Mineral additives have a positive effect on the elimination of the volume changes of concrete, while the addition of high-temperature fly ash proved to be the most suitable.

scholarly journals Fine ground granulated blast furnace slag for saving quantity of binder

2019 ◽  
Vol 110 ◽  
pp. 01055
Author(s):  
Liliya Kazanskaya ◽  
Nicolay Privalov ◽  
Svetlana Privalova
Keyword(s):  
Blast Furnace ◽  
Portland Cement ◽  
Blast Furnace Slag ◽  
Mineralogical Composition ◽  
High Specific Surface Area ◽  
Resource Saving ◽  
Water Reduction ◽  
Granulated Blast Furnace Slag ◽  
Mineral Additives ◽  
Furnace Slag

Nowadays, it is acknowledged that the use of mineral additives based on ground slag is one of ways of resource saving and improvement of technical properties of cement composites. Mineral additives with fineness similar to the Portland cement fineness are often used to replace part of Portland cement. Two kinds of ultra-fine ground granulated blast furnace slag that differ in composition and fineness were studied in the paper. Water-reduction due to effect of super plasticizer in slag-Portland cement compositions with amount of slag up to 70% was studied. The results of reduction of binder quantity per 1 kg of chemical admixture due to significant water-reduction are obtained and analysed. Correlations depending on kind, amount and fineness of slags, as well as depending on mineralogical composition of Portland cement were stated. The ultra-fine mineral additives based on ground slag with high specific surface area can be used for significant reduction of compositional binder.

Reviews on the Geopolymer Materials for Coating Application

2012 ◽  
Vol 626 ◽  
pp. 958-962 ◽  
Author(s):  
Yahya Zarina ◽  
Mohd Mustafa Al Bakri Abdullah ◽  
H. Kamarudin ◽  
I. Khairul Nizar ◽  
Rafiza Abd Razak
Keyword(s):  
Blast Furnace ◽  
High Temperature ◽  
Fly Ash ◽  
Blast Furnace Slag ◽  
Coating Application ◽  
Existing Structures ◽  
Granulated Blast Furnace Slag ◽  
Temperature Exposure ◽  
New Applications ◽  
Furnace Slag

The application of geopolymer has been expand in many areas where before this it only used for the production of cement and concrete. One of the new applications of geopolymer is for coating. Metakaolin, fly ash and granulated blast furnace slag has been used as source for the production of geopolymer coating. The result for the geopolymer coating showed that it can prevent corrosion in seawater structure, high bonding strength between existing structures (OPC concrete), lower water permeability and also stable during high temperature exposure.

scholarly journals Abrasive Wear Resistance of Concrete in Connection with the Use of Crushed and Mined Aggregate, Active and Non-Active Mineral Additives, and the Use of Fibers in Concrete

2020 ◽  
Vol 12 (23) ◽  
pp. 9920
Author(s):  
Lenka Bodnárová ◽  
Martin Ťažký ◽  
Lucia Ťažká ◽  
Rudolf Hela ◽  
Ondřej Pikna ◽  
...  
Keyword(s):  
Abrasion Resistance ◽  
Age Groups ◽  
High Strength ◽  
Mineralogical Composition ◽  
Concrete Mixtures ◽  
Standard Procedures ◽  
Different Types ◽  
The Impact ◽  
Mineral Additives ◽  
Active Mineral Additives

Virtually every concrete structure comes into contact with abrasive effects of flowing media or solids, which have a direct impact on the durability of concrete. An abrasive effect is most pronounced in transport or water management structures, and these structures are often designed for a significantly longer service life (usually 100 years). This research evaluates the influence of the filler component in terms of the type of aggregate and its mineralogical composition on concrete abrasion resistance. As part of the impact of the binder component, several concrete mixtures were produced using the same aggregate and maintaining the same strength class with the addition of different types of active and inert mineral additives. In other parts of the research, the effect of adding fiber reinforcement on the abrasion resistance of concrete was verified. Mutual connections and correlations in different age groups (7, 28 and 90 days) were sought for all obtained results. The abrasion resistance of the composite was monitored by using standard procedures, especially using a Böhm device. It was found that for good abrasion resistance of concrete, it is not necessary to produce concretes with high strength classes using often expensive mineral additives (microsilica) and quality aggregates, but the maturation time of the composite and its microstructure plays an important role.

scholarly journals STUDY OF SORPTIVITY OF SELF‐COMPACTING CONCRETE WITH MINERAL ADDITIVES

2006 ◽  
Vol 12 (3) ◽  
pp. 215-220 ◽  
Author(s):  
Luiz Antonio Pereira de Oliveira ◽  
João Paulo de Castro Gomes ◽  
Cristiana Nadir Gonilho Pereira
Keyword(s):  
Fly Ash ◽  
The Self ◽  
Capillary Absorption ◽  
Self Compacting Concrete ◽  
Normal Concrete ◽  
Hydraulic Lime ◽  
Concrete Mixtures ◽  
Slump Flow ◽  
Different Types ◽  
Mineral Additives

This work presents the results of a comparative study of the sorptivity, accomplished in mixtures of selfcompacting concrete with different types of additives and a normal concrete compacted by vibration. The self‐compacting concrete mixtures present slump‐flow of 650 ± 50 mm and have the same cement contents. In the self‐compacting mixtures, were used as additives, fly ash, silica fume, hydraulic lime and a mixture of fly ash and hydraulic lime. A modified carboxylates superplasticiser was used to obtain a specific workability. The capillary absorption was carried out at 7, 14 and 28 days of age, through a methodology described in the work. The results permit to conclude that the used additives propitiate the self‐compacting concrete. In terms of capillary absorption, the mixtures with fly ash have a better performance.

The Influence of Shrinkage-Reducing Additives on Volume Changes and Mechanical Parameters of a Concrete Composite

2021 ◽  
Vol 325 ◽  
pp. 125-130
Author(s):  
Milan Meruňka ◽  
Lucia Ťažká ◽  
Rudolf Hela
Keyword(s):  
High Temperature ◽  
Fly Ash ◽  
High Performance ◽  
Cement Hydration ◽  
Heat Of Hydration ◽  
The Other ◽  
Cement Stone ◽  
Mechanical Parameters ◽  
Volume Changes ◽  
Significant Development

Cement hydration is a process during which the setting and hardening of cement stone occur. This process is linked to the significant development of heat of hydration, which is accompanied by volume changes of concrete composite (i.e. shrinkage). Due to this, cracks in a concrete composite can arise and influence not only its durability, mechanical parameters or aesthetics but, in the case of water-tight concretes (e.g. the so-called white boxes), also its function. The extent of volume changes can be influenced not only by the composite structure itself or the selection and amount of cement but also by using suitable active additions, e.g. high-temperature fly ash. As a result, it is possible to reduce the amount of cement required while maintaining identical mechanical parameters of concrete and, at the same time, slow down the progress of heat of hydration during cement hydration. One of the other options to eliminate volume changes in concrete composites is the use of shrinkage-reducing additives (SRA). This article focuses on the SRA influence on volume changes of high-performance concretes and their impact on the development of hydration temperatures and mechanical parameters of composites.

Structural Behaviour of Ferrogeopolymer Slabs under Flexure

2016 ◽  
Vol 866 ◽  
pp. 109-113
Author(s):  
Rathinam Kumutha ◽  
Kanagarajan Vijai ◽  
P. Rajeswaran
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Mild Steel ◽  
Double Layers ◽  
Fine Aggregate ◽  
Test Results ◽  
Structural Behaviour ◽  
Granulated Blast Furnace Slag ◽  
Binder Ratio ◽  
The Individual

The main objective of this paper was to present the results of experimental investigation carried out to study the structural behaviour of ferrogeopolymer elements under flexure. Initially the properties of geopolymeric binder prepared using the source materials such as Fly ash and Ground Granulated Blast Furnace Slag (GGBS) without conventional cement have been investigated. The different parameters considered in this study are the ratio of binder to fine aggregate (1:2 and1:3) and the ratio of Na2SiO3 to NaOH solutions (2.0 and 2.5). The various combinations of Fly ash and GGBS considered are 90% & 10% and 80% & 20%. The alkaline liquid to binder ratio is fixed as 0.45. The individual properties of mortar such as Compressive Strength and Density were determined as per relevant Indian standards. The geopolymer concrete mix that gives the highest compressive strength was used to cast the ferrogeopolymer structural slabs. Four numbers of rectangular slabs of size 800 mm x 300 mm x 25 mm were prepared with two types of meshes such as mild steel and galvanized iron weld mesh with single and double layers. Based on the test results Load-Deflection curves were drawn and the effectiveness of mild steel and galvanized iron weld meshes was compared from the characteristics such as first crack load, ultimate load, energy absorption and ductility.

scholarly journals Analysis of Changes in the Microstructure of Geopolymer Mortar after Exposure to High Temperatures

Materials ◽  
2020 ◽  
Vol 13 (19) ◽  
pp. 4263
Author(s):  
Marta Dudek ◽  
Mateusz Sitarz
Keyword(s):  
High Temperature ◽  
Fly Ash ◽  
High Temperatures ◽  
Test Results ◽  
Spectroscopy Analysis ◽  
Granulated Blast Furnace Slag ◽  
Current State ◽  
High Durability ◽  
Digital Microscope ◽  
Microstructure Of The Material

The inorganic structure formed at the stage of setting of the geopolymer binder ensures high durability of the material under high-temperature conditions. However, changes in the microstructure of the material are observed. The purpose of the study was to analyze changes in the structure of geopolymer mortar after exposure to high temperatures T = 200, 400, 600, 800, and 1000 °C. Mortars with a binder based solely on fly ash (FA) and mixed in the 1:1 ratio with a binder containing fly ash and ground granulated blast-furnace slag (GGBFS) were tested. The descriptions of their microstructures were prepared based on digital microscope observations, scanning electron microscope (SEM) observations, EDS (energy dispersive spectroscopy) analysis, and mercury intrusion porosimetry (MIP) porosity test results. Changes in the material due to high temperature were observed. The differences in the microstructure of the samples are also visible in the materials that were not exposed to temperature, which was influenced by the composition of the materials. Porosity increases with increasing annealing temperature. The distribution of individual pores also changes. In both materials, the proportion of pores larger than 1000 nm increases with the temperature increase. Moreover, the number of cracks and their width also increases, reaching 20 µm in the case of GGBFS. Furthermore, the color of geopolymers has changed. The obtained results extend the current state of knowledge in the field of changes in the microstructure of geopolymers subjected to high temperature.

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