Low Density Cellular Concrete Made of Reftinskaya SDPP Fly Ash

2017 ◽  
Vol 265 ◽  
pp. 124-128 ◽  
Author(s):  
A.A. Vishnevskiy ◽  
F.L. Kapustin
Keyword(s):  
Fly Ash ◽  
Single Layer ◽  
Drying Shrinkage ◽  
Strength Properties ◽  
Low Density ◽  
Concrete Technology ◽  
Concrete Production ◽  
Aerated Concrete ◽  
Increased Strength ◽  
Cellular Concrete

There is experience of the production and use of low density autoclaved aerated concrete. It is shown that fly-ash from Reftinskaya State District Power Plant efficiently substitutes the quartz sand aerated concrete technology. Its use opens up additional opportunities for AAC with the density of 300-400 kg/m3. In order to optimize the structure and properties it has been suggested to introduce the gypsum aerated concrete additive into the autoclave in the amount of 3-5% by weight of the dry components. The introduction of gypsum ensures the creation of a uniform homogeneous structure, resulting in the increased strength properties and reduced drying shrinkage. The resulting aerated concrete has thermal conductivity of 0.075-0.100 W/m·K, it allows using and creating single-layer fencing structures without additional insulation. The low-density gas-ash concrete production allows extending the scope of cellular concrete application and increasing its competitive advantages over other walls and insulating materials.

The Use of Anthracite Fly Ash for the Production of Autoclaved Aerated Concrete

2012 ◽  
Vol 512-515 ◽  
pp. 3003-3006
Author(s):  
Rostislav Drochytka ◽  
Vit Cerný ◽  
Karel Kulísek
Keyword(s):  
Heat Treatment ◽  
Fly Ash ◽  
Construction Industry ◽  
Raw Materials ◽  
Exothermic Reaction ◽  
Reaction Heat ◽  
Anthracite Coal ◽  
Concrete Production ◽  
Aerated Concrete ◽  
Cellular Concrete

Burning high-quality anthracite coal produces ash with a high content of unburned residues, which in many cases permanently exceeds 20%. These ashes usually contain high levels of amorphous phase providing the pozzolanic activity, this making them particularly useful if potentially applied in the construction industry. Such potential of effective treatment necessitates reducing the content of unburned residues, the best level here being less than 4% w/w. This paper deals with the results of testing heat treatment of fly ashes particularly using the resources of eastern Slovakia. Tests have shown that tested process of heat treatment can safely reduce the content of unburned residues in fly ash whilst maintaining high levels of the glass phase. Raw materials thus modified meet the requirements for the use in cellular concrete production technology with beneficial use of exothermic reaction heat from fly ash treatment in pre-heating the autoclaves.

scholarly journals The sustainable energy approach in the manufacture of cellular concrete

2019 ◽  
Vol 91 ◽  
pp. 02024 ◽  
Author(s):  
Ruben Kazaryan ◽  
Konstantin Belyaev
Keyword(s):  
Environmental Planning ◽  
Single Layer ◽  
Mineralogical Composition ◽  
Treatment Method ◽  
Strength Properties ◽  
Vapor Permeability ◽  
Treatment Changes ◽  
Aerated Concrete ◽  
Moisture Conditions ◽  
Cellular Concrete

Cellular concrete holds one of the leading places in world practice of construction as a structural heat insulating material used in the construction and reconstruction of buildings and structures for various purposes. Excessive (reserve) porosity of cellular concrete provides its frost resistance (compensates expansion of water when freezing and the formed ice without destroying the material). Vapor permeability of cellular concrete provides fast removal of technological moisture from the material and the maintenance of normal moisture conditions in the rooms, and rather high air permeability contributes to the preservation of fresh air in the rooms. Thermal insulation and strength properties of cellular concrete allow erecting single-layer enclosing structures with the required thermal resistance from it. Cellular concretes are divided into aerated concrete and foam concrete, the operating, physical and mechanical parameters of which are almost the same with all other things being equal. According to the hydrothermal treatment method, cellular concrete is divided into two groups: autoclaved and non-autoclaved concrete (air hardening or steaming). The qualities of such concretes differ significantly, since autoclave treatment changes the mineralogical composition of concrete, which greatly affects the profitability of energy-related technological processes associated with the environment and ultimately forms the basis of environmental planning and management.

scholarly journals METHODS OF CELLULAR CONCRETE PRODUCTION USING FLY ASH

2021 ◽  
pp. 114-122
Author(s):  
T.А. Sasovsky ◽  
◽  
I.V. Chorna ◽  
S.V. Shalay ◽  
O.M. Lysiak ◽  
...  
Keyword(s):  
Fly Ash ◽  
Thermal Insulation ◽  
Building Materials ◽  
Practical Interest ◽  
Insulation Material ◽  
Capital Costs ◽  
Concrete Production ◽  
Aerated Concrete ◽  
Capital Construction ◽  
Cellular Concrete

Abstract. An analysis of modern capital construction state shows that the material and technical base of the construction industry does not allow the production of effective building materials and products in the required quantity without due consideration of the economic burden on the environment, and now significant financial costs are required to restore the ecological balance of the natural zone. Power plant fly ash is a man-made raw material for many industries, which is utilized up to 92% in dry form and is of practical interest in the production of effective thermal insulation building materials and products as a filler and an aggregate. In view of the instability of the chemical and mineralogical composition, the content of raw fuel, as well as the pozzolanic activity, the study of the profitability of the production of pozzolanic cements and concretes based on them was carried out, with an increase in sulfate resistance, corrosion resistance of the aggregate while preventing thermal cracking. The expediency of autoclaved gas-ash-slag concretes production with the use of cement with high content of highly basic minerals ‒ alite and tricalcium aluminate is proved. The technology of obtaining ash-alkaline cellular concrete using ash-removal and alkaline component is given. The economic efficiency of cellular ash-containing concretes is justified by the replacement of sand with ash, a 1.2-1.5-fold reduction in lime consumption compared to lime-sand concrete and a reduction of approximately 2 times the capital costs for extraction and processing of raw materials. Comparative physical and mechanical parameters of autoclave and non-autoclave aerated concrete products are given. The process of manufacturing products by vibro-vacuuming and vibratory compaction of ash concrete is presented. The strength data of vacuum concrete are given, which are 30-40% higher than that of vibro- compacted concrete from a rigid mixture. The investigated value of shrinkage as a result of the water-reducing effect of ash, provides a decrease in the water-cement ratio of concrete. Autoclaved and non-autoclaved aerated concrete can compete with such an effective thermal insulation material as mineral wool. They are more effective materials for low-rise and frame housing construction than traditional brick and concrete.

Study on Production of Autoclaved Aerated Concrete by Coal Gangue Fly Ash

2013 ◽  
Vol 357-360 ◽  
pp. 949-954
Author(s):  
Ye Zhang ◽  
Peng Xuan Duan ◽  
Bao Sheng Jia ◽  
Lei Li
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Drying Shrinkage ◽  
Coal Gangue ◽  
National Standards ◽  
Raw Material ◽  
Autoclaved Aerated Concrete ◽  
Binder Ratio ◽  
Material Formulation ◽  
Aerated Concrete

In this paper, the low-silicon coal gangue fly ash is used to produce autoclaved aerated concrete. The influences of water binder ratio, coal gangue fly ash content, calcareous content and conditioning agents on the compressive strength of the autoclaved aerated concrete are investigated. Optimal raw material formulation and procedure are determined for the autoclaved aerated concrete. The compressive strength and frost resistance of autoclaved aerated concrete made by the optimal raw material formulation and procedure meet with the requirements of autoclaved aerated concretes of B05 grade, and its thermal conductivity, drying shrinkage reach the requirements of the relevant national standards of China.

scholarly journals Treatment of Natural Fiber for Application in Concrete Pavement

2021 ◽  
Vol 2021 ◽  
pp. 1-13
Author(s):  
Anteneh Geremew ◽  
Pieter De Winne ◽  
Tamene Adugna Demissie ◽  
Hans De Backer
Keyword(s):  
Natural Fiber ◽  
Low Cost ◽  
Natural Fibers ◽  
Specific Treatment ◽  
Fiber Surface ◽  
Drying Shrinkage ◽  
Concrete Technology ◽  
Treatment Techniques ◽  
Concrete Crack ◽  
Concrete Production

Concrete crack is one of the main problems observed in concrete technology due to drying shrinkage. Incorporating fibers in concrete production is one of the mechanisms implemented to mitigate cracks. Nowadays, investigators concentrate on different techniques to replace human-made fiber with existing natural fibers for fiber-reinforced composite material. Utilization of natural fiber has an initiation for the development of eco-friendly materials by reducing damages caused by human-made materials and saving nonrenewable resources. Natural fibers are readily and abundantly available, sustainable, and biodegradable, with low cost and low density, and have superior specific properties. Nevertheless, there are some limitations of natural fiber compared to human-made fiber. Consequently, significant energy was applied to alter natural fiber’s surface and morphology using physical, chemical, and biological treatment techniques to overcome the limitation. The primary intention of surface treatment is to modify the bond between the fiber surface and the polymer matrix. However, based on this literature review, there were no specific treatment techniques to be followed to select the best one from the others as criteria. It should include all parameters to consider starting from the stage from the cradle to the grave, cost of chemicals, transportation, and labors, including energy consumption and effluent energy. Additionally, their environmental effect also investigated in detail to compare each other.

scholarly journals INVESTIGATION INTO LOW DENSITY POROUS CONCRETE PENETRABILITY BY AIR/MAŽO TANKIO AKYTOJO BETONO ORO LAIDUMO TYRIMAI

1996 ◽  
Vol 2 (7) ◽  
pp. 41-45 ◽  
Author(s):  
Antanas Laukaitis ◽  
Laima J. Kunskaitė
Keyword(s):  
Portland Cement ◽  
Raw Materials ◽  
Low Density ◽  
Product Density ◽  
Porous Concrete ◽  
Acoustical Properties ◽  
Concrete Production ◽  
Cement Binder ◽  
Mixture Samples ◽  
Cellular Concrete

Low-density (250–350 kg/m3) porous concrete has good thermal insulation and acoustical properties. However, the determination of these properties requires a lot of time and is rather costly. Changes in these properties can be determined, if the porous concrete air penetrability, which can be simply found, is known. This paper deals with porous concrete made using Portland cement binder and a binder mixture (lime + Portland cement), as well as with foam concrete air penetrability coefficient value dependency on its density and water/dry solids ratio V/K. The raw materials composition is given in Table 1. Fig. 1 represents the air penetrability determination apparatus scheme. Air penetrability increases with a decrease of density in porous concrete sample. For example, when V/K=0.6 and product density decreases from 490 to 310 kg/m3, the air penetrability coefficient increases from 2.5·10−7to 13.1·10−7 m3/m·S·Pa. Porous concrete air penetrability increases with an increase in V/K (Fig. 2.). The air penetrability coefficient increases from 6·6·10−7 to 12.8·10−7 m3/m·S·Pa when the product density is 350 kg/m3 and V/K changes from 0.5 to 0.7. Changes in V/K have a greater influence on low density porous concrete air penetrability. That is why, when slowly hydrating Portland cement is used for porous concrete production, foaming formation mixture temperature is not high, it binds and is cured very slowly. For higher density product pore structures such a slow curing process does not have any effects, because small, spherical pores prevail. When the water content is increased in the formation mixture, a change in product porous structure is observed, because larger deformed coupled pores are formed and therefore the air penetrability increases. An air penetrability dependency on product density and V/K regression equation (3) is given. Air penetrability coefficients of porous concrete made using a mixed binder (lime + Portland cement) are given in Table 2. It has been established, that a 20% Portland cement equivalent amount of lime in the binder mixture according to equation 1 and when the V/K ratio increased from 0.52 to 0.65, the some density product air penetrability coefficient of equal density products increased by 3 times, while the lime content in the binder increased from 20 to 80% from formation mixture samples with V/K ratio =0.52. Air penetrability of porous concrete made using a mixed binding material also depends on concrete density and formation mixture V/K ratio (Fig. 3.). Cellular concrete air penetrability coefficient values are given in Fig. 4. Cellular concrete differs from porous concrete, because its air penetrability coefficient values decrease with an increase in V/K ratio. This is the reason why cellular concrete air penetrability coefficients are lower than those of porous concrete. Cellular concrete air penetrability coefficient dependency on product density and V/K ratio is expressed by equation 4.

Theoretical Basis of Formation Highly Organized Porous Structure of Aerated Concrete

2019 ◽  
Vol 945 ◽  
pp. 309-317 ◽  
Author(s):  
L.A. Suleymanova ◽  
I.A. Pogorelova ◽  
M.V. Marushko
Keyword(s):  
Porous Structure ◽  
Cellular Structure ◽  
Control Cell ◽  
Air Entrainment ◽  
External Pressure ◽  
Average Density ◽  
Concrete Mixture ◽  
Concrete Technology ◽  
Aerated Concrete ◽  
Cellular Concrete

Theoretical principles of the formation of highly organized porous structure of cellular concrete are developed, based on model concepts of the dynamics of the expanding gas cavity in the liquid phase as a single control cell. The peculiarities of controlling the formation of cellular structure of aerated concrete based on the balance of forces in a three-phase disperse system on the model "gas pore - molding mixture" are revealed and a coalescing-aggregate scheme for porosity formation of the aerated concrete mixture is proposed. It is shown that, in accordance with the refined Rayleigh-Plesset equation, the determining factor in the formation of the cellular structure of aerated concrete is the pressure over the mixture to be poroused, the effect of the porosity being achieved by reducing the external pressure to the vacuum level. The division of pores by size in anaerated concrete mixture is proposed. The maximum pore size is determined by the capillary Laplace constant. The prospects of aerated concrete technology are associated with a decrease in the maximum and average size of cellular pores, as well as methods for eliminating pores of air entrainment and segmented pores. Reducing of the size of the pores will be reflected in the decrease of the Bond quantity and in the increase of the importance of capillary forces in the formation of the porous structure of aerated concrete. The concepts of the types of cellular structures are developed, depending on the average density and their boundaries for cellular concrete are established.

Strength Properties of Autoclaved Cellular Concrete with High Volume Fly Ash

1997 ◽  
Vol 123 (2) ◽  
pp. 44-54 ◽  
Author(s):  
Wenyi Hu ◽  
Ronald D. Neufeld ◽  
Luis E. Vallejo ◽  
Christopher Kelly ◽  
Martin Latona
Keyword(s):  
Fly Ash ◽  
High Volume ◽  
Strength Properties ◽  
High Volume Fly Ash ◽  
Cellular Concrete

Engineering Properties of Concrete with a Ternary Blend of Fly Ash, Wheat Straw Ash, and Maize Cob Ash

2021 ◽  
Vol 54 ◽  
pp. 43-55
Author(s):  
Naraindas Bheel ◽  
Paul O. Awoyera ◽  
Oladimeji B. Olalusi
Keyword(s):  
Fly Ash ◽  
Wheat Straw ◽  
Drying Shrinkage ◽  
Cementitious Materials ◽  
Engineering Properties ◽  
Ternary Blend ◽  
Concrete Production ◽  
Maize Cob ◽  
Agricultural Materials ◽  
Straw Ash

In recent years, recycled materials mostly available in abundant quantities in local agricultural fields are considered as potential constituent material for concrete production. Also, cement production emits many toxic gases in the atmosphere, which causes environmental pollution and greenhouse gases. Thus, recyc;ed materials, such as fly ash (FA), wheat straw ash (WSA), and maize corn ash (MCA) are condered as cementitious binders in concrete for sustainable development. This study aims to determine the engineering properties of concrete with a ternary blend of fly ash, wheat straw ash, and maize cob ash. A total of 73 concrete cubes, 42 reinforced concrete prisms and 42 concrete cylinders were cast to examine mechanical properties of concrete at 7, 28, and 56 curing days. At 28 days (maturity period), the experimental results showed an increase in compressive, tensile, and flexural strength by 12.28%, 9.33%, and 9.93%, respectively, at 9% substitution of ternary cementitious materials (TCM). However, the density of concrete was reduced by 9.92%, with an increase in the TCM content after 28 days. Moreover, the modulus of elasticity was improved by 14.23% with an increase in the content of TCM up to 18% after 28 days, and drying shrinkage of concrete was reduced with the introduction of TCM content after 50 days. However, the workability of fresh concrete decreased as the percentage of TCM increased. Results of this study proved that agricultural materials investgated could be good fit as binder in cementitious composites.

The Use of Fly Ash in the Production of Concrete and Products Based on it

2020 ◽  
Vol 309 ◽  
pp. 8-13
Author(s):  
Fedor Kapustin ◽  
Andrey Vishnevsky
Keyword(s):  
Compressive Strength ◽  
Fly Ash ◽  
Power Plant ◽  
Single Layer ◽  
Early Time ◽  
Fine Aggregate ◽  
Technological Parameters ◽  
Discharge System ◽  
Aerated Concrete ◽  
Reduced Density

Reftinskaya state district power plant owned by Enel company and located in Russia produces up to 5 million tons of fly ash and slag annually when burning multi-ash coal of the Ekibastuz basin. A new system of dry ash removal works at the power plant; it includes the laying system of wet ashes and slags on the dump and the discharge system from the silo storage facility up to 1 million tons of ash per year. The chemical-mineral and grain composition data, properties and their correspondence to Russian standard 25818 in order to use ash in the production of concrete and products based on it are presented. The experience of production and application of autoclaved aerated ash concrete of reduced density is considered. It is shown that fly ash of Reftinskaya state district power plant is an effective substitute for quartz sand in the technology of cellular concrete. Its application opens up additional opportunities for aerated concrete with a density of 300-400 kg/m3 production. To optimize the structure and properties it is proposed to introduce an additive of natural gypsum in the amount of 3-5 % of the mass of dry components into the autoclave aerated concrete. The produced aerated ash concrete had a thermal conductivity of 0.075-0.100 W/m∙K which allows it to be used for erection of single-layer enclosing structures without additional insulation. Fly ash can also be used as part of heavy and fine-aggregate concrete replacing a part of Portland cement and sand. The addition of ash in an amount of up to 25 % by weight of cement improves the workability and reduces the demixing of the concrete mix. Ash introduction up to 10 % increases the compressive strength of concrete at an early time and after 28 days of normal hardening, an increase of it up to 25 % decreases the compressive strength, reduces the conductivity, but increases the shrinkage of concrete. The optimum ash content up to 100 kg/m3 for steamed concrete and not more 50 kg/m3 for normal hardening concrete. Compliance with the optimal composition and technological parameters of the production of concrete structures using ash enables to produce concrete of F200-F300 grade by frost resistance.

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