Chemical Composition Of Fly Ash Research Articles

Geotechnical Properties of Fly Ash Blended Expansive Soil: A Review

Fly ash, an industrial byproduct, is used as both a building material and a soil stabilizer due to its pozzolanic properties. Moreover, it is challenging to extrapolate the results based on an inadequate amount of laboratory data because of the non-homogeneous character of the soil and the diversity in the chemical properties of fly ash. This review article fills in the gaps by providing an overview of the existing data related to the geotechnical characteristics of expansive soil stabilized with fly ash. The chemical composition of fly ash is provided in terms of oxides of various elements to help identify the kinds produced in different nations. Additionally, information about the physical and geotechnical characteristics of fly ash blended expansive soil is provided in order to comprehend the influence of the fly ash's chemical composition and the expansive soil's fines percentage. While the geotechnical property comprises Atterberg's limit, compaction, UCS, shear strength, free swelling index, CBR, and consolidation, the physical property includes specific gravity and durability. Shear modulus, damping ratio, and Poisson's ratio are used to describe the dynamic properties of the modified expansive soil. The published data in this field and the research gap will be identified by the researchers with the aid of this article. Doi: 10.28991/CEJ-SP2024-010-06 Full Text: PDF

Potential of fly ash geopolymer concrete as repairing and retrofitting solutions for marine infrastructure: A review

Corrosion in maritime infrastructure, particularly in reinforced concrete, has emerged as a significant cause for concern due to the presence of chloride ions in seawater. To address this challenge, geopolymer concrete has been proposed as a viable solution for retrofitting and restoring marine structures. This review paper explores the potential application of fly ash geopolymer concrete in marine infrastructure restoration. Fly ash's properties make it ideal for marine infrastructure restoration. Its high levels of amorphous silica and alumina enable geopolymerization, forming a strong binder resistant to chloride corrosion. Its fine, spherical particles enhance concrete workability and density, improving mechanical strength and impermeability. This geopolymer binder offers excellent resistance to corrosion from chloride ions commonly found in seawater, making fly ash geopolymer concrete highly suitable for marine applications. Overall, fly ash's chemical composition and physical traits offer resilience and sustainability in restoring marine infrastructure, ensuring long-term durability against corrosion. This review paper explores the potential application of fly ash geopolymer concrete in marine infrastructure restoration. By examining the primary forms of damage and mechanisms underlying concrete degradation in marine settings, this study highlights the durability and sustainability of geopolymer concrete compared to traditional concrete. Additionally, it discusses current solutions for repairing and retrofitting concrete in marine environments, emphasizing the promising characteristics of geopolymer concrete for integration into such structures. Through this analysis, innovative and environmentally conscious approaches are introduced for addressing corrosion-related challenges in the maritime industry, offering a resilient solution for the construction of enduring marine structures. Finally, recommendations for further research on the application of fly ash geopolymer concrete in marine infrastructure restoration are presented.

Management of Fly Ash to Synthesise Geopolymers and Zeolites

The purpose of the article was to conduct an in-depth literature review on the possibilities of managing combustion by-products (mainly fly ash) in the context of a closed-loop economy. First, information on the chemical composition of fly ash in Poland was collected and compared with the composition of fly ash in other European countries. The authors concentrated on describing methods for synthesizing geopolymers and zeolites using fly ash as a substrate. By-products of zeolite synthesis, which are strongly alkaline solutions, can be used as a substrate in the synthesis of geopolymers. A concept has been proposed to combine the synthesis of zeolites and geopolymers into a single process to close the material loop. The search for comprehensive technological solutions that take into account the ideas of a closed-loop economy is essential in an era of resource depletion, and this literature review encapsulates this topic area.

Технология утилизации и использования золошлаковых отходов для обеспечения экологической безопасности региона

Introduction. By burning coal, thermal power plants receive thermal energy and generate electrical energy. The negative side of this process is the formation of ash and slag waste. The relevance and significance of this problem is due to the fact that technogenic waste from the CHP is not processed, and current ash waste accumulates and occupies huge areas, which removes them from land use. This problem is especially relevant for Almaty, where ash and slag waste from the burning of coal from the Ekibastuz deposit in Kazakhstan is concentrated. Currently, in Kazakhstan, ash and slag waste from thermal power plants is accumulated in the amount of more than 500 million rubles, the reserves of which continue every year. The storage of ash and slag waste leads not only to the seizure of significant land areas, but also causes very significant pollution of almost all environmental components in the area of their location. Therefore, at mining enterprises that have their own thermal power plants, it is very urgent to solve the issues of reducing the burden on the environment by developing technologies for the disposal of ash and slag using them in the production of road surfaces. The purpose of the research. The study of the physico-chemical properties of ash and slag waste to reduce the anthropogenic load on the environment. Research materials. For the research, samples of Ekibastuz coal ash taken from the ash dumps of the CHPP-3 in Almaty were used. Research methods. The work was carried out using a DRON-3M diffractometer to determine the phase composition of ash and slag waste. The chemical composition of fly ash was determined by the X-ray fluorescence spectrometer EDX-8000. The granulometric composition was analyzed using an Analizette 22 MicroTec Fritsch GmbH (Germany). Microphotography of fly ash was taken using a Superprobe-733 scanning electron microscope with software. To determine the physical and mechanical properties of the bases using bitumen-ash-slag binder, the crushed stonegravel-sand mixture is initially mixed with ash-slag. From the finished bitumen – mineral mixture, samples are prepared by pressing – cylinders with a size of 5x5 cm. The ultimate strength was determined for two types of samples. The first are dry, tested immediately after receiving samples by pressing, the second are samples that are tested after water saturation. Research results and discussion. Based on the study of the physic-mechanical properties of the binder with the use of ash and slag, a technology for obtaining BZSHV has been developed. Various compositions are proposed – types of bitumen, depending on the type of base of asphalt concrete mixtures. Studies have shown that the introduction of ash and ash-slag mixtures from the burning of stone and brown coals as a mineral powder for the preparation of asphalt concrete mixtures makes it possible to obtain a material with regulatory physic-chemical characteristics. Conclusion. The results of the study of the main physic-chemical characteristics of the ash of Ekibastuz coal, selected from the ash dumps of the CHP-3 of Almaty city, are presented. It is shown that the use of ash in the manufacture of asphalt pavement will reduce the area of occupied land and the load on the environment, as well as improve the operational characteristics of the pavement. Suggestions for practical application. The results of the research can be useful in solving the environmental problem of utilization of ash and slag waste of the CHP.

Carbon Emissions Assessment Fly ash and Steel Slag As a Substitute for Cement in Concrete Mixing Using the Method Artificial Neural Networks

Concrete is a construction material made from a mixture of Portland cement, air, coarse aggregate, fine aggregate, and sometimes also uses admixture materials with a certain ratio. Cement, which is the binding agent in the concrete mixture, contributes to 8% of the world's carbon dioxide (CO2) emissions. Fly ash and steel slag are one of the wastes that are currently being researched and developed as cement ingredients in concrete mixtures. This is because the chemical composition of fly ash and slag associated with cement is very suitable when added to concrete mixtures.This study aims to find out of the optimal of fly ash and slag content in the concrete mixture in terms of strength by using the Artificial Neural Network (ANN) method and in accordance with SNI 7656: 2012. Furthermore, this study also aims to measure the ratio of CO2 emissions that are produced from normal concrete, concrete with fly ash, and concrete with steel slag, using references from Idemat2014 and Ecoinvent V3.The results showed that the optimum content of fly ash class F, fly ash class C, and steel slag in the concrete mixture were 30%, 20%, and 55%, respectively. The results also concluded that steel concrete slag as the lowest emitter of CO2 compared to normal concrete, class F fly ash concrete, and class C fly ash concrete. Keywords: concrete, fly ash, steel slag, ANN, comppresive strength, CO2 emission

The comparative study of using wood ash in lieu of fly ash in South African blended cement paste and mortar

A comparative analysis of the properties of fly ash (FA) and wood ash (WA) blended cement, produced in the controlled environment of a cement factory was examined. Since FA has been adopted in South Africa as a material for blended cement, the possibility of using wood ash in lieu of FA to produce blended cement was investigated. The blended cements were prepared and tested at AfriSam (South Africa) Ltd. Roodepoort, with 10 % and 25 % FA and WA as partial substitution for Ordinary Portland Cement (OPC) clinker (CEM1). The chemical composition of FA and WA, the setting times of the blended cement pastes and the compressive strengths of the blended cement mortars were analyzed and discussed. The results indicated that FA and WA have combined SiO2, Al2O3 and Fe2O3 constituents of 89.29% and 72. 58%, respectively. Also, lower initial and final setting times were observed with 25% WA samples as compared to the control sample and FA samples. WA blended cement showed faster rate of hydration than FA blended cement at early curing age resulting in mortar compressive strength of 26.2 MPa and 25.4 MPa as well as 22.6 MPa and 19.2 MPa for 10% and 25% WA and FA substitution respectively. However, FA blended cement mortar exhibited higher late strength than WA blended cement mortar with 10% FA blended cement mortar resulted in higher compressive strength than control sample at 90 days. The combined synergy of WA and FA in blended cement is envisaged to produce mortar of desirable early and late strengths.

Characteristics and Chemical Composition of Fly Ash From Pulang Pisau’s Power Plant as A Potential Material for Synthesis of Aluminosilicate Materials

The Steam-Electric Power Station (PLTU) is one of the initiatives to meet the nation's current electricity requirements. The use of fuel for steam power plant is still dominated by fossil fuels such as coal. Even though domestic energy needs are met, steam power plant turns out to be a contributor to gas emissions that cause global warming, as well as a by-product in the form of fly ash which can cause environmental and ecosystem problems. Fly ash contains silica oxide (SiO 2 ) and aluminum oxide (Al 2 O 3 ) compounds which can be used as raw materials for synthesizing aluminosilicate-based materials such as geopolymers and zeolites. This study tested the characteristics and composition of chemical compounds in fly ash from Pulang Pisau’s power plant, Central Kalimantan. Characterization using X-Ray Diffraction (XRD) showed that peaks of quartz material dominated fly ash from Pulang Pisau’s power plant at 2θ=20.82°;26.61° and mullite minerals at 2θ= 31.2°;33.1°; 35.4°;39.2°;59.8°. The results of the chemical compound composition were tested using the ASTM-D3682-12 standard. Fly ash has a composition of 29.00% SiO 2 , 9.98% Al 2 O 3 , 13.75% Fe 2 O 3 , and 28.37% CaO. Fly ash from Pulang Pisau’s power plant is classified as type C fly ash, which can potentially be used as a source of aluminosilicate-based material synthesis.

The physical and chemical composition of fly ash from Troitsk state district power plant (GRES) and its potential use in the construction industry

This paper deals with the use in construction of fly ash, bottom ash, and slag waste from thermal power plants. Using material from the Troitsk State District Power Plant (GRES), we studied the potential use of slag and ash, as well as thermal power by-products, which occupy large areas, pollute the environment, and negatively affect human health. If we correctly approach this problem, fly ash and slag can be used in concrete, replacing part of the cement content, or as an aggregate, which will increase the resistance of concretes to environmental impacts, and therefore become an effective raw material for the production of building materials. Studies have shown ash is most effectively used as an additive in cement and in the production of fine-grained concretes. Ash from thermal power plants are mostly used in the form of porous ash aggregates, including unburned fly-ash aggregate. This study contributes to the effective use of ashes from Troitsk GRES in the production of light concretes. The use of these ashes in the production of heat-insulating wall materials will allow an increase in the efficiency of residential and industrial construction. This can lead to the development of the construction industry in the region and job gain while reducing the environmental impact.

A Review on Properties and Applications of Fly Ash

This article is an overview on the key properties and applications of fly ash. Fly ash, a byproduct of coal combustion, possesses diverse properties that make it a valuable resource with various applications. The chemical composition of fly ash includes oxides and trace elements, influencing its suitability for different applications. Physical characteristics such as particle size distribution and density play crucial roles in determining its behavior in various environments. Fly ash is widely utilized in concrete production, enhancing both strength and durability. Its applications extend to agriculture, where it improves soil quality and enhances crop yields. Innovative applications, including nanomaterial synthesis and alternative construction materials, showcase the potential for future research and development in the field of fly ash utilization. This article highlights the multifaceted nature of fly ash, emphasizing its significance in both current applications and future trends.

Geotechnical Behaviour of Fly Ash–Bentonite Used in Layers

Increasing infrastructure growth has forced the construction industry to look for wasteful, cheap, and suitable materials for construction. An investigation into the geotechnical utilization of fly ash was carried out in the present study. Practical applications normally involve the use of large quantities of fly ash, so proper mixing of the fly ash with other materials may not be significantly achieved. Therefore, the present paper investigates the behaviour of a fly ash–bentonite layered system with different ratios. The physical properties and chemical composition of fly ash and bentonite were determined. SEM and energy dispersive X-ray experiments were also used to investigate the morphology and phase compositions of fly ash and bentonite. A series of consolidated undrained (CU) triaxial tests on fly ash–bentonite were carried out to investigate shear strength characteristics. Fly ash (F) and bentonite (B) were used in the following ratios: 1:1 (50% F:50% B), 2:1 (67% F:33% B), 3:1 (75% F:25% B), and 4:1 (80% F:20% B), with different numbers of interfaces (N), i.e., 1, 2, and 3 for each ratio. The deviator stress and cohesion value were found to increase with the number of interfaces for each ratio. The angle of shear resistance changed marginally with the increase in the fly ash–bentonite ratios and varying interfaces.

Coal combustion emissions and ash formation characteristics during oxy-fuel combustion in a 100 kWth pressurized circulating fluidized bed

Pressurised circulating fluidized bed oxy-fuel combustion (PCFB-OFC) is a promising technology for CO2 capture because of its high carbon capture efficiency and net efficiency. However, there is a lack of comprehensive experimental studies on PCFB thermal state experimental devices due to the complexity of their design, construction, and operation. In this study, a 100 kWth PCFB-OFC experimental device was developed, and a series of coal combustion experiments were conducted under 0.1 to 0.6 MPa at an average oxygen concentration of 30% with a fixed peroxygen coefficient β (1.1–1.3). The effect of combustion pressure was investigated to determine the influence of pressure on coal combustion efficiency, furnace temperature distribution, gaseous pollutant emissions, and fly ash chemical composition. The experimental results showed that the increase in pressure increased the particle concentration in the dilute phase zone and increased the temperature at the top of the furnace, with a more uniform temperature distribution. The carbon content in the fly ash and the CO emissions in the flue gas were gradually reduced, and the combustion efficiency increased to 97.3%. The emissions of NO and N2O gradually decreased with the increase in load, and the NO emissions reduced by approximately 70% at 0.6 MPa. The emission of SO2 showed a downward trend as the pressure increases. Affected by the increase in pressure, the self-desulfurization capability of fly ash was improved. In addition, lower K2O and Na2O contents may reduce the deposition of fly ash in the furnace.

Technological and Environmental Behavior of Coal Fly Ash in Lime-Based Materials

Coal fly ash is considered an industrial by-product derived from coal combustion in thermal power plant. It is one of the most complex anthropogenic materials. Its improper disposal has become an environmental concern and resulted in a waste of recoverable resources. The aim of this paper is to study the physico-chemical characteristics of binders based on coal fly ash and lime in order to develop an eco-cement. The various characterization tests carried out are X-ray fluorescence, X-ray diffraction, compressive strengths, thermophysical properties and setting time. X-ray fluorescence and X-ray diffraction were used to determine the chemical composition and phases of fly ash, lime and binders. This allowed us to see that the chemical composition of fly ash is similar to that of cement. Compressive strengths of mortars containing 20%, 40%, 60% and 80% of fly ash have shown that fly ash has a long-term positive effect which might be related to a pozzolanic activity. The L3 binder consisting of 60% of coal fly ash and 40% lime has a higher compressive strength than the others. The binder setting start time is greater than that of cement but shorter than that of lime. The study of the thermophysical properties of the L3 binder shows that it has a higher thermal resistance than cement mortar. Moreover, it heats up less quickly because of its low effusivity compared to that of the latter. This analysis highlighted the principal characteristics that must be taken into account to use coal fly correctly in lime-based materials.

On the significance of interfacial chemistry on the strength of fly ash-cement composites

Despite the large number of studies on supplementary cementitious materials, the underlying physicochemical interfacial processes that govern their strength remain obscure. To address this knowledge gap, this paper strives to establish a relation between the chemical composition of fly ash (FA) at the molecular level and the macroscopic compressive strength in cement hydrates-FA composites. We develop a multiscale modeling framework that links the fundamental physicochemical attributes of calcium silicate hydrate (C-S-H)-FA interfaces across molecular (~1 nm), mesoscopic (~100 nm), and microscopic (~10 μm) length scales. We observe that FA's chemical composition affects the interfacial properties across all scales. FAs with higher network-modifier cation concentration show stronger molecular and mesoscale interfacial properties and statistically significant higher macroscopic compressive strength. This is particularly interesting for Class F FA, where early-age reactivity is negligible.

Comparison of Fly Ash Based (AAC) Block and Clay Bricks for Structure and Strength Properties

Fly Ash, a waste product collected from precipitators of coal based thermal power plants can be utilized as a potential resource as construction material. Fly ash, being fine light weight silica particles can cause environmental pollution if not managed properly, and/or not utilized as construction material. Fly ash can be used along with cement, cementitious materials to develop bricks and blocks which possess good properties for civil engineering structures. This paper presents comparative analysis of clay bricks and fly ash based autoclaved aerated concrete (AAC) block properties, methodology, process and material required for preparing fly ash based AAC block as per Indian standard code provisions, inspection and quality control. The textures of the blocks with fly ash were very similar to that of clay bricks; the sample with the additive contains spherical fly ash particles. These fly ash particles led to reduction in the density of the blocks and a substantial improvement in their durability. Use of this additive could have practical implications as a means of recycling and for achieving cost savings in blocks production. The structural cost, cement mortar for plaster & masonry, breakage, construction speed, quality, fitting & chasing, carpet area, availability, energy saving, chemical composition of fly ash based AAC blocks compared with normal clay bricks that delivered good results. From the present study, it can be concluded that fly ash based AAC blocks can be used as an alternative to clay bricks because of their strength, uniformity and smooth surfaces and lower cost. The cost of fly ash-based blocks was found about 20-35 % lesser than the clay bricks.

Production of ceramic glass foam of low thermal conductivity by a simple method entirely from fly ash

Ceramic glass foam/foams (CGF) from two different F-class fly ashes were produced via a well-known simple conventional sintering method using sodium silicate (Na2SiO3) as a foaming and fluxing agent. The research aimed to understand the effects of each fly ash, Na2SiO3 ratio, and sintering conditions on the properties and microstructure to produce a commercial CGF of low thermal conductivity. The chemical composition of fly ash from the thermal power plants of Tunçbilek and Seyitömer were quite similar but had different melting temperatures and microstructures. While the foam structure was successfully obtained at 1100 °C with 30 wt.% Na2SiO3 from Tunçbilek fly ash, a similar structure was obtained at 1150 °C from the Seyitömer fly ash. The effects of Na2SiO3 content and sintering temperature on the properties and microstructure of the CGF from the Tunçbilek fly ash of a lower melting point, in particular, were investigated systematically. The optimal sintering temperatures were determined to be 1200, 1150, and 1100 °C at the highest fly ash ratios of 90, 80 and 70 wt.%, respectively. The CGF were produced with 69.76–75.43% porosity, 0.55–0.69 gr/cm3 bulk density, 3.2–5.35 MPa compressive strength and 0.10–0.21 W/(m K) of low thermal conductivity. XRD results showed that optimal CGF samples mainly contained spinel, quartz and hematite crystal phases and amorphous phase. In this research, a thermal insulation material was successfully produced using an industrial waste completely with a well-known simple method. It is thought that this will contribute beneficially to the environment and the economy.

Using glass content to determine the reactivity of fly ash for thermodynamic calculations

Thermodynamic models for the hydration of ordinary portland cement (OPC) typically predict the composition of the resulting pore solution and the hydrates well. However, predictions for cementitious systems containing OPC and supplementary cementitious materials (SCM) are more challenging. The bulk chemical composition of fly ash does not sufficiently reflect the reactive portion of the material, as the crystalline components of fly ash do not generally react in cementitious systems. Thermodynamic modeling inputs using only the bulk chemical composition of fly ash overestimate the extent of both pozzolanic and hydraulic reactions. Two additional approaches are presented to overcome this limitation. In the first approach, the maximum reactive fraction of fly ash is computed by multiplying each bulk phase of the fly ash by a degree of reaction (DoR*) that is measured experimentally through calorimetric methods. In the second approach, the reactive (glass) fraction of the fly ash is determined to calculate its reactivity. In this alternative approach, the fraction of crystalline oxides measured using quantitative x-ray diffraction (QXRD) is subtracted from bulk oxide content determined using x-ray fluorescence (XRF) to establish a degree of reaction for each phase (DoRph*) to be used in the determination of the thermodynamic modeling inputs. Thermodynamic modeling predictions substantially improve by incorporating fly ash reactivity into the calculations using either the DoR* or DoRph*. The calculation of the reactive phases of fly ash using QXRD and XRF data serve as a potential alternative to the current calorimetric methods to calculate reactivity.

Use of Natural Pozzolanic Material as Partial Replacement Ordinary Portland Cement (OPC) in Concrete

Fly ash is a powder material of burned coal from thermal power stations which produces cementitious and pozzolanic material. Commonly use of fly ash in concrete for building construction contributes conducive environmental and also reduces the effect of pollutant in site project. Therefore, this study was conducted to investigate the use of fly ash as partial replacement of cement in concrete as a mean of producing more environmental friendly concrete. The content of fly ash as partial replacement of ordinary portland cement(OPC) is investigated by weight accordingly in range 0%(without fly ash), 10%, 20% and 30% for grade 25. The chemical composition of fly ash was determine using X-ray Fluorescence (XRF). The scanning electron microscope (SEM) was used to determine particle size, shape and texture of fly ash. The mix proportion of concrete was determine using mix design method according to British Standard. The workability of the fresh concrete mixture was evaluated using slump test while compressive strength of cubes concrete was evaluated at 7, 14, 28 and 56 days. A total of 48 cubes concrete with size 100mmx100mmx100mm were made. The optimum compressive strength at all ages of testing was obtained at 10% replacement. Workability decreased with an increased in replacement percentage of fly ash. The results therefore show that fly ash as pozzolanic materials can be used to partially replace ordinary portland cement in production of concrete.

Influence of Fly Ash Properties on Characteristics of Manufactured Angular Fly Ash Aggregates

This paper presents the influence of fly ash properties on angular fly ash aggregate (AFAA) and its manufacturing process to be used as a replacement of natural aggregate in concrete. Characteristics of fly ash play an important role in quality of AFAA as fly ash is the major constituent of the raw materials that are used in manufacturing of AFAA. Ample of studies have already been done on production and utilization of round fly ash aggregate (FAA) by pelletization process, but this study deals with innovative work of manufacturing of AFAA by crushing sintered briquettes into required sizes. Unlike round fly ash aggregate, AFAA possesses rough surface that enhance interlocking of these aggregate with paste in concrete. Four different types of AFAA were manufactured in laboratory by using two different samples of fly ash and two different binders. Performance of AFAA showed that specific surface area and chemical composition of fly ash affects sintering behavior of ash and as a result internal microstructure of aggregate also gets affected. Later, eight types of concrete were produced using four types of manufactured FAA at two different water cement ratio 0.45 and 0.50. It was concluded that strength of concrete depends on properties of manufactured AFAA and nature of bond between cement and aggregate at Interfacial transition zone. AFAA used concrete is found to be lighter in weight compared to the concrete of natural aggregate and is economical for use in construction purposes which in turn can save our depleting natural resources and environmental pollution.

Fly ash of thermal power plant - micro fill for hydro technical concrete

The article presents the option of using ash - fly ash of the New-Angren Thermal Power Plant (NATPP) as micro filler of a raw mix of hydraulic concrete, as the most appropriate solution to the economic and environmental problems of the Tashkent region, Republic of Uzbekistan. The total amount of utilized ash and slag waste for the 9th month of 2019 is 45,630 tons, ash disposal 2554 tons in the NATPP. These figures show that, annually, only 12-13% of ash and slag waste is used by consumers for various purposes, the remaining 87-88% of ash and slag waste accumulate in ash and slag dumps and pollute the environment of the region. The chemical composition of fly ash as a part of the raw mix of hydraulic concrete was studied, in comparison with the chemical composition of Akhangaran cement grade M400, its physical and mechanical properties were determined. We have carried out several laboratory experiments, we obtained a quantitative dependence of the effect of the ash-cement ratio on cement consumption to obtain hydraulic concrete of the required strength. According to the test results, it was found that the heat of hydration released during the setting process decreases in proportion to the ash content. This property is of great interest when concreting massive hydraulic structures in the hot season. Experiments show that when replacing part of the cement with fly ash on the first day, the set of strength slows down, and after 7 days it accelerates by 12-15%. With the use of fly ash in an amount of 40% by weight of Portland cement of grade 400, heat dissipation during hydration is reduced by almost 30-35%, which is very important for hydraulic concrete, which increases crack resistance and resistance in an aggressive environment. Summarizing the above, it can be concluded that the use of large-tonnage fly ash of the NATPP in concrete technology is a big state task, solving the priorities of the further development of the national economy and one of the strategic ways to solve the environmental problem in the NATPP zone.

Cenospheres characterization from Indonesian coal-fired power plant fly ash and their potential utilization

Abstract This study presents the cenospheres formation based on the characteristic of the fly ash and the coal as well as the potential production of cenospheres from fly ash from six coal-fired power plants in Indonesia. For cenospheres characterization, SEM-EDS, petrography analysis, and particle analyzer distribution were applied through all samples. Coal and fly ash chemical composition were analyzed using proximate analysis and ICP-MS. Based on the characterization of cenospheres and fly ash chemical components, we correlate the concentration of SiO2, Al2O3, SiO2/Al2O3, Fe2O3, Fe2O3+TiO2, CaO, MgO in the fly ash with cenospheres yield and diameter. The cenospheres yield in six Indonesian coal-fired power plant fly ash is in the range of 0.04–0.16% and inline with the ash content in the initial coal. Moreover, it was found that the cenospheres yield and diameter are in positive correlation with the concentration of SiO2 and Al2O3 in the fly ash, but they are in vice versa correlation with other chemicals. Ternary diagram of the cenospheres was made to their potential application and found that most of the cenospheres are in the ferrocalsialic.