Chemical Properties Of Fly Ash Research Articles

Effect of recycled aggregates with different parent strength and fly ash on flexural strength of recycled aggregate concrete prisms

Fast consumption of conventional ingredients of concrete and waste generated due to demolishing old buildings is a multi-fold problem in the concrete industry. Hence the sustainable alternative of it is the need of the day. In this research work effect of binary blending of demolished waste and fly ash on the flexural strength of plain concrete prism is presented. The properties of aggregates and cement are evaluated. The physical and chemical properties of fly ash were determined. Recycled aggregates from demolished waste with different mix ratios (1:2:4 and 1:1.5:3) were used. Optimization of recycled aggregates; by evaluating concrete cylinders in 12 batches; showed 35% as optimum. At the optimum dosage of recycled aggregates fly ash was used from 2.5% to 15% with an increment of 2.5% to optimize its dosage. Compressive strength test of the standard-size cylinders and their comparison with control concrete showed a 10% dosage of a fly as the optimum percentage to replace the cement in the concrete matrix. Using both optimized dosages of recycled aggregates and fly ash prism specimens of900mmx150mmx300mm were cast in four batches. The beam specimens were cured for 28 days followed by an evaluation of flexural strength and deflection under centric load in the universal testing machine. Test results of flexural strength (only 15% loss) showed good potential for both waste materials in the concrete matrix. Recycled aggregate with higher parent strength showed better performance than its other counterparts. With higher-strength recycled aggregates residual flexural strength was recorded as equal to 93%. For all specimens recorded deflection was within the allowable limits of ACI-318.

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

Ecophysiological response of Populus alba L. to multiple stress factors during the revitalisation of coal fly ash lagoons at different stages of weathering.

The enormous quantities of fly ash (FA) produced by thermal power plants is a global problem and safe, sustainable approaches to reduce the amount and its toxic effects are still being sought. Vegetation cover comprising long-living species can help reduce FA dump-related environmental health issues. However, the synergistic effect of multiple abiotic factors, like drought, low organic matter content, a deficit of essential nutrients, alkaline pH, and phytotoxicity due to high potentially toxic element (PTE) and soluble salt content, limits the number of species that can grow under such stressful conditions. Thus, we hypothesised that Populus alba L., which spontaneously colonised two FA disposal lagoons at the 'Nikola Tesla A' thermal power plant (Obrenovac, Serbia) 3 years (L3) and 11 years (L11) ago, has high restoration potential thanks to its stress tolerance. We analysed the basic physical and chemical properties of FA at different weathering stages, while the ecophysiological response of P. alba to multiple stresses was determined through biological indicators [the bioconcentration factor (BCF) and translocation factor (TF) for PTEs (As, B, Cr, Cu, Mn, Ni, Se, and Zn)] and by measuring the following parameters: photosynthetic efficiency and chlorophyll concentration, non-enzymatic antioxidant defence (carotenoids, anthocyanins, and phenols), oxidative stress (malondialdehyde (MDA) concentrations), and total antioxidant capacity (IC50) to neutralise DPPH free radical activity. Unlike at L3, toxic As, B, and Zn concentrations in leaves induced oxidative stress in P. alba at L11, shown by the higher MDA levels, lower vitality, and reduced synthesis of chlorophyll, carotenoids, and total antioxidant activity, suggesting its stress tolerance decreases with long-term exposure to adverse abiotic factors. Although P. alba is a fast-growing species with good metal accumulation ability and high stress tolerance, it has poor stabilisation potential for substrates with high As and B concentrations, making it highly unsuitable for revitalising such habitats.

Characteristics of Fly Ash and its Influence on the Germination of Amaranthus Seeds

The physical and chemical properties of fly ash collected from three different thermal power stations were studied and the fly ash with neutral to alkaline pH was utilized as a medium for the germination of amaranthus seeds. The germination test was carried out using a completely randomized design with two replications at Agricultural College and Research Institute, Madurai. The various fly ash was analyzed for its physical and chemical properties with standard methods. The fly ash with a slightly alkaline pH was selected and media was prepared with soil, vermicompost and farm yard manure. The seeds of an amaranthus crop were sown and the germination percentage, days to germination, shoot length, root length and vigour index were recorded. The collected fly ashes were recorded with low bulk density, alkaline pH with quantities of micro and macronutrients. The fly ash of Tuticorin has a slightly alkaline pH (8.03) and was utilized for media preparation. Among the different media, the media with treatment Fly ash + Soil + Vermicompost (1:1:4) + Bio Fertilizer has recorded higher germination percentage, shoot length, root length, vigour index, lower days to germination with 94.6%, 18.3 cm, 4.8 cm,16.17 and 2.8 respectively. The vermicompost is best for the enrichment of fly ash compared to farm yard manure as it is completely decomposed organic manure.

A novel approach to the dry desulfurization process by means of sodium bicarbonate: A full-scale study on SO2 emission and geochemistry of fly ash

The application of Dry Sorbent Injection (DSI) desulfurization with sodium bicarbonate was investigated to reduce SO2 emission from power sector. The sorbent was injected directly into the combustion chamber of the 29 MWth grate boiler, into a non-standard area of high temperature (approximately 700 °C), while generally the DSI method is carried out in the flue gas duct with a temperature below 250 °C. Unique nozzle design for injecting powdery sorbents was implemented and two stoichiometric ratios were tested: NSR = 1.1 and NSR = 3.0. The reduction of SO2 from a base level of 1580 mg SO2/Nm3 to 301 mg SO2/Nm3 at 6% O2 was achieved, resulting in a process efficiency of 81%. The chemical properties of fly ash were determined in terms of its safe storage and potential use according to the principles of the circular economy. Ash formed during the desulfurization process shows a different chemical composition than the reference sample. A significant increase in the concentrations of the following components and parameters was indicated: S, Na, Zn, Cu, As, Mo, Pb, loss of ignition (LOI) and total organic carbon (TOC). The change in chemical composition led to an increase of total dissolved matter (TDS) in water leachate as well as sulphates, chlorides, fluorides, As, PB, Cu and Zn concentrations.

Low Temperature Thermal Treatment of Incineration Fly Ash under Different Atmospheres and Its Recovery as Cement Admixture.

Municipal solid waste incineration fly ash is classified as hazardous waste because it contains dioxins and a variety of heavy metals. It is not allowed to be directly landfilled without curing pretreatment, but the increasing production of fly ash and scarce land resources has triggered consideration of the rational disposal of fly ash. In this study, solidification treatment and resource utilization were combined, and the detoxified fly ash was used as cement admixture. The effects of thermal treatment in different atmospheres on the physical and chemical properties of fly ash and the effects of fly ash as admixture on cement properties were investigated. The results indicated that the mass of fly ash increased due to the capture of CO2 after thermal treatment in CO2 atmosphere. When the temperature was 500 °C, the weight gain reached the maximum. After thermal treatment (500 °C + 1 h) in air, CO2, and N2 atmospheres, the toxic equivalent quantities of dioxins in fly ash decreased to 17.12 ng TEQ/kg, 0.25 ng TEQ/kg, and 0.14 ng TEQ/kg, and the degradation rates were 69.95%, 99.56%, and 99.75%, respectively. The direct use of fly ash as admixture would increase the water consumption of standard consistency of cement and reduce the fluidity and 28 d strength of mortar. Thermal treatment in three atmospheres could inhibit the negative effect of fly ash, and the inhibition effect of thermal treatment in CO2 atmosphere was the best. The fly ash after thermal treatment in CO2 atmosphere had the possibility of being used as admixture for resource utilization. Because the dioxins in the fly ash were effectively degraded, the prepared cement did not have the risk of heavy metal leaching, and the performance of the cement also met the requirements.

Treatment of Comprehensive Wastewater from Chemical and Pharmaceutical Parks by Fly Ash-Coated Iron Electrode Electrocoagulation

With the rapid development of the economic system and the continuous development of industry, environmental pollution is becoming more and more important, so wastewater treatment urgently needs to be strengthened. This article uses fly ash-coated iron electrode electrocoagulation method to carry out experimental tests on the treatment of comprehensive wastewater from chemical and pharmaceutical parks. Fly ash is used as a raw material to prepare a shaped adsorbent; in order to analyze whether the adsorbent has many potential applications in actual wastewater treatment and use. The experiment research of iron electrode electrocoagulation was carried out on actual groundwater, aiming to provide data and theoretical support for the utilization of fly ash and the optimization of comprehensive wastewater treatment technology. The article mainly conducts related research on title distribution, firstly the physical and chemical properties of fly ash, and secondly, discusses the related structure of electrocoagulation method, and solves the problem of comprehensive wastewater based on the combination of the two solving issues. Aware of the importance of sewage treatment and the characteristics of related treatment methods such as adsorption, membrane separation technology, and ion exchange, the advantages of these methods are also used for reference in subsequent experiments to achieve the purpose of reliable experimental results. The experimental results show that the effect of sewage treatment with fly ash with different average diameter particles is obvious. Among them, the maximum value of vibration grinding ash before and after application increased from 5.62 to 8.31, and the maximum removal rate is also 8.31; the removal effect is significant. It can be seen that the fly ash-coated iron electrode electrocoagulation method can have a great effect on the treatment of comprehensive wastewater in the chemical and pharmaceutical park.

Ecological Risk Assessment and Influencing Factors of Heavy-Metal Leaching From Coal-Based Solid Waste Fly Ash.

In order to promote and broaden the utilization of fly ash as a resource, the fly ash from a 2,660-MW coal-fired power plant in Huainan (China) was investigated. The physical and chemical properties of fly ash were characterized by scanning electron microscopy, energy spectrum analysis, and XRD. The content and different forms of the heavy metals Cd, Cr, Cu, Co, and Ni were determined by acid digestion, oscillation leaching, and Tessier five-step extraction. The effect of pH, temperature, and particle size on the leached amount of heavy metals was studied. Finally, the ecological risk index was calculated for each heavy metal via the risk assessment coding (RAC) method and Hakanson ecological risk assessment method, allowing the ecological risk of fly ash to be determined under different environmental conditions. Results showed that the average concentrations of Cd, Cr, Co, and Ni were all below the risk screening values reported for environmental pollutants (pH > 7.5). Under varying pH, temperature, and particle size conditions, the leached amounts (oscillation leaching) were below the soil risk screening values for agricultural land in China. An RAC-Cd value of >50% indicates a high ecological risk, while the RAC values of Co and Ni were between 10 and 30%, indicating a medium ecological risk, and the RAC values of Cr and Cu were <10%, indicating a low ecological risk. With increasing pH, the potential ecological risk index (RI) decreased, with a maximum RI of 59.62 observed at pH 2.8. With increasing temperature, the potential ecological RI increased initially to a maximum of 27.69 at 25°C and then decreased thereafter. With increasing particle size, the ecological RI decreased, with the highest RI of 4.06 occurring at <0.075 mm. The Hakanson ecological RI value was below 150, indicating a slight ecological risk. Therefore, fly ash can be considered as a soil additive and conditioner that is suitable for use in the improvement of reclamation soil in coal mining subsidence areas.

Study on the Characteristics of Grinding Activation of Fly Ash and Its Influence on Cement Cementitious System

This study takes fly ash of a coal-fired power plant as the research object, the pulverized and activated fly ash was processed by ball milling process. The difference of physical and chemical properties of fly ash before and after pulverized and activated treatment and its influence mechanism on cement cementitious system were studied by a series of characterization analysis methods. The results show that pulverized fly ash activation significantly reduces the particle size of fly ash, increases its specific surface area, and decreases the crystallinity of crystal minerals and anionic polymerization degree of internal silicon aluminate substance in fly ash, thus reaching the deep activation effect of fly ash activity. Fly ash powder can promote the compressive strength of test block more than fly ash original ash, especially the early compressive strength of test block. The experimental results of water absorption and thermogravimetry show that the effect of fly ash powder on test block is mainly to improve the compactness of test block, reduce its porosity. At the same time, accelerating the secondary hydration reaction of cement is bound to produce more C–S–H gel, thus improving the mechanical properties of test block.

Coal Power Plant Fly Ash Characterization Assessment for Geopolymerization Process

This paper presents the physical and chemical properties of fly ash obtained from two coal power plants; the Sultan Salahuddin Abdul Aziz Power Plant in Kapar, Selangor and Sultan Azlan Shah Power Plant in Manjung, Perak. Moisture and radionuclide contents, and chemical composition in the fly ash were characterized. It was found that moisture content for Kapar and Manjung fly ash were at 0.41% and 0.11%, respectively. XRF result showed that Kapar fly ash sample is of class C due to the total percentage of SiO2, Al2O3, and Fe2O3 being less than 70% while Manjung fly ash sample is of class F due to the total percentage of SiO2, Al2O3, and Fe2O3 of more than 70%. Gamma spectrometry analysis indicated presence of 226Ra, 232Th, and 40K in the samples. These data can be used to establish a technical standpoint in supporting the development of radioactive waste immobilization technology using geopolymer material. This study is expected to benefit the nuclear fuel cycle specifically in conditioning of low-level radioactive waste produced in nuclear power plants.

Physico-Chemical Properties of Fly Ash and Its Applications in Agriculture Field

The Physical properties of fly ash is depending upon the coal type, boiler type, ash content in coal, combustion method and collector setup. The factor affecting or influencing the physical properties are also responsible for wide variation of chemical properties of fly ash. Two types of fly ash are generated in the thermal power plants; it is also contain micro and macro nutrients, required for growth of plants. Quality of soil is affects the growth of plant, due to low pH of soil plant growth has been affected, it is minimizing with external addition. Fly ash has many micro and macro nutrients with application of fly ash in soil pH of soil becomes controlled.

An Assessment of the Phytoremediation Potential of Planted and Spontaneously Colonized Woody Plant Species on Chronosequence Fly Ash Disposal Sites in Serbia-Case Study.

In this study, the potential of planted (Tamarix tetrandra Pall. ex M.Bieb. and Robinia pseudoacacia L.) and spontaneously colonized (Amorpha fruticosa L. and Populus alba L.) woody species for the phytoremediation of potentially toxic trace elements (TEs) such as As, B, Cr, Cu, Mn, Ni, Se, and Zn, from the chronosequence fly ash (FA) deposit lagoons (L1 and L2) at the ‘Nikola Tesla A’ Thermal Power Plant (TENT-A) in Serbia were analyzed. The differences in the pseodototal and bioavailable (DTPA-extractable) concentrations and mobility (AR index) of TEs in FA at the examined lagoons are a result of the time-conditioned influence of weathering (3 and 11 years respectively) and vegetation development on changing the basic physical and chemical properties of FA (texture, pH, EC, CEC, C, N, and bioavailable P and K) and its toxicity. This resulted in differences in the concentration of TEs in the roots and leaves of the examined plants at L1 and L2. All examined species accumulated Cr the most in the root (BAF > 1 and TF < 1), which suggests that they are good stabilizers of this element. Biological indices for As (BAF > 1 and TF < 1) identified T. tetrandra and A. fruticose as good stabilizers of As. P. alba stood out as accumulating the highest levels of B, Ni, and Zn, T. tetrandra the highest levels of Cu, Mn, and Se, and R. pseudoacacia the highest levels of As and B in leaves (BAF > 1; TF > 1), which makes them good extractors of these elements from the FA at TENT-A. However, due to toxic concentrations of As, B, Se, and Zn in their leaves, they are not recommended for the phytoremediation of the investigated lagoons through the process of phytostabilization. Under conditions of elevated total Cu and Ni concentration in FA, the content of these elements in the leaves of A. fruticosa at both lagoons were within the normal range. This, in addition to a good supply of essential Zn, the stabilization of As and Cr in the roots, an increase in BAF, and a decrease in TF for B with a decrease in its mobility in ash over time, singles this invasive species out as the best candidate for the phytostabilization of TEs in FA at the TENT-A ash deposit site.

Characterization and evaluation of sudanese fly ash as partial replacement for cement in concrete mixes

The main objectives of this paperare to characterize the physical and chemical properties of the locally produced fly ash,to study its suitability to be utilized in concretemixes and to determine the degree of its pozzolanicity .Physical and chemical properties of fly ash were tested according to the standards of the American Society of Testing and Materials (ASTMC311-02). Fly ash was tested for density, fineness, moisture, Loss on Ignition (LOI), chemical composition, X-ray Fluorescence test (XRF), X-ray Diffraction test (XRD) and strength test. The results were then compared with the ASTM C618-03.It was found that the locally produced fly ash contains high level of silica, hence it can be classified, based on its chemicalcomposition, as class F fly ash; this may be probably due to the addition of sand applied in the combustion chamber. TheXRD showed that it contained crystalline form of silica which is not good for the use in concrete. On the other hand, thestrength test proved that there was a degree of strength and pozzolanicity obtained. The strength activity index of 28-daywas found 70%.This may be due to presence of amorphous silica within the crystalline one.

Advances in Fly Ash Based Geopolymer

The current research on the resource utilization of fly ash is summarized, the physical and chemical properties of fly ash and some of the research results of fly ash based geopolymers in resource utilization are introduced, the current situation of the application of fly ash geopolymers is discussed, and the main problems and development trends in high-value utilization are analyzed.

Pozzolonic activity and strength activity index of bagasse ash and fly ash blended cement mortar

Abstract Assessment of Pozzolonic activity of certain industrial waste is important due to an increasing need of cementitious material. This study was undertaken to widen the scope of using pozzolanic waste like fly ash and bagasse ash as a supplement to cement. Sugarcane bagasse ash (BA) is a solid waste obtained from the cogeneration combustion boilers in sugar industry and fly ash (FA) is a waste product generated during coal combustion in thermal power plants. The present study is an attempt to determine the pozzolanic activity of BA and FA. Physical properties such as particle size, surface area and specific gravity of ordinary Portland cement (OPC), Sugarcane bagasse ash and fly ash were determined using HORIBA zeta analyzer, BET surface area analyzer and Standard Le-chatelier flask respectively. The chemical composition of OPC, BA and FA was obtained using X-ray florescence (XRF) and the mineralogical analysis was carried out using X-ray diffraction (XRD) technique. Frattini test was conducted to determine hydroxyl ion (OH–) concentration and calcium ion concentration (Ca+2) which is represented through solubility curve. Strength activity index (SAI) was based on the compressive strength test performed on mortar cube specimen which were cast by partial replacement of cement with bagasse ash and fly ash at 10, 20 and 30 percent by weight. The SAI for both BA and FA blended cement mortar was determined after 3, 7, and 28 days of curing and the results compared. The physical and chemical properties of FA and BA meet the requirements as a Pozzolonic material, based on the mineralogical analysis and strength activity index, blending OPC with 20 percent FA or 10 percent BA is beneficial.

An overview of the properties of sustainable concrete using fly ash as replacement for cement

Many industries produce several types of by-products in a large amount each year which is negatively affecting the environment by compromising human health and depleting the natural resources. Utilisation of such industrial by-products in the construction field has become an important step to address the environmental problems as well as to solve the waste disposal crisis. Fly ash (FA) is one of such by-products obtained from pulverised coal combustion in thermal power plants. FA can be utilised as substitution or addition of cement in making cement-based products. This paper critically analyses and summarises the influence of FA on characteristics of concrete. The physical, chemical properties of FA and its hydration reaction mechanism have been addressed in the present study. The influence of FA on the fresh and hardened properties such as workability, compressive and tensile strength, modulus of elasticity and durability characteristics like resistance to abrasion, permeability, chloride penetration, carbonation, sulphate attack and alkali silica reaction, freezing and thawing effect and shrinkage in concrete have been reviewed in this paper.

배기가스 조성에 따른 활성탄의 수은 흡착 특성

Activated carbon injection upstream of a particulate matter control device is a widely applied method for the control of mercury emission from the coal-fired plant and waste incinerator. Performance of activated carbon in mercury control depends on various factors such as flue gas composition, physical and chemical properties of fly ash and activated carbon, etc. This study was designed to investigate the effect of flue gas composition on the mercury adsorption efficiency of activated carbon. Commercial activated carbon was obtained, and a fixed-bed reactor system was used for the tests of its mercury adsorption at various simulated flue gas conditions. A baseline gas consists of 12% carbon dioxide (CO₂), 5% oxygen (O₂), 7% water vapor (H₂O), 60∼70 μg mercury (Hg)/m³ and balance nitrogen (N₂). Each of acidic gases such as sulfur dioxide (SO₂), nitrogen monoxide (NO) and hydrogen chloride (HCl) was added to the baseline gas and injected for the test to investigate the effect of each acidic gas on the mercury adsorption efficiency of activated carbon. In addition, the mercury adsorption efficiency of activated carbon was examined at the conditions of simulated flue gas (1) before air pollution control (2) after desulfurization and (3) after nitrogen oxides (NOx) control.

The study of fly ash filler behaviour in the polymer matrix of polyethyleneterephthalate

The purpose of the investigation was to study the behavior of mechanically activated fly ash filler containing carbon in a polymer matrix of polyethylene terephthalate (PET). By means of the methods of optical and electron microscopy the change of physical and chemical properties of fly ash after intensive grinding in planetary mills of centrifugal type was considered. The research showed that mechanically activated filler, in contrast to its non-activated analog, structures the polymer matrix and provides improving the characteristics of the composite material.

Influence of Milling on some Chemical Properties and Reactivity of CFBC Fly Ash

This paper describes influence of milling on chemical properties of fly ash from Circulating fluidized Bed Combustion (CFBC). Specific properties of fly ash was determined using calorimetric measurement. It was determined heat properties and total content of calcium oxide CaO. The following methods of measurement were also performed: granulometric measurement and chemical analysis. The ash properties of non-milled and milled ashes were also described and evaluated and the ash reactivity was compared.

Microstructural modelling of the strength of mortars containing fly ash using µic

Although it is well known that the physical and chemical properties of fly ashes play an important role in microstructural development, models that explicitly simulate the effects of these properties on the performance of pastes and mortars are not available. The process of hydration in cement pastes containing 10 different fly ashes was simulated in a microstructural model. In this model, it was possible to explicitly include the effect of the particle size distribution and composition of cements and fly ashes. It was found that the strength of mortars measured in the laboratory correlated well with microstructural properties calculated from the simulations, including the effects of the physical and chemical properties of cements and fly ashes. The results show that although the strength development of mortars containing various cements and fly ashes can be predicted using models, the properties of hydration products in the presence of fly ash have to be considered to be different than when without fly ash in order to explain strength development observed in mortars.