Waste Fly Ash Research Articles

Karakteristik Beton Mutu FC 30 Dengan Menggunakan Limbah Peleburan Baja (Slag) Dan Pembakaran Batubara (Fly Ash)

The use of slag and fly ash waste for building materials is not optimal, because it contains heavy metal oxides. With the issuance of Government Regulation no. 22 of 2021, dust resulting from burning coal from Steam Power Plants and other activities is not included as B3 waste. With research on the use of fly ash and slag to increase the compressive strength of concrete, research was carried out in the laboratory to determine the optimal composition for the use of slag and fly ash as a substitute for coarse aggregate and cement in concrete mixtures. By testing in the laboratory, results were obtained with variations in slag. 10, 20% and 30% with fly ash remaining at 10% as a concrete mixture by comparing with a normal concrete mixture. From the test results, the results obtained were that the addition of slag and fly ash waste could reduce the heat of concrete at FC 30, producing concrete compressive strength close to normal concrete compressive strength, namely 26.31 MPa for 7 days, 33.11 MPa at 28 days, and 39.61 MPa at 56 days with composition10% slag and 10% fly ash with the slump value achieved was 6 cm which makes it difficult to make concrete. The addition of 20% and 30% slag with 10% fly ash produces a compressive strength of concrete that is lower than the concrete compressive strength of FC 30. The appropriate composition to use is 10% slag as a substitute for coarse aggregate and 10% fly ash as a cement substitute

Solidified lake sediment with industrial waste and construction waste used as barrier cover material: mechanical strength, water resistance performance, and microscopic analysis

ABSTRACT This study introduces a novel landfill cover material, employing lake sediment as a substrate, stabilised with fly ash, slag, desulfurisation gypsum and construction waste. The mechanical properties, including shear strength parameters, unconfined compressive strength, hydraulic conductivity, volumetric shrinkage, and water content, of the solidified sludge were evaluated. The microscopic mechanism of the solidified sludge were investigated through XRD, FTIR, and SEM-EDS techniques. A novel three-layer composite capping cover system for landfills is proposed, comprising an upper capillary barrier layer, a middle drainage layer and a bottom impermeable layer . Indoor rainfall simulation tests were conducted to assess the water retention performance of this capping cover system under repeated moderate, heavy, and torrential rainfall events. The early strength of the solidified sludge exhibited rapid development, with cohesion and internal friction angle reaching 382.56 kPa and 57.67°, respectively, after 3 days. After 28d, the unconfined compressive strength ranged from 6.93 to 14.29 MPa, with hydraulic conductivity between 3.98–23.1 × 10−8cm/s. The hydration reactions of the industrial waste residues resulted in the formation of Ettringite, Gypsum, and hydrous calcium (aluminum) silicates. The Ettringite and Gypsum crystals formed an internal support framework, while the generation of gel-like substances such as C-S-H and C-A-S-H facilitated product aggregation. The RSM was employed to optimise the material ratio of the solidified sludge, while the Pearson coefficient facilitated correlation analysis. This study provides valuable data for designing landfill solidified sludge cover systems and offers a new approach for the co-disposal of sludge and industrial waste.

Utilization of asphalt waste Dust and fly ash for sustainable mortar

Utilization of asphalt waste Dust and fly ash for sustainable mortar

Transforming waste red mud and fly ash to wealth by designing a hybrid Al alloy composite with improved mechanical and tribological properties

AbstractIn the present work, we demonstrate the development of a cost‐effective hybrid composite of aluminium 6063 alloys by utilizing some industrial wastes like fly ash and red mud as reinforcement. Alloy composites have been produced with varying concentrations of reinforcement by a two‐step stir‐casting method. X‐ray diffraction (XRD) confirmed the presence of fly ash and red mud whereas microstructural analysis through optical microscopy showed a uniform distribution of the reinforcements within the alloy matrix. The composite formed with optimized weight fractions of red mud and fly ash exhibited higher ultimate tensile strength in comparison with base aluminium alloy. Furthermore, the dry sliding wear behaviour of the alloy and its composites have been investigated at low sliding speed against a hardened disk at three different loads (2 kg, 3 kg and 4 kg). The wear rate increases with increasing load in the alloy as well as in the composite. Sem images of worn surfaces of the hybrid composite exhibit fewer grooves when 5 wt.‐% of both reinforcements are present. Essentially, the overall wear rate of the composite is found lower than the base alloy. Hybrid composites with 5 wt.‐% of both reinforcements show maximum wear resistance.

The effect of travertine waste on the strength and insulation properties of foam concrete

Abstract Incorporating waste additives into foam concrete mixtures is a promising route to develop environmentally-friendly concrete production with tailored thermos-mechanical properties. In this paper, the effects of various fabrication parameters of foam concrete, including the type of waste additive, water/binder ratio, density of mixture, and incorporation of glass fibers were investigated. Foam concrete samples were fabricated using fly ash and travertine wastes, and the variations in their flexural strength, compressive strength, and thermal conductivity using various concrete mixture designs were measured. The obtained results show that foam concrete with fly ash additive tends to have higher compressive strength and thermal conductivity than foam concrete with travertine waste. However, the latter exhibits better thermal insulation properties, which tend to improve by adding glass fibers. This work defines the outlines for exploring the use of harmful wastes in fabricating foam concrete. It offers guidelines for developing improved foam concrete mixtures with tailored thermos-mechanical properties.

Sustainable biomass aerogel with enhanced thermal and mechanical properties by industrial waste fly ash: A simple route for the green synthesis

Sustainable biomass aerogel with enhanced thermal and mechanical properties by industrial waste fly ash: A simple route for the green synthesis

Synergistic removal of Hg0, HCl, and SO2 from flue gas in municipal solid waste incineration by mechanically modified fly ash.

The emissions of flue gas components (such as Hg0, SO2, HCl) and the generation of hazardous waste fly ash from municipal waste incineration pose a significant threat to environmental integrity. In this study, a mechanochemical method combined with a modifier is innovatively proposed for the modification of fly ash to remove Hg0. In the fixed bed adsorption experiment, the removal efficiency of up to 60 percent can be achieved by ball milling (700rap,30min) alone. The modification of fly ash by mechanical force coupling with pyrite can achieve Hg0 removal efficiency is increased to more than 90 percent. By taking advantage of the excellent adsorption capacity of modified fly ash for acidic gases, the enhancement of S and Cl∗ active sites on the surface of modified fly ash strengthened the removal efficiency of modified fly ash for Hg0. DFT simulations evidenced that the defective S sites caused by the ball milling process could enhance the adsorption capacity of pyrite for Hg0. The fly ash was modified with mechanically coupled pyrite and alkalis and was able to have good adsorption capacity for acidic gases, the highest removal effect reached 93.1% and 96.7% for SO2 and HCl, respectively. The adsorbed acid gases increased the S and Cl∗ active sites, which led to the removal of Hg0 from the modified fly ash to more than 94.4%, achieving the synergistic removal of acid gases and Hg0. This method can realize the integrated technical route of "Fly ash collection - Online modification - Timely injection". A novel investigation was conducted on the elimination of flue gas contaminants and the reutilization of perilous fly ash.

The Effect of Pozzolanic Material and Waste Foundry Sand on Fresh Mortar Properties and Prediction of Some Results by Artificial Neural Networks

Waste reuse is frequently included in scientific studies. As a result of the increase in production after the Industrial Revolution, this waste is increasing day by day. One of these wastes is waste casting sand used as molding sand in the casting industry. In this study, the effects of this waste and silica fume and fly ash, which are also waste materials, on fresh mortar properties were investigated. Different proportions of fly ash, foundry sand, and silica fume mixtures were used in the study. Spreading tests were carried out on the mixtures with mini v funnel and mini-slump funnel according to EFNARC. According to the experiments, we tried to determine the most suitable mortar mixtures in terms of workability with appropriate material selection. The effect of waste materials on workability has shown a positive development. It tried to determine the test results of some mixtures by modeling with artificial neural networks. The effect of water content in some mixtures was also analyzed, and it was concluded that a 0.3 w/b ratio was the most suitable. The cement dosage was kept constant at 800 kg/m3, and other variables were analyzed. The substitutions of pozzolanic materials were proportioned over the cement dosage.

Shedding Electrons on Cenospheres: Advancing Characterization Through X‐ray Micro‐Analysis

AbstractCenospheres are hollow spherical structures derived from coal fly ash waste. They exhibit unique properties such as thermal stability, lightweight composition, inertness, and energy attenuation, which make them ideal for advanced material applications. Due to their cost‐effectiveness and wide availability, they are viable alternatives to specialized micro‐ and nanospheres synthesis. However, the limited understanding of cenospheres and the complexities involved with characterization techniques hinder the utilization of their valuable attributes effectively. Our study introduces a novel methodology for classifying and characterizing cenospheres using X‐ray microanalysis coupled with energy‐dispersive X‐ray spectroscopy (EDS). Herein, we identify inherent X‐ray emission profiles for the cenospheres and solid spheres (which look similar to the untrained eye), enabling rapid classification through EDS line scans. Further, we establish a characterization threshold for the line scans, that is, half the penetration depth at 99% X‐ray intensity for specific accelerating voltages. We propose a non‐destructive technique for measuring the cell wall thickness and introduce error corrections for measurements at lower accelerating voltages. When using higher voltages, the measurement of cell wall thickness yields RMSE values of 0.41 for entering cell walls and 0.21 for exiting cell walls. These values provide specific measurements for the thickness of individual cell walls quantitatively rather than relying on more generalized theoretical relationships.

Analysis of Fly Ash and Sandblasting Waste Addition in Cementitious Composite Lawn Table Reinforced by Cocofiber and Wiremesh

Analysis of Fly Ash and Sandblasting Waste Addition in Cementitious Composite Lawn Table Reinforced by Cocofiber and Wiremesh

Influence of fly ash and waste tire rubber particles on mechanical and tribological properties of composite brake linings

AbstractTo investigate the influence of waste tire rubber (WTR) and fly ash (FA) on mechanical and tribological properties of composite brake linings, 8 different formulations of 8–40 wt% FA and 10–12 wt% WTR were selected. The mechanical tests showed that high amounts of resin and FA result in the highest hardness. The inclusion of WTR, decreased hardness and internal shear strength; however, increased the acetone extraction and resistance to coefficient of friction (COF) fluctuations. With the use of WTR, steady COF fluctuations with the temperature changes are achieved. The tribological properties were evaluated with both a drum‐type and disc‐type dynamometer by the SAE‐J661 standard. Reduced COF fluctuations were observed in <15 wt% FA and 10 wt% WTR containing samples. The highest COF was obtained for the 14 wt% FA and the lowest wear rate for the samples containing 8 wt% FA. The brake composites exhibited consistent COF in the range of 0.34–0.52, and wear rates lower than 7 wt%. Two compositions containing 40 and 25 wt% FA (no WTR), and one containing 10 wt% WTR and 8 wt% FA provided the best results. Finally, four best compositions were selected and worn surfaces were analyzed with SEM after full‐scale dynamometer tests.Highlights Three composites with high waste percentage were successfully manufactured Fly ash and waste rubber are used without any post‐processing to cut costs Waste rubber increased resistance to COF fluctuations with temperature change Full‐scale dynamometer tests are performed for friction and wear properties Worn surfaces were analyzed with SEM method

Application of waste fly ash and graphite powder used as backfill materials in vertical ground heat exchangers

Backfill material plays a significant role in heat transfer between the ground heat exchangers (GHEs) and surrounding soil. Fly ash is the fine ash wasted from coal combustion in thermal power plants, which may cause a serious of problems including air, water and soil pollution. To fully utilize the waste resources and improve the thermal performance of backfill material, a method of using waste fly ash and graphite powder is proposed, and the feasibility of using them as backfill material is investigated via laboratory and field test, in which the economic aspect is taken into consideration. The results indicate that the highest thermal conductivity of thermally enhanced backfill material could be increased to 2.391 W/(m·K) via laboratory test, with a growth rate of 23.69%, in which the mass ratio of graphite reaches 10% meanwhile guaranteeing the workability of fresh mortar. Heat transfer rates could be enhanced by 27.22% compared with traditional backfill material of natural sand via field test, corresponding to a highest heat transfer rate of 55.80 W/m. The economical value could be achieved through the lower cost of raw material and the reduction of drilling depth.

Ambient Pressure Carbonation Curing of Cold-bonded Fly Ash Lightweight Aggregate Using Coal-fired Flue Gas for Properties Enhancement and CO2 Sequestration

In the current CO2 curing process, pure CO2 gas with a concentration exceeding 99% is primarily used. However, flue gas, which typically contains 10-30% CO2, can also be utilized for carbonization. This study sought to explore the viability of employing flue gas for carbonation and assessed the impact of impurity gases such as SO2. Two typical industrial solid wastes (fly ash and coal gangue) were used to substitute a portion of the cement to prepare light aggregates, which were carbonized under varying concentrations of CO2 and SO2. The porosity and water absorption of the samples decreased after carbonation. A higher degree of carbonation was observed at increasing CO2 concentration. Aggregates carbonated with 15% CO2 improved the CO2 absorption by 48%. The actual CO2 uptake reached up to 58.3% of the theoretical value. The presence of SO2 has been found to impact the uptake of CO2. The CO2 uptake initially declined and then increased as the SO2 concentration increased. The existence of SO2 led to varied increases in the leaching concentrations of the aggregates following the process of carbonation, and some even exceed standard limits. In the presence of both CO2 and SO2, SO2 reacted with the aggregates, resulting in the creation of calcium sulfate. This reaction disrupted the structure of the aggregate, facilitating the diffusion of CO2 into the samples.

Enhanced mechanical properties and mechanism of iron ore tailings-based geopolymers modified by municipal solid waste incineration fly ash

Iron ore tailings, coal fly ash and municipal solid waste incineration fly ash (MSWI FA), as solid waste, must be disposed of. Iron ore tailings, coal fly ash and MSWI FA were successfully prepared into high-performance geopolymer. The compressive strength of optimal geopolymer reached 57.89 MPa. Based on XRD, FTIR, SEM and chemical extraction analysis, C-(A)-S-H was the main gel product along with N-A-S-H. It was found that the dominant hydration process of geopolymer was changed from diffusion process (D) to phase boundary reaction process (I) after MSWI FA addition based on hydration reaction rate curves and dynamic simulation, releasing more hydration heat and generating more C(N)-A-S-H gels. Heavy metal content in the optimal geopolymer was below the limits of Class I screening value of development land (GB 36600-2018). Ef and Cf of the optimal geopolymer were 30.9 MJ/ton/MPa and 6.88 kg CO2/ton/MPa, affirming the viability of utilizing iron ore tailings, coal fly ash and MSWI FA as raw materials for geopolymer production, which provides a promising collaborative resource method of processing them.

The effectiveness of fly ash and fly ash-cement mixtures as stabilizing materials for high plasticity clay

Abstract The increasing activity of burning coal as fuel for Steam Power Plants (PLTU) will increase the amount of fly ash waste, urging the industry to maximize waste utilizations as, for instance, a stabilizing material for high plasticity clay. This research examined the effectiveness of clay + fly ash and clay + fly ash + cement stabilization in increasing the strength of road subgrade. The results showed that fly ash and fly ash + cement improved clay properties, demonstrated by the value of unsoaked CBR (5.78%) and soaked CBR (3.11%) of unstabilized clay. Clay + 20% fly ash yielded optimum CBR value (23,13%), and stabilizing clay subgrade on a 50-meter section using 20% fly ash at a cost of IDR 18,329,675. The mix of 40% fly ash + 15% cement yielded optimal CBR value (42.70%) at a cost of IDR 18,359,435.00. The evaluation of soil properties and cost analysis, shows that the most efficient mixture variation is 40% fly ash and 15% cement for clay stabilization.

Strength Properties and Microscopic Experimental Study of Modified Sawdust Based on Solid Waste Synergistic Utilization.

Sawdust is the cutting tailings produced during stone processing, which is difficult to deal with and has a huge stock. Therefore, it is particularly important to enhance the comprehensive utilization of sawdust. The aim of this study was to synergistically utilize sawdust with other industrial wastes (fly ash, silt, and red mud), add cement as a curing agent to prepare modified sawdust, and analyze its performance through an unconfined compressive strength test, dry and wet cycle tests, and SEM. The results showed that the compressive strength of modified sawdust with different solid waste dosages was more than 2.5 MPa after 7 days of maintenance, the strength was basically more than 4 MPa after 28 days of maintenance, and 8% solid waste dosage had the best effect. In addition, the modified saw mud with 8% fly-ash dosage had superior wet and dry cycle resistance, with expansion and shrinkage lower than 0.5% and good stability. This study provides a new idea for the synergistic utilization of saw mud and other solid wastes, and it is recommended to consider 8% solid waste dosage to optimize the performance in practical applications.

Facile synthesis of layered spinel ferrite from fly ash waste as a stable and active ketonisation catalyst

Spinel catalysts exhibit superior activity and structural stability across a wide range of catalytic reactions. Nevertheless, few studies have delved into the synthesis of spinels containing more than four metal cations, for which conventional syntheses from pure chemical precursors are costly and generate significant waste. Here we demonstrate a facile, rapid and scalable synthesis of layered spinel ferrite catalysts from fly ash waste that is otherwise detrimental to landfill ecosystems. The optimum waste-derived catalyst primarily comprised MgAl0.2Fe1.8O4, with a distorted structure due to the substitution of various cations (Ca2+, Mn2+, Mn3+, and Ti4+) at tetrahedral and/or octahedral iron sites, and demonstrates high activity (1.26 mmol⋅g−1⋅min−1) and stability (>100 h) for acetic acid ketonisation at a modest temperature (300 °C). Acidity measurements yield a corresponding turnover frequency of 2.21 min−1. Strong synergies are observed between the different metallic cations and octahedral Fe2+ species; XANES and in-situ DRIFTS indicate the latter is the primary active sites for ketonisation in fly ash-derived spinel ferrites, promoting both acetic acid adsorption as bidentate acetate and subsequent C–C coupling to acetone.

Recent Developments on Aluminum 7075-Based Composite with Industrial Waste Fly Ash by Stir Casting and Their Applications

Recent Developments on Aluminum 7075-Based Composite with Industrial Waste Fly Ash by Stir Casting and Their Applications

САМОУПРОЧНЕННЫЕ ГИПСОВЫЕ КОМПОЗИЦИИ НА ОСНОВЕ ЗОЛ-УНОСА

This work is devoted to the study of self-reinforced gypsum stone with increased strength properties and low creep due to the reinforcement of the gypsum matrix with filiform ettringite crystals. However, with this method of self-reinforcement, difficulties may arise in providing a sufficient volume of an alkaline medium when using a saturated solution of calcium hydroxide obtained by slaking air calcium lime. The method is simplified by replacing saturated lime solutions with powder mixtures of fly ash captured by electrostatic precipitator systems during combustion of coals from the Kansk-Achinsk brown coal basin at thermal power plants. Gypsum composite based on fly ash has increased strength, which confirms the possibility of effective use of fly ash from the combustion of brown coal in building gypsum composites used to create structural elements of buildings. According to the study of the results of microscopic imaging of the resulting self-reinforced structure, the forming gypsum matrix becomes denser with differently directed crystals and fly ash microspheres included in the work. Utilization of fly ash waste in the composition of reinforced composites allows not only to simplify the method of self-reinforcement, reduce costs, but also to solve the problem of recycling chemically active ash.

Rheology, shrinkage, mechanical properties and microstructure of ultra-light-weight concrete with fly ash cenospheres

Cenospheres are low-density and hollow microspheres derived from coal-fired power plant fly ash waste. This study aims to prepare ultra-light-weight (<1000 kg/m3 wet density) concrete using fly ash cenospheres (FAC). To begin with, FAC's shell thickness and the water absorption and desorption were characterized. A mixing procedure was designed to avoid the segregation between the FAC and cement slurry. FAC can affect the rheological properties of fresh mixture over time through absorption and desorption of free water. The presented ultra-light-weight concrete has several advantages compared to the ones prepared using foaming methods. First, shrinkage is significantly reduced due to FAC's internal restraint and curing effects. Secondly, it has good mechanical performance, especially in bending and is more environmentally friendly due to use of less cement. X-ray computed tomography illustrates that FAC ultra-light-weight concrete has smaller pores of more uniform size compared with those prepared using foaming methods. X-Ray diffraction, thermal gravimetry-derivative thermal gravimetry, fourier-transform infrared spectroscopy and scanning electron microscopy are employed for the hydration products and microstructure characterization. Outcomes prove that FAC can combine well with the cement matrix, and react with calcium hydroxide to produce C-A-S-H through pozzolanic reaction.