Waste Fly Ash Research Articles

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

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.

Zirconosilicate Sorbent Based on Waste Fly Ash Cenospheres for Cesium Immobilization in a Ceramic Form

Zirconosilicate Sorbent Based on Waste Fly Ash Cenospheres for Cesium Immobilization in a Ceramic Form

Advancements in Lightweight Artificial Aggregates: Typologies, Compositions, Applications, and Prospects for the Future

Currently, the environment and its natural resources face many issues related to the depletion of natural resources, in addition to the increase in environmental pollution resulting from uncontrolled waste disposal. Therefore, it is crucial to identify practical and effective ways to utilize these wastes, such as transforming them into environmentally friendly concrete. Artificial lightweight aggregates (ALWAs) are gaining interest because of their shift in focus from natural aggregates. Researchers have developed numerous ALWAs to eliminate the need for natural aggregates. This article explores the diverse applications of ALWAs across different industries. ALWAs are currently in the research phase due to various limitations compared to the availability of the various natural aggregates that form more durable solutions. However, researchers have discovered that certain artificial aggregates prioritize weight over strength, allowing for the effective use of ALWAs in applications like pavements. We thoroughly studied the various ALWAs discussed in this article and found that fly ash and construction waste are the most diverse sources of primary material for ALWAs. However, the production of these aggregates also presents challenges in terms of processing and optimization. This article’s case study reveals that ALWAs, consisting of 80% fly ash, 5% blast-furnace slag, and only 15% cement, can yield a sustainable solution. In the single- and double-step palletization, the aggregate proved to be less environmentally harmful. Additionally, the production of ALWAs has a reduced carbon footprint due to the recycling of various waste materials, including aggregates derived from fly ash, marble sludge, and ground granulated blast-furnace slag. Despite their limited mechanical strength, the aggregates exhibit superior performance, making them suitable for use in high-rise buildings and landscapes. Researchers have found that composition plays a key role in determining the application-based properties of aggregates. This article also discusses environmental and sustainability considerations, as well as future trends in the LWA field. Simultaneously, recycling ALWAs can reduce waste and promote sustainable construction. However, this article discusses and researches the challenges associated with the production and processing of ALWAs.

Analysis Of Flexural Resistance And Environmental Feasibility Of Ferrocement Concrete Slabs From Fly Ash And Sandblasting Waste

Sandblasting waste from the shipbuilding industry and fly ash waste from industry and electric steam power plants in Indonesia are relatively high in quantity, are B3, and can potentially cause serious environmental pollution. This research aims to utilize this waste as material for ferrocement concrete, where the SiO2 and Al2O3 content from fly ash replaces some of the cement, silica sand from sandblasting waste replaces sand, and additional wire mesh as reinforcement. The method used is a quantitative experiment, where the material to be used is tested for gradation and TCLP. The finished ferrocement concrete is tested for flexural strength. The test results show that the raw material meets the gradation standards in SNI 03 2834 2000, as well the TCLP test results which show that the B3 heavy metal content is Barium, Zinc, and Copper in the sandblasting waste value is below the quality standards of PP No. 22 of 2021 Appendix XI so that all materials can be used for mix designs. The mix design created has a composition ratio of 1S:1.5PB, 1S:1.5PB:50AT, 1S:2PB, and 1S:1PB:50AT. The 1S:2PB ratio composition has the highest average flexural strength, namely 17.46 MPa, which is suitable for light vertical load construction work

The Use of Waste Materials Red Mud and Fly Ash as Road Embankment Fill

This study provides a comprehensive evaluation of red mud as a sustainable material for road base construction, particularly in combination with bottom ash. Red mud, a by-product of the Bayer process used in alumina extraction, is known for its high alkalinity and heavy metal content. For this reason, this waste material causes environmental challenges. Red mud sourced from the Eti Aluminum Factory in Seydişehir, Konya (Turkey), was stabilized with bottom ash. Then, these waste materials were tested through a number of experiments, such as in relation to their Atterberg limits, compaction characteristics, unconfined compressive strength (UCS), California bearing ratio (CBR), and microstructure through a scanning electron microscopy (SEM) analysis. The results highlight that the UCS of stabilized red mud samples significantly improved with the addition of bottom ash and longer curing periods. Specifically, the UCS values increased from 0.5 MPa to 2.5 MPa after 28 days of curing. Moreover, RM specimens stabilized with 25% bottom ash achieved a CBR value of 146.64% after 28 days, far exceeding Turkey’s road fill material requirement, which mandates a minimum unsoaked CBR value of 15%. These findings indicate that red mud stabilized with bottom ash not only meets but exceeds the structural requirements for road base materials. This approach provides a sustainable solution for the environmental management of red mud while contributing to infrastructure development. Through the recycling of these industrial by-products, this study presents a viable method to reduce waste and support economic and environmental sustainability in road construction projects.

Solid‐phase synthesis of silicalite‐1 molecular sieve based on fly ash and its CO2 adsorption performance

AbstractIn this work, an alkali melting‐pickling assisted solid phase synthesis method of S‐1 zeolite molecular sieve with excellent adsorption properties for CO2 was successfully developed by using solid waste fly ash. SiO2 with a purity of up to 97.84% was successfully extracted by using alkaline fusion activation, high temperature calcination and pickling. The CO2 adsorption capacity of the prepared SiO2 was 0.51 mmol/g at 298 K and 1 bar. Silicalite‐1 molecular sieve was prepared by solid phase synthesis method using SiO2 extracted from fly ash as silicon source. The results showed that the prepared Silicalite‐1 had good morphology and relatively high crystallinity. The specific surface area is 623.30 m2/g, and the total pore volume is 0.31 cm3/g. In addition, the adsorption capacity of CO2 was 2.05 mmol/g at 298 K and 1 bar. Compared with the prepared SiO2, the adsorption capacity of CO2 by Silicalite‐1 molecular sieve increased by four times. Moreover, under the test condition of 298 K, it has a high selectivity coefficient for CO2/N2 mixed gas, and after 10 times of adsorption‐desorption cycle tests, the adsorption capacity of Silicalite‐1 molecular sieve for CO2 does not change significantly, and its adsorption rate can still be as high as 89.31%. The results indicate that Silicalite‐1 molecular sieve prepared by solid phase synthesis method has good adsorption selectivity and adsorption–desorption cycle regeneration stability, and can be used in the field of CO2 adsorption, separation and purification. © 2024 Society of Chemical Industry and John Wiley &amp; Sons, Ltd.

Evaluation on Preparation and Performance of a Low-Carbon Alkali-Activated Recycled Concrete under Different Cementitious Material Systems.

A green, low-carbon concrete is a top way to recycle waste in construction. This study uses industrial solid waste slag powder (S95) and fly ash (FA) as binders to completely replace cement. This study used recycled coarse aggregate (RCA) instead of natural coarse aggregate (NCA). This is to prepare alkali-activated recycled concrete (AARC) with different cementitious material systems. Alkali-activated concrete (AAC) mixtures are modified for strength and performance based on the mechanical qualities and durability of AARC. Also, the time-varying effects of the environment on AARC properties are explored. The results show that with the performance enhancement of RCA, the mechanical performance of AARC is significantly improved. As RCA's quality improves, so does AARC's compressive strength. At a cementitious material content of 550 kg/m3, AARC's 28d compressive strengths using I-, II-, and III-class RCA were reduced by 2.2%, 12.7%, and 21.8%, respectively. I-class AARC has characteristics similar to natural aggregate concrete (NAC) in terms of shrinkage, resistance to chloride penetration, carbonization, and frost resistance. AARC is a new type of green building material that uses industrial solid waste to prepare alkali-activated cementitious materials. It can effectively reduce the amount of cement and alleviate energy consumption. This is conducive to the reuse of resources, environmental protection, and sustainable development.

Mechanical property and microstructure of fly ash-based geopolymer by calcium activators

Geopolymer is a green and environmentally friendly new type of gel material generated from the reaction of activators with silica-alumina raw materials, possessing extensive research and application value. Fly ash can be used as reaction material, enabling the industrial solid waste to be recycled and reused. In this paper, unconfined compressive strength test, X-ray diffraction analysis, Fourier transform infrared light, 29Si nuclear magnetic resonance, scanning electron microscope and energy disperse spectroscopy, and physisorption experiment were carried out to study the effects of the type and dosage on the mechanical property and microstructure of fly ash-based geopolymer activated by calcium hydroxide, calcium sulfate and their compound. The results indicated that calcium hydroxide and calcium sulfate can promote the dissolution of fly ash crystals, providing adequate Ca2+ for the formation of gel products. The products of calcium hydroxide and calcium sulfate activation are hydrated calcium aluminate, hydrated calcium sulfate, and ettringite, respectively. The effect of the compound activator is superior to that of single activators. With the increase of the proportion of calcium hydroxide, the reorganization and polymerization of gel products were accelerated so that the integrity and continuity of the microstructure of geopolymer were improved, and then the strength increased. When the ratio of calcium hydroxide to calcium sulfate was 3:1 and the total dosage was 20 %, the unconfined compressive strength reached the maximum value. According to this study, it was investigated that type and dosage of calcium activators had evident influence on the geopolymerization of fly ash. And the reutilization and resource utilization of fly ash waste can be achieved, which can provide an engineering theoretical basis for using fly ash-based geopolymer to alter the physical and chemical properties of special soils and achieve solidification effect.

Nanosilica-enhanced geopolymer cementitious materials: Mechanistic insights from experimental and computational simulations

To mitigate the pollution associated with municipal solid waste incineration fly ash (MSW-IFA), solidification/stabilization (S/S) techniques have garnered considerable attention. This study systematically investigates the modification effects of nanosilica (NS) on the properties of geopolymer functional cementitious materials (GFCM) derived from waste fly ash. By integrating experimental data with simulation-based calculations, the influence of NS on the macroscopic properties and microstructure of GFCM, including mechanical performance, heavy metal immobilization mechanisms, and hydration processes, was examined. The results indicate that NS enhances mineral phase and pore structure through pozzolanic and filling effects, promoting additional C-S-H gel formation and pore filling, which significantly accelerates the hydration process and improves mechanical properties. Furthermore, NS increases the proportion of heavy metals in a stable state, thereby reducing their leaching potential. Density functional theory (DFT) calculations further revealed that NS's modification effects primarily occur via filling, nucleation, and pozzolanic activity, which supported the construction of a geopolymer reaction network. This study offers a validated approach for advancing the understanding of NS modification mechanisms, the development of geopolymer reaction networks, and the mechanisms governing heavy metal S/S.

Smart Green Concrete: Innovation of Concrete Materials from Fly ash Waste and Lapindo Mud Integrated Smart E. crassipes Coir Geotextile to Realize Indonesia's Sustainable Infrastructure

Pariaman City, situated near the Semangko fault and the Indo-Australian plate subduction zone, is highly prone to earthquakes and tsunamis. To address this, the Earthquake Buddy Application (EDY App) was developed as an innovative solution for disaster mitigation. EDY App utilizes Geographic Information Systems (GIS) to provide real-time earthquake vulnerability maps, early warnings, and evacuation route suggestions to Temporary Evacuation Sites (TES). It also offers education on earthquake preparedness and facilitates donations for relief efforts. The application’s main contribution lies in its integration of comprehensive disaster management tools into one platform. By providing critical information during emergencies, the app empowers users to make informed decisions, which can reduce casualties in high-risk areas. The app also encourages community preparedness by offering accessible education on earthquake mitigation. EDY App is designed to create a disaster-resilient society in Pariaman, ensuring that residents are better equipped to respond to natural disasters through real-time alerts and evacuation support, ultimately enhancing local preparedness and reducing the potential impact of future earthquakes.

Novel high-efficiency solid particle foam stabilizer: Effects of modified fly ash on foam properties and foam concrete

The preparation of foam concrete frequently encounters challenges such as foam collapse and stratification, which lead to a decline in material performance. Therefore, enhancing foam stability is paramount in the production of foam concrete. This study innovatively addresses this issue by investigating the use of waste fly ash particles (RFA) and modified fly ash (AMFA, BMFA, and CMFA) as foam stabilizers, and comparing their efficacy with that of traditional nano-silica stabilizers (NS), both independently and in combination. The results indicate that modified ultrafine fly ash particles (AMFA) exhibit foam stability properties (1-h settlement distance and bleeding rate) comparable to those of NS. Moreover, when combined with NS, the mixture surpasses the foam performance of NS alone. Utilizing these highly stable foams, lightweight foam concrete with a 600 kg/m³ density is produced, demonstrating exceptional mechanical properties (compressive strength of 3.42 MPa) and superior thermal insulation (thermal conductivity of 0.0914 W/m· K). The enhanced foam stability of the modified fly ash is primarily attributed to increased surface roughness, hydrogen bonding, and van der Waals forces. Developing highly stable foams holds significant potential, contributing to energy conservation, emissions reduction, and waste management.

Fly-ash derived crystalline Si (cSi) Improves the capacity and energy density of LiNi0.8Co0.1Mn0.1O2 battery: Synthesis and performance

For decades, graphite has been the key ingredient in the anode of Li-ion batteries (LIBs). The search for high-capacity anode materials for Li-ion batteries (LIBs) has led to increasing interest in silicon (Si) as a potential replacement for graphite. This study presents an innovative approach to synthesizing crystalline Si (cSi) from type C fly ash, addressing both the need for improved LIB anodes and the challenge of industrial waste management. Our novel process involves a stepwise method of extraction, gelation using various mineral acids (HCl, H2SO4, and HNO3), magnesiothermic reduction, and purification. X-ray diffraction and energy-dispersive X-ray spectroscopy confirmed the production of high-purity SiO2 and cSi. Notably, a cSi-doped graphite anode (5 % Si) paired with LiNi0.8Mn0.1Co0.1O2 (NMC811) in a cylindrical cell achieved a minimum specific discharge capacity of 388 mAh/ganode after formation, surpassing the theoretical capacity of graphite (372 mAh/g). This demonstrates that even a small amount of cSi can significantly enhance anode performance. Our scalable, simple, and economical process offers a dual benefit: improving battery characteristics while providing an efficient method for fly ash waste utilization. This approach paves the way for sustainable production of high-performance LIB anodes while addressing critical waste management challenges.

Effect of fly ash and ground waste glass as cement replacement in concrete 3D-Printing for sustainable construction

Effect of fly ash and ground waste glass as cement replacement in concrete 3D-Printing for sustainable construction

A Study on the Mechanisms of Coal Fly Ash to Improve the CO2 Capture Efficiency of Calcium-Based Adsorbents

Utilizing calcium-based adsorbents for CO2 adsorption through cyclic calcination/carbonization is one of the most cost-effective methods for carbon emission reduction. In order to improve the cycle stability of the adsorbents and the capture efficiency of CO2, this study used industrial solid waste coal fly ash for the hydration treatment of calcium-based adsorbent to explore the variations in the cyclic adsorption performance of the adsorbent under different doping ratios and hydration conditions. By means of various characterization techniques, the microscopic mechanism for improving the performance of the modified adsorbent was analyzed from the perspectives of chemical composition, physical structure, and surface functional groups of the adsorbents. The results demonstrated that the modification of coal fly ash could significantly enhance the carbonation performance and cycle stability of the adsorbent in multiple CO2 capture processes. The modified material doped with 5% coal fly ash had the highest total CO2 adsorption capacity, which increased by 13.7% compared to before modification. Additionally, the modified material doped with 10% coal fly ash exhibited the strongest cyclic adsorption capacity, which was 14.0% higher than that before modification, and the adsorption attenuation rate decreased by 32.2%. The characterization results showed that the reaction between calcium oxide and coal fly ash formed CaSiO3 and Ca12Al14O33 during the modification process, which was the primary reason for the improvement in the CO2 capture performance of the modified materials. This study provided a new perspective on the resource utilization of solid waste fly ash and efficient CO2 capture.

Life cycle assessment of ceramic tiles manufactured using industrial waste fly ash

Sustainability in the ceramic tile industry is critical due to its significant resource and energy consumption. With limited life cycle assessment (LCA) studies on waste materials in tile production, a research gap exists specifically for industrial waste fly ash (IWA). Building upon previous research that has confirmed the technical feasibility of IWA as a sustainable alternative material in ceramic tile, this study explores the environmental and economic feasibility of replacing potash feldspar with IWA in ceramic tiles. A comparative LCA across scenarios with varying IWA additions from 0 % to 30 % was conducted, focusing on six key environmental impact categories: climate change, terrestrial acidification, human toxicity, terrestrial ecotoxicity, freshwater eutrophication, and fossil depletion. Additionally, a sensitivity analysis on increased production energy and an environmental life cycle cost analysis (ELCC) were performed. Results reveal significant reductions in environmental impacts with increased IWA incorporation compared to the conventional construction. Notably, the IWA30 (30 % IWA addition) scenario, which entirely substitutes potash feldspar, achieves the most substantial benefits, reducing climate change impacts by 8 %, terrestrial acidification by 10 %, and terrestrial ecotoxicity by 22 %. These reductions demonstrate that incorporating IWA significantly decreases the overall environmental footprint of ceramic tile production by reducing the reliance on non-renewable resources and mitigating pollution. IWA30 also proves to be the most cost-effective option, with an 11 % cost reduction due to IWA's availability as a waste material. Overall, adopting IWA decreases the environmental burden and enhances economic viability, providing strong incentives for industries to adopt more sustainable practices by minimising waste management challenges and raw material consumption.

Possibility of Making Plastic Roof Tiles from Waste Plastic, Sand, and Fly Ash

Possibility of Making Plastic Roof Tiles from Waste Plastic, Sand, and Fly Ash

Synthesization and characterizations of coal fly ash-coffee grounds-based composite as super-absorbent for application in soil

To recycle and utilize two types of harmful solid waste, coffee grounds (CG) and coal fly ash (CFA), a novel and low-cost superabsorbent composite (MCG-PAA/CFA) was synthesized by aqueous solution polymerization with modified coffee grounds (MCG), acrylic acid (AA) and CFA as raw materials, and it was applied to soil to improve its drought resistance. Various reaction conditions were comprehensively investigated and analyzed to assess their influence on the water absorbency of the superabsorbent composite (SAC). After optimization, the MCG-PAA/CFA exhibited water absorbency capacities of 1260(±10.6) g/g and 82(±1.4) g/g in deionized water and physiological saline, respectively. After adding 3 wt% MCG, the water absorption of SAC was improved from 415 to 746 g/g. After further introduction of 2 wt% CFA, the water absorption of SAC increased from 746 to 1260 g/g. Fourier Transform Infrared (FTIR) analysis confirmed that the grafting reaction was successful and that CFA participated in the reaction, while scanning electron microscope (SEM) and thermogravimetric analysis (TGA) results revealed that the grafting reaction and the introduction of CFA improved the surface morphology and thermal stability of the SAC. Kinetic analysis was conducted to investigate how the grafting reaction and the introduction of CFA affected the swelling and water retention kinetics of the superabsorbent composite. In the soil experiment, adding only 0.1 wt% MCG-PAA/CFA can improve the water holding capacity of sandy soil, loam soil and clay soil by 6.65%, 4.42%, and 3.76% respectively This SAC composite has great potential in soil drought resistance.

Performance and microstructural characterization of fiber-reinforced cement-based grout incorporating waste tailing sand and fly ash

A fiber-reinforced cement and tailing sand-based grout (FRCTG) was proposed to improve the utilization of solid waste in construction. Different grout specimens were prepared using various proportions of ordinary Portland cement, iron tailing sand (ITS), fly ash (FA), basalt fibers (BFs), and water as raw materials. Used single-factor test, orthogonal test and artificial neural network model that provided a comparative analysis of the change in the rheological and mechanical properties of different grout mixes according to their component ratios. Furthermore, microscopic characterization techniques were used to reveal the intrinsic physicochemical mechanisms underlying the structural evolution of the considered grouting materials. The results indicate that ITS significantly increases the rheological properties of the grouting material. The maximum strength of the grouting material is achieved when the length of BF is 6 mm and the dosage is 0.2 %. An 8 % dosage of FA can effectively improve the rheological properties of the grouting material and enhance its flexural strength. Microscopic tests reveal that SiO2 in ITS exists in the form of quartz with low reactivity, thereby inhibiting the hydration reaction of the binder material. Different distribution patterns allow BF to serve both as reinforcement for the matrix and as a framework for hydration products, effectively enhancing the density between the BF and the surrounding matrix. The surface of FA is covered in layers by hydration products, forming a chain-like structure that improves bonding strength with the material. The results of this research offer a high-performance, low-cost, and environmentally friendly grouting material for construction grouting projects, which is of significant importance for promoting innovation in comprehensive utilization of solid waste.

Sintesis dan Karakterisasi Zeolit X dari Fly Ash Batu Bara Menggunakan Metode Sintesis pada Suhu Rendah

Many industries in Indonesia have switched to using coal fuel. The use of coal at PT PLTU Paiton has reached 250 tons per hour and produces 4% of waste by-products of combustion contained from bottom ash by 25% and fly ash by 75%. Fly ash waste will harm the environment and health. Fly ash contains many components, including SiO2 52%, Al2O3 31.86%, Fe2O2 4.89%, CaO 2.68%, and MgO 4.66%. This research aims to synthesize and characterize zeolite X from PT Paiton fly ash using a low-temperature synthesis method. Zeolite X synthesis in this study has 3 steps: The pretreatment process, silica synthesis process, and zeolite synthesis process. The results of silica synthesis obtained SiO2 55.54%. The resulting zeolite product has a typical peak at 2ϴ 28.72. Zeolite x has a wavelength of 430, 570, 695,7, and 965,7, which respectively indicates Si-O-Si and Si-O-Al bonds, double ring bonds, T-O ring symmetric strain (internal), and asymmetric (internal). The results of zeolite X crystal synthesis in this study could not be formed in the variable of adding time of 3-5 hours with a variation of moles of Al2O3 0,5-1,5 moles.