Properties Of Fly Ash Research Articles

Influence of Nano-Fly Ash on mechanical properties, microstructure characteristics and sustainability analysis of Alkali Activated Concrete

Ordinary Portland Cement (OPC) composites significantly affect the atmosphere by emitting Carbon dioxide (CO2) during its production process. The addition of Nano Materials (NM) for the construction could change the matrix configuration at the nano level. Compared to other NMs, converting industrial by-products and locally available materials into nano size can enhance the characteristics of the binder composites. This research work focuses on the effects of Nano Fly ash (nFA), on the fresh, mechanical, microstructural, and thermal resistance properties of Fly Ash (FA) and Ground Granulated Blast Furnace Slag (GGBFS) based Alkaline Activator Nano Concrete (AANC). The impact of adding nFA in various concentrations of 3 %, 6 %, 9 %, 12 %, and 15 % on the properties of AANC was studied. By adding nFA in an optimal proportion, the degree of geo-polymerization is improved which is found by Field Emission Scanning Electron Microscopy (FESEM), X-ray diffraction (XRD), Thermogravimetric analysis (TGA), Energy Dispersive X-Ray Analysis (EDAX) and Fourier Transform Infrared (FTIR). Results indicate that the addition of nFA significantly increased polymerization, reducing initial and final setting times by 13.3 %–52.5 % and 5.3 %–28.8 %, respectively. Moreover, nFA promoted the formation of polymer gel, leading to a denser microstructure with fewer cracks and refined pores, resulting in a substantial increase in mechanical strength, particularly with 9% nFA, achieving an optimal CS of 56.14 MPa after 28 days which is 37.97 % improvement compared to the mix without nFA. However, when nFA was added, beyond 9 %, the performances declined due to its high surface area resulting in a non-uniform dispersion that promoted agglomeration. This dispersion enhances the formation of C-A-S-H and C–S–H gels. The addition of nFA in AANC can be an environmentally friendly solution by reducing CO2 emissions, energy consumption, cost reduction and increased sustainability.

Durability, Capillary Rise and Water Absorption Properties of a Fiber-Reinforced Cement-Stabilized Fly Ash–Stone Dust Mixture

The management of unutilized fly ash poses challenges due to concerns about storage and its potential groundwater contamination. Within the road industry, where the bulk utilization of fly ash is feasible, its unsuitability for use in the base and sub-base layers of pavements due to its low strength and a high proportion of fine particles has been a limitation. The incorporation of stone dust alongside fly ash, treated with lime or cement, yields superior strength and stiffness. Apart from strength, the stabilized mix’s durability, capillary rise, and water absorption properties are crucial for determining its suitability for pavement applications. Observations from this study reveal that fiber-reinforced cement-stabilized fly ash–stone aggregate specimens treated with 4% and 6% cement, with and without fibers, met the limiting mass loss of 20%, as specified in IRC SP: 89. The mass loss decreases with an increase in cement and fiber content. However, the capillary rise in the mixes increases with a higher percentage of fly ash and fiber content but decreases with increased cement content. Cement addition results in a reduction in water absorption; however, the addition of fibers results in an increase in water absorption. A linear correlation has been established between mass loss and UCS and IDT, which can be used to evaluate the suitability of materials for the structural layer without conducting a wet–dry durability test, which typically takes one month. This study proposes that cement-stabilized fly ash and stone aggregate mixtures with 4% and 6% cement can be used as the subbase and base of pavement based on wet–dry mass loss criteria and water absorption criteria. Observations from this study reveal that fiber-reinforced cement-stabilized fly ash–stone aggregate specimens treated with 4% and 6% cement, with and without fibers, met the limiting mass loss of 20%, as specified in IRC SP: 89. The mass loss decreases with an increase in cement and fiber content. However, the capillary rise in the mixes increases with a higher percentage of fly ash and fiber content but decreases with increased cement content. Cement addition results in reduction in water absorption. However, the addition of fibers results in increase in water absorption. A linear correlation is established between mass loss and UCS and IDT, which can be used to evaluate the suitability of materials for the structural layer without conducting wet–dry durability tests, which take one month. This study proposes that cement-stabilized fly ash and stone aggregate mixtures with 4% and 6% cement can be used as the subbase and base of pavement based on wet–dry mass loss criteria and water absorption criteria.

Study on the characterization of fly ash and physicochemical properties of soil, water for the potential sustainable agriculture use – A farmer's perspectives

AbstractIn this study, suitable fly ash (FA) was selected for agricultural purposes according to combined characteristic soils and water. The two FAs from the Tuticorin Thermal Power Plant (FA-TTPP) and Sripathy Thermal Power Station (FA-STPS) and physio-chemical analysis of soil and water samples from the five different sites (1–5) in Viruthunagar district, Tamilnadu is made. X-ray diffraction analysis (XRD) of FAs showed that quartz (SiO2), mullite (Al6Si2O), and hematite (Fe2O3) are available that enhance plant growth. The Fourier-transform infrared spectroscopy (FTIR) results confirmed that Si–O–Si, Al–O–Si, HO–OH, and OH bonding present in the FAs support to meet the required plant nutrients in the soil. Scanning electron microscopy analysis (SEM) of FA-TTPP revealed compact microspheres with regular, smooth, and irregular textures while FA-STPS showed glassy, unshaped fragments that may help to improve the texture of field sites. Energy dispersive X-ray spectroscopy (EDX) analysis found that FAs have essential macro- and micronutrients to minimize the soil nutrient and thus help to improve plant productivity. Sites 1 and 2 have acidic soil conditions and are recommended to use both FAs since they are alkaline in nature. FA can improve the water-holding capacity of sandy loam soils of sites 2, 3, and 4 due to the presence of fineness content in FA. Site- 1 has iron deficiency which can be remediated with rich iron FA-STPS. It is recommended to use optimum FA based on soil and water to improve agricultural efficiency.

Novel Understandings of Biomineralization in Backfill Materials: A Fundamental Investigation of Coal Gangue and Fly Ash Impact on B. pasteurii to Enhance Material Properties

This paper proposes a fundamental investigation of coal gangue and fly ash impact on B. pasteurii to enhance the properties of backfill materials. The goal is to obtain effective microbial mineralization and potential mechanical properties of coal gangue and fly ash as backfill materials and to mitigate the impact of the most common binders used in the backfill material of mines. Micro-scale mineralization was performed with B. pasteurii bacteria using microbially induced carbonate precipitation (MICP) technology to clarify solid waste impact on B. pasteurii and to bind coal gangue and fly ash. Several tests were carried out to analyze the behavior of B. pasteurii, especially when it coexists with these two waste materials separately. In such cases, it was possible to observe a reduction in mineralization initiation time with respect to the natural mineralization of the MICP technology. Moreover, at the macro-scale, the new mineralized backfilling material shows good workability in the fresh state, whereas the strength at 28 days is 5.34 times higher than that obtained with non-mineralized coal gangue and fly ash.

Assessment of enhanced strength and stiffness properties of bio-engineered coal fly ash

This study investigates the use of urease-producing bacteria for microbial induced calcite precipitation (MICP) to enhance the mechanical properties of coal fly ash (CFA). Sporosarcina pasteurii was employed to treat CFA with cementation solutions over 7, 14, and 28 days. Biotreated samples exhibited improved compressive strength, shear strength, stiffness, and cohesion. Calcite precipitation increased, and permeability decreased with treatment cycles, resulting in a 78% reduction in permeability and 8% calcite precipitation in a 28-day cycle. X-ray diffraction (XRD) and scanning electron microscope (SEM) investigations support the improved engineering properties of bioengineered coal fly ash (BCFA) samples.

Synergistic effect of graphene oxide and coloidalnano-silica on the microstructure and strength properties of fly ash blended cement composites

Synergistic effect of graphene oxide and coloidalnano-silica on the microstructure and strength properties of fly ash blended cement composites

Durability Properties of High-Strength Concrete Containing Fly Ash, Dolomite Powder and Slag Sand

Concrete is the most extensively utilized construction material worldwide. The production and demand for cement have seen significant growth, but this increased demand has raised concerns about its environmental impact within the construction industry. Concrete can be produced using alternative materials or substitutions for cement, fine aggregate and coarse aggregate, often utilizing waste materials. In this study, dolomite powder and fly ash used as a partial replacement for cement and slag sand is used as a 100% replacement to natural sand. Dolomite powder shares certain properties with cement, making it a cost-effective alternative that can enhance the strength of concrete. The disposal of fly ash is becoming a significant environmental concern due to its potential environmental hazards as a waste material. Using fly ash is not only cost-effective but also improves the workability, strength, and durability of concrete. Additionally, the use of slag sand not only contributes to environmental conservation but also enhances the structural strength and durability of concrete. The reason is the high tensile strength of slag. The durability tests on this project are water absorption, acid and alkali resistance tests. In these tests, an acid resistance test involves the use of 5% dilute sulfuric acid (H2SO4) by volume of water, while an alkali resistance test uses 5% sodium hydroxide (NaOH) by weight of water. These tests are conducted using M60 grade concrete mixtures, which incorporate partial replacements of cement with fly ash ranging from 0% to 10% by weight of cement, and dolomite ranging from 0% to 20% by weight of cement. Additionally, fine aggregate is replaced with slag sand in these mixtures.

Exploring elastic properties of fly ash recycled aggregate concrete: Insights from multiscale modeling and machine learning

The primary focus of this study is to analyze the impact of different components of fly ash recycled aggregate concrete (FARAC) on its elastic properties, aiming to suggest it as a potential alternative to traditional concrete. For this study, a variety of techniques were employed, such as multiscale modeling, finite element methods, and Mori-Tanaka theory. The study employed supervised machine learning methods to conduct classification and regression analyses, with the goal of investigating the impact of mix proportion on elastic properties. The results obtained from the machine learning models suggest that the XGBoost and K-Nearest Neighbors algorithms have shown exceptional precision when compared to the other algorithms, achieving an accuracy of over 0.9. The current investigation reveals that the elastic characteristics of FARAC are primarily affected by fly ash and calcium silicate hydrate (C-S-H) in comparison to other components. According to the research findings, incorporating recycled aggregate content in the range of 0–100% resulted in a 25% decrease in Young's modulus and an 8% increase in Poisson's ratio of FARAC. In addition, two web-based applications have been developed to calculate the elastic properties of composite materials with spherical inclusions using the Mori-Tanaka theory, and to predict the elastic properties of FARAC through machine learning.

Mechanical properties of fly ash and silica fume based geopolymer concrete made with magnetized water activator

Using of magnetized water (MW) in the manufacturing of Portland cement concrete has shown promising effects in recent decades. This research investigates the effect of using alkaline activator (AA) solution prepared with MW on producing fly ash (FA) and silica fume (SF) based geopolymer concrete. The MW was prepared by passing tap water (TW) through two permanent magnetic fields of 1.4 and 1.6 Tesla intensities. Sodium hydroxide (SH), potassium hydroxide (PH), and sodium silicate (SS) solutions were the AA used. In total, 28 geopolymer concrete mixes were produced and tested in this study. Half of the mixes was made with the proposed MW (activator and added water), and compared with the other half that made with TW (activator and added water). Variables like; water type (TW or MW), SF content (10%−100%), AA type (SH+SS or PH+SS), AA concentration, AA to cementitious materials (AA/C) ratio, and water to cementitious materials (W/C) ratio were applied in this study. Physical and chemical properties of the utilized water and AA were measured. Concrete fresh and hardened mechanical properties were measured including workability, compressive strength, tensile strength, flexural strength, bond strength, and water absorption. Ultrasonic pulse velocity non-destructive testing was also conducted on the produced concrete. Scanning electronic microscope (SEM), energy dispersive X-ray (EDX), and X-ray diffraction (XRD) analyses were carried out on selected mixes to closely investigate the microstructure of the introduced geopolymer concrete. The results showed that compared with TW, utilizing MW in preparing the AA of geopolymer concrete caused notable increase in the concrete slump with an average of 14%, compressive strength increase by up to 64%, tensile strength increase by up to 60%, flexural strength increase by up to 41%, bond strength increase by up to 40%, and water absorption decrease by up to 38%.

Investigations on Strength and Durability Properties of Recycle Aggregate and Fly Ash in Concrete

In this investigative study the Natural Coarse Aggregate (NCA) were put back with Recycled Course Aggregate (RCA) at peculiar proportions, the mechanical performance and durability properties of concrete are examined. The inclusion of fly ash (FA) is also introduced as stand–in of Cement. The present investigation aims to determine the effect of RCA as an stand-in material to NCA and to analyze the fresh properties like workability, density and hardened properties like Compressive Strength, Flexure Strength, Split Tensile Strength and durability properties like Water permeability and Sorptivity. Mix is formulated for water cement ratio 0.40. The specimens were casted of replacing virgin aggregate with RCA by 10% and 20%, and cement with FA by 10%, 20% and 30%. All the specimens are cured for 7 and 28 days as per requirement later they are tested. The acquired data are then compared between the strength of NCA of concrete and the proportion of RCA and FA. The outcome view is in such a way that the workability of concrete will decline as the replacement of RCA increases, by which it should limited to a fixed percentage (10% or 20%). The density of concrete is not altered by the put back of FA, but raise in percentage of RCA replacement could alter the density of concrete. In case of Compressive, Flexure and Split tensile strength of concrete the optimum strength obtained for 10% FA and 10% RCA for 7 and 28 days was similar to that of 100% NCA and 0% FA and durability studies also gave the optimum results for the same replacement.

Properties of fly ash from thermal treatment of municipal sewage sludge in terms of EN 450-1

Properties of fly ash from thermal treatment of municipal sewage sludge in terms of EN 450-1

Effect of Curing Age on Tensile Properties of Fly Ash Based Engineered Geopolymer Composites (FA-EGC) by Uniaxial Tensile Test and Ultrasonic Pulse Velocity Method

Effect of Curing Age on Tensile Properties of Fly Ash Based Engineered Geopolymer Composites (FA-EGC) by Uniaxial Tensile Test and Ultrasonic Pulse Velocity Method

Mechanical and durability properties of structural grade heavy weight concrete with fly ash and slag

The paper investigates the fundamental mechanical and durability properties of a M50 strength grade heavy weight concrete (HWC), with replacement of cement by fly ash at 15 %, 25 % and 35 % levels and slag at 40 %, 50 % and 60 % levels. The mechanical properties studied include compressive strength, elastic modulus, flexural and split tensile strengths, and the durability properties include water permeability, drying shrinkage and carbonation behavior. Although extended curing improves mechanical strength and water permeability properties of fly ash and slag blended HWCs, fly ash replacement reduces the modulus of elasticity of HWC to some extent. A simple relationship was used to estimate the elastic modulus of fly ash and slag based HWCs from their density and compressive strength, and the estimated values agreed well with the experimental results. Experimental investigation shows that the long term drying shrinkage strain for all fly ash based HWCs (15 %–35 %) is lesser than that for the 100 % ordinary portland cement (OPC) and all slag based HWCs. The resultant hardened density variations of fly ash and slag blended concretes exposed to long term controlled environment discussed in this paper can be used for estimating shielding thickness of HWC members against ionizing radiations. The carbonation resistance of fly ash and slag HWCs exposed to 3 % CO2 condition for 146 days is also evaluated. Accelerated carbonation coefficients (kacc) estimated for all types of HWCs show that the carbonation resistance of HWC prepared with 15 % fly ash and 40 % slag is comparable. The rate of accelerated carbonation of HWCs increases for the increase in replacement level of fly ash and slag. In addition to the higher rate of carbonation, increase in calcium carbonate content estimated through micro analytical studies also suggest that a higher level of slag replacement reduces the carbonation resistance of HWC significantly.

Computing of temperature-dependent thermal conductivity and viscosity correlation for solar energy and turbulence appliances via artificial neuro network algorithm

The growing popularity of artificial intelligence approaches has led to their application in a wide range of engineering fields. The most widely used artificial intelligence tool, artificial neural networks, can be used to predict data with high accuracy. An artificial neural network approach is being used to predict effective and accurate thermal conductivity and viscosity models for hybrid nanofluid systems. Here, new types of correlations relating to the thermophysical properties of Fly Ash–Cu nanoparticles with diameter sized 15.2[Formula: see text]nm and which are temperature-dependent are developed. The highest thermal conductivity and viscosity values were obtained for hybrid nanofluids with a mixture ratio of 20:80, with maximum amplification exceeding 83.2% and 65%, respectively, over the base fluid. The Fly Ash–Cu/water hybrid nanofluid’s viscosity and thermal conductivity are evaluated for a concentration range of 0–4%. The evaluation of the Fly Ash–Cu/water hybrid nanofluids system at concentrations ranging from 0 to 4% most likely entails a scientific or engineering study aimed at understanding the behavior and properties of this nanofluid mixture. Nanoparticles can agglomerate or settle in the base fluid over time, compromising the stability of the nanofluids. Researchers may be interested in determining how varied quantities of Fly Ash and Cu nanoparticles affect the nanofluid’s stability and sedimentation behavior. The heat transfer potential is examined within the optimistic range of temperatures of 30–80∘C. Many fruitful results for turbulence and solar energy have been drawn. The Mouromtseff number achieved an optimal value for all concentration levels. The heat transfers of turbulent flow and thermal conductivity of hybrid nanofluids increase with the augmented values of concentrations and temperature. Researchers found an increase in thermal conductivity of hybrid nanofluids at 0–4% concentrations, potentially impacting heat transfer applications. The conclusion explores the potential integration of the developed correlations and neural network model into practical engineering or industrial applications involving solar energy and turbulence appliances. In this work, we extend the work of Kanti et al. [Sol. Energy Mater. Sol. Cells 234 (2022) 111423] which is on the properties of water-based fly ash-copper hybrid nanofluid for solar energy applications.

Semi-quantitative analysis study of the impact of microwave treatment on fly ash

Pre-processing provides an effective way for fly ash's high value-added utilization. However, the shortcomings of pre-processing methods such as grinding and flotation are apparent, with many disadvantages that make it more challenging to use efficiently. Microwave heating helps the SiO2-Al2O3 bond break, not only can make the structural change of the material can also promote the chemical reaction process. In the article, XRD, SEM, FT-TR, ammonia nitrogen adsorption, and other methods were used to analyze the changes in the properties of fly ash before and after microwave pre-treatment, the change of adsorption performance of fly ash before and after microwave treatment was analyzed. The study found that under microwave conditions of 600W and 15min, the adsorption rate of ammonia nitrogen by fly ash reached the maximum of 29.67%. The intensity of mullite and amorphous diffraction peaks decreased after 20 minutes at 600W. The Si-O-(Si, Al) and Si-O-(Si) bonds showed significant changes at 15 and 20 minutes under 600W conditions. Based on the results, microwave conditions were selected at 600W for different periods, and semi-quantitative analysis was carried out by XRD-Rietveld, infrared peak fitting, and nuclear magnetic resonance. The XRD-Rietveld analysis showed that the amorphous phase content reached 46.18% at 15 minutes. In the infrared peak fitting, the fitting area at 1300-900cm-1 and 600-400cm-1 peaks reaches 56.92% at 25 minutes and 17.5% at 15 minutes, respectively. The silicon-oxygen network's degree of connection and polymerization is reduced after 15 minutes of microwave treatment for the nuclear magnetic resonance analysis.

Sustainability study of mix design of high-strength concrete based on fly ash

Concrete is the most widely used building material in the construction of buildings, bridges, highways, and other infrastructure. With the spread of environmental preservation ideas and technological improvement, high-strength concrete materials and their sustainable hybrid design methods have been developed. A sustainable mix design approach for high-strength concrete (HSC) is critical for the construction industry as it is one of the major emitters of CO2 emissions worldwide. Fly ash concrete is an environmentally friendly, economical and sustainable building material. This paper analyzes the sustainable mixed design method of fly ash concrete by combining past scholars' research and practical experience. By analyzing the properties of fly ash, theoretical principles, and some sustainable mixed design methods, the properties (such as durability, compressive strength, etc.) of fly ash HSC are studied. It is found that the properties of fly ash HSC and traditional HSC are similar or even stronger in some aspects, which has a good improvement on the compatibility and durability of concrete. In the future, with the progress of science and technology, people will further study fly ash and HSC, and the application of fly ash in HSC will certainly get greater development, and achieve green development and sustainable development while meeting the strength of concrete.

Study on geotechnical performance of high-grade highway subgrade applied with fly ash

The subgrade filling of high-grade highways requires a lot of earth and stone. If the use of fly ash is used for filling, the purpose of reducing the weight of the subgrade and consuming a large amount of industrial solid waste can be achieved. In order to ensure that fly ash has the possibility of filling, it is necessary to systematically study the road geotechnical properties of fly ash. In this paper, the low liquid limit silty silica-alumina fly ash is taken as the research object, and the road geotechnical properties of fly ash are studied through laboratory tests. The results of the compaction test show that the maximum dry density and optimum moisture content have an obvious linear relationship with the increase in the proportion of fly ash. Small, conducive to the stability of the roadbed. The shear strength of fly ash mainly depends on the internal friction angle, which is much larger than that of ordinary clay. The above test conclusions can provide reference for scientific and economical treatment of fly ash subgrade.

Comparison of the Properties of Coal Gasification Fly Ash and Pulverized Coal Fly Ash as Supplementary Cementitious Materials

Using industrial waste as part of the raw material to produce cement-based materials is considered to be a sustainable cement and concrete materials production method. Coal gasification fly ash (hereafter CGFA) is a solid waste produced during the coal gasification process. Similar to pulverized coal fly ash (hereafter PCFA), it is also a kind of fly ash discharged from combustion coal furnaces. With the development of coal gasification technology, more and more CGFA needs to be treated. Based on the successful experience of PCFA as a supplementary cementitious material in cement-based materials, CGFA is used as a supplementary cementitious material in this paper. A comparison of the performance of two coal-based fly ashes as a supplementary cementitious material (hereafter SCM) was conducted. The effects of two fly ashes on the fluidity and strength of cement mortar were discussed, and the mechanism was analyzed from the mineral composition and morphology of hydration products. At the same time, the properties of CGFA and ultrafine CGFA (UFCGFA) as an SCM were compared. The results show that CGFA has more negative effects on the fluidity of cement mortar than PCFA. But it has a greater contribution to the strength of cement mortar than PCFA. X-ray diffraction (XRD) and scanning electron microscopy (SEM) results show that the active components of CGFA participate in the hydration reaction faster, showing a stronger pozzolanic reactivity than PCFA. Ultrafine treatment of CGFA not only improves the pozzolanic activity but also reduces the negative effect on the fluidity of cement mortar. The contribution of UFCGFA to the fluidity and strength of cement mortar can be greatly improved.

Properties of alkali-activated slag and fly ash blended sea sand concrete exposed to elevated temperature

Alkali-activated slag and fly ash (FA)-blended seawater sea sand concrete (AASC) is a new type of concrete produced without Portland cement or river sand. The advantages of utilising industrial waste and marine resources are that they are not only eco-friendly but cost-saving. This study aimed to investigate the properties of AASC exposed to elevated temperatures. Slag and FA were activated using NaOH and water glass solutions for mixing AASC. Heating and compressive tests were conducted to analyse the thermal and compressive properties of the AASC. The results showed that the AASC with higher FA content (Type II) had fewer flaky structures and more integral interfacial transition zones than the other type of AASC (Type I) after exposure to 600 °C. Type I AASC had better mechanical performance at temperatures below 400 °C but was inferior to Type II AASC beyond 600 °C. A compressive constitutive model was proposed for AASC.

An integrated approach of bioleaching-enhanced electrokinetic remediation of heavy metals from municipal waste incineration fly ash using Acidithiobacillus spp

Introduction: Municipal solid waste (MSW) incineration fly ash is a harmful residue formed during the incineration process. It contains high concentrations of hazardous heavy metals, such as lead, zinc, aluminum, and iron.Methodology: In this study, bioleaching integrated with an electrokinetic approach for heavy metal remediation from MSW incineration fly ash using Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans bacteria was tested.Results and discussion: The physicochemical properties of fly ash included a particle size of 26.1 μm, with the presence of heavy metals. A. ferrooxidans and A. thiooxidans produced sulphuric acid (0.0289 M and 0.0352 M) during the proliferation; this acid enhances the bioleaching of heavy metals from fly ash. The results of an integrated approach showed an 85%, 47%, 92%, 85%, 46%, 67% 11%, and 55% removal of the heavy metals K, Na, Ca, Mg, Al, Zn, Pb, and Mg, respectively, in the presence of A. ferrooxidans. Overall, these results evidenced that heavy metals were completely removed from the fly ash using an integrated approach. Therefore, this integrated approach can be used as an effective heavy metal removal method for treating fly ash in MSW.