Different Types Of Fly Ash Research Articles

Innovative assessment of reactivity in fly ash: The role of particle size distribution characteristics

The relationship between the intrinsic properties of seven different types of fly ash and the compressive strength of the resulting geopolymers was investigated. A comprehensive examination of the effect of chemical and mineralogical compositions, particle size distribution, on the compressive strength of the fly ash-based geopolymers were performed. Results revealed that particle size distribution had a more significant impact on reaction activity than amorphous phase content or average particle size alone. Therefore, a novel concept of 'reaction volume' based on the geopolymerization reaction mechanism was proposed, which reveals a high correlation between the reactivity of fly ash and the compressive strength of geopolymers, thereby enhancing the predictability of the process. The degree of reactivity, formulated through the integration of reaction volume and amorphous silica-aluminum content, was identified as a robust predictor of compressive strength, which can serve as a crucial tool for evaluating fly ash for the production of alkali-activated materials.

Stabilization effect of chelating agents on heavy metals in two types of municipal solid waste incineration fly ash

Municipal solid waste incineration (MSWI) fly ash is complex in composition and contains large amounts of heavy metals. To investigate the effects of different passivating agents on Cd, Pb, Cr, Ni and Zn in different types of fly ash, 7 reagents were selected as passivating agents, including 3 inorganic reagents (Na2S, Na3PO4, NaH2PO4) and 4 organic reagents (SDD, DDTC, TMT, thiourea). The results showed that at low addition levels, sulfur-containing organic chemicals and phosphates were more effective in chelating these metals in both grate furnace incineration fly ash (GF FA) and circulating fluidised bed incineration fly ash (CFB FA), while Na2S was more effective in chelating heavy metals in CFB FA. In addition, agents containing -N-CS groups showed better chelation of heavy metals in GF FA, while heavy metals in CFB FA were more affinity to agents containing -SH groups. The ternary compound TMT-NaH2PO4-SDD (m1:m2:m3 = 2:3:1) was an excellent chelating agent for Pb, Cd in the GF FA, and TMT-Na2S-thiourea (m1:m2:m3 = 2:1:3) was a suitable chelating agent for these metals in CFB FA. The chelation rate of Cd and Pb after the treatments mixed ternary reagents was above 99%, and the leaching amount was much lower than the limit value of pollution control standards for domestic landfills. Moreover, under different pH leaching conditions, the leaching concentrations of Cd and Pb in the fly ashes treated with the ternary mixture were lower than the standard limits. In general, the ternary compound can effectively chelate heavy metals in fly ash, which provides a reference for selecting a suitable stabilizer combination for heavy metal in fly ash.

Comparative environmental assessment of low and high CaO fly ash in mass concrete mixtures for enhanced sustainability: Impact of fly ash type and transportation

The effect of fly ash type on the sustainability of concrete mixtures has yet to be quantified. This study aims to assess the environmental impacts of low calcium oxide (CaO) and high CaO fly ash in mass concrete mixtures from Thailand. The study analyzed 27 concrete mixtures with varying percentages of fly ash as a cement replacement (0%, 25%, and 50%) for 30 MPa, 35 MPa, and 40 MPa compressive strengths at specified design ages of 28 and 56 days. Sources of fly ash have been located between 190 km and 600 km away from batching plants. The environmental impacts were assessed using SimaPro 9.3 software. The global warming potential of concrete is reduced by 22–30.6% and 44–51.4% when fly ash, regardless of type, is used at 25% and 50%, respectively, in comparison with pure cement concrete. High CaO fly ash has more environmental benefits than low CaO fly ash when utilized as a cement substitute. The reduction in environmental burden was most significant for the midpoint categories of mineral resource scarcity (10.2%), global warming potential (8.8%), and water consumption (8.2%) for the 40 MPa, 56-day design with 50% fly ash replacement. The longer design age (56 days) for fly ash concrete showed better environmental performance. However, long-distance transport significantly affects ionizing radiation and ecotoxicity indicators for terrestrial, marine, and freshwater environments. Furthermore, the results show that a high cement replacement level (50%) may not always have a reduced environmental impact on mass concrete when considering long-distance transportation. The critical distance calculated based on ecotoxicity indicators was shorter than those calculated using global warming potential. The results of this study can provide insights for developing policies to increase concrete sustainability using different types of fly ash.

Effect of Activator Type on Geopolymer Mortars Containing Different Types of Fly Ash

In this study, the influence of the activator type on the physical and mechanical properties of the geopolymer mortars was analyzed. C and F-class fly ash (FA), blast furnace slag (BFS), sodium hydroxide (NH), sodium metasilicate (NS), standard sand, and distilled water were used in the production of mortar specimens. All specimens were cured at room temperature. C and F-class fly ash usage ratios are 0%, 15%, and 30%. NH was used as an activator in the 1st group of the produced geopolymer mortars, and NS with NH was used in the 2nd group. 5 series were produced and a flow-table test, ultrasonic pulse velocity test, flexural strength test, compressive strength test, and Scanning Electron Microscope-Energy Dispersive Spectrometry (SEM-EDS) microstructure analysis were applied to the samples. The addition of NS increased the compressive strength and the greatest increase occurred in the reference sample by 113%. It also increased the compressive strength of FAF30 by 60% in comparison to FAC30. Following the results of the SEM examination, when the reference samples were compared, the addition of NS inhibited the formation of cracks. According to the SEM-EDS analysis results, an increase in the F and C-class FA ratio improved the crack formation. Compared to F-class FA, FAC30 has more cracks due to the lower SiO2 content in C-class FA. High K content and SiO2 ratio, as determined by EDS analysis, boost the alkalinity and positively impact the strength.

Study on Mechanical and Rheological Properties of Solid Waste-Based ECC

As one of the main raw materials of engineered cementitious composite (ECC), fly ash exerts the “ball effect” and “pozzolanic effect” in concrete, which improves the working performance of concrete and enhances the strength of the concrete matrix. Polyvinyl alcohol (PVA) fiber has been widely used in the preparation of ECC, while ground fly ash can be used to enhance the performance of ECC as a kind of high-activity admixture. In this paper, the compressive strength, flexural strength and flexural toughness of ECC prepared from different types of fly ash (raw fly ash, sorted fly ash and ground fly ash) are compared, and the rheological properties of the ECC are analyzed by studying the two parameters of yield stress and plastic viscosity. The results show that the smaller the particle size of fly ash is, the more sufficient it reacts with Ca(OH)2 produced by cement hydration, and the more it can improve the compressive strength and flexural strength of the matrix. In addition, the smaller the particle size of fly ash, the higher the yield stress and plastic viscosity of ECC; therefore, the distribution of PVA fiber in ECC is more uniform, thereby improving the flexural toughness and ductility of ECC.

Physical and Mechanical Properties of Alkali Activated Mortars Produced Using Different Types of Fly Ash

Çimento üretimi sırasında atmosfere salınan karbondioksit (CO2), küresel ısınmaya neden olan önemli faktörlerden biridir. Bu nedenle, çimento tüketimini azaltmak amacıyla farklı malzemelerin kullanımı önem kazanmıştır. Bu amaçla alkalilerle aktive edilmiş malzemelerin (AAM) kullanımı oldukça yaygınlaşmaktadır. Bu çalışmada; yüksek fırın cürufu (YFC) ve 2 farklı tipte uçucu kül (UK) ile üretilen alkaliyle aktive edilmiş harçların fiziksel ve mekanik özellikleri araştırılmıştır. Harçlar; Tunçbilek Termik Santrali'nden temin edilen F sınıfı UK ile Çayırhan Termik Santrali'nden elde edilen C sınıfı UK, CEN referans kumu, YFC, sodyum hidroksit (NaOH), distile su ve kimyasal katkı maddesi kullanılarak üretilmiştir. Su/bağlayıcı ve kum/bağlayıcı oranı sırasıyla 0.5 ve 3 olarak alınmıştır. UK; YFC ile ağırlıkça %0, %10, %20, %30 ve %40 oranlarında yer değiştirilerek kullanılmıştır. Alkaliyle aktive edilmiş harç numunelerinin 1. serisine; 28 gün boyunca 21±1˚C’de sızdırmazlık kürü, 2. serisine ise 2 gün boyunca 105±5˚C’de ısıl kür ve 26 gün boyunca 21±1 ˚C’de sızdırmazlık kürü uygulanmıştır. Alkaliyle aktive edilmiş harç numunelerinin yayılma değeri, ağırlıkça su emme oranı, boşluk oranı, eğilme dayanımı ve basınç dayanımı belirlenmiştir. Çalışma sonucunda 1. ve 2. seride YFC100’e en yakın basınç dayanımı UKF10’da elde edilmiştir.

Effects of Composition Type and Activator on Fly Ash-Based Alkali Activated Materials.

The compressive strengths of fly ash-based alkali-activated materials (AAM), produced using various activators of only sodium hydroxide, were measured. Fly ash-based AAM specimens, produced by mixing different kinds of fly ash and ground granulated blast-furnace slag (GGBFs) with an activator containing only sodium hydroxide, were cured at ambient temperature, and then placed in air for different numbers of days. The short- and long-term compressive strengths and shrinkage of fly ash-based AAM were measured and compared to one another. The effects of type of fly ash, alkali-equivalent content, GGBFs replace percentage, and ages on the compressive strengths and shrinkage of fly ash-based AAM were investigated. Even when different fly ash was used as the raw material for AAM, a similar compressive strength can be achieved by alkali-equivalent content, GGBFs replaces percentage. However, the performance of shrinkage due to different types of fly ash differed significantly.

Influence of Water Retention Curves Model Fitting Parameters on Unsaturated Seepage Modeling of Fly Ashes and Pond Ashes

Water retention curves (WRC) and its fitting parameters are important inputs for conducting unsaturated seepage modeling study in any geotechnical and geo-environmental problems. This study investigated the effect of variation in WRC model fitting parameters on unsaturated seepage modeling behavior for different types of fly ashes and pond ash. A transient seepage analysis was carried out in a one-dimensional cylindrical column using a finite element method-based software SEEP/W, under a specified total head (H) boundary condition. The variation in pore water pressure (PWP) and volumetric water content (VWC) with time was studied for different conditions. It was found that both PWP and VWC variation with time got affected when WRC model fitting parameters of different fly ashes were used. The influence of suction measurement range on unsaturated seepage modeling result was also found to be considerable. It was established from this study that variation in PWP with time for different fly ashes was mainly due to the variation in the WRC model fitting parameters since the saturated hydraulic conductivity (ksat) value of all the fly ashes was comparable. Further, the sensitivity of Fredlund and Xing (Can Geotech J 31(3): 521–532, 1994) model parameters was studied in detail based on their standard deviations. The study showed that sensitivity on seepage modeling results drastically reduces beyond 20% variation from the reference mean value.

Polymer repair products containing fly ash contaminated by denitrification process

The increase in the emphasis on the quality and long life of buildings and structures opens space for the development of new and progressive renovation materials. Current trends focus on using the by-products of thermal powerplants, fly ash (FA), produced by the combustion of pulverised coal, which is contaminated by the denitrification of the fumes. Because ammonia escapes from the concrete containing contaminated fly ash, further use of the fly ash in concrete or as a partial cement replacement is problematic. The most advantageous use of FA seems to be as a filler in polymerous materials. For this reason, this paper focuses on verifying new ways of using FA as a filler in polymer mortars and concretes, which are then used as structural and non-structural repair products and systems, according to the European Standard EN 1504–1. By studying four different types of FA, we found that FA, neither from high-temperature combustion nor fluid, contaminated by flue gas denitrification process does not deteriorate the properties of epoxy resin polymer repair products. Successful use of these by-products was proved by comparing the results of the physical and mechanical parameters of the polymer mortars containing contaminated FA with the reference polymer mortars containing only primary raw materials and polymer mortars with FA unaffected by the denitrification process. Computed tomography (CT) was used to analyse the microstructure and bond strength of the developed materials to underlying concrete surface; it was also confirmed that weather does not degrade the developed materials. Scanning electron microscopy (SEM) supported by dispersion spectral analysis proved that distribution of individual elements of filler in the developed repair products is even and FA particles were successfully incorporated in the enclosed structure of the polymer matrix. New materials are economically beneficial because a large amount of by-products are used in their composition (up to 60% by weight). They are capable of replacing a considerable proportion of the epoxy resin, which is the most expensive component of the material. In this way, a new possibility was developed for using contaminated FA as well as new polymer repair products and systems with excellent parameters.

The denitration mechanism of fly ash catalysts prepared by low-temperature plasma technology

In this paper, fly ash-based catalysts were supported by equivalent-volume impregnation method and roasted with low-temperature plasma technology. This technology has the advantages of short treatment time, lower energy consumption, and well-distributed active components. Therefore, the plasma power, plasma time, oxygen flow rate and metal loading condition in the denitration process were studied at sub-atmosphere ambient gas processing conditions. Different types of fly ash, modification conditions and loading conditions in the denitration process were studied. BET, XRD, SEM and XPS were used to characterize the catalysts, and the effect of the structure and performance of catalysts during the catalytic activity of the catalysts were further determined. The results were: The manganese metal and cerium metal were successively loaded in the catalyst and then roasted in low temperature plasma with oxygen. The two metals had a synergistic effect on forming P-type semiconductors, which significantly improved the performance of denitration. MnO2 and CeO2 played a major role in denitration. The fly ash-based catalyst with the preliminary modification and then loaded metal oxides not only maintained effective denitration performance, but also greatly improved the sulfur resistance, and had a positive effect on extending the service life of catalysts.

Ternary Diagrams for Predicting Strength of Soil Ameliorated with Different Types of Fly Ash

In recent years, the use of geopolymer materials for ground improvement has increased with the growth in the construction sector. The lignite coal used in the thermal power plants in Turkey has low-calorie content. Thus, fly ash from these thermal power plants has high-lime content, making it unsuitable for cement production or as a cement additive material. Therefore, it is necessary to find different areas where fly ash can be utilised. In this study, the fly ashes of six power plants were tested to improve the properties of cohesive soil. The effects of fly ash along with the soil properties on improving the physicomechanical properties of the soil were examined with different mix designs. The effects of the curing period on the soil strength values were examined, and the unconfined compressive strength values of all mixtures were compared with those of the controlled specimens prepared with optimum water content. In the literature, seventeen various case studies on fly ash–soil remediation have been investigated. The data of this study and other studies were evaluated together, and multiple regression and artificial neural network analyses were performed to estimate the improved soil strength. Additionally, ternary contour diagrams were designed for assessing the fly ash–mixed soil strength using the physical and mechanical properties of the soil and fly ash.

NANO SİLİKA KÜR UYGULAMASININ ÇİMENTO BAĞLAYICILI KOMPOZİTLERİN DONMA-ÇÖZÜLME DİRENCİ ÜZERİNE ETKİSİNİN ARAŞTIRILMASI

Bu çalışmada nano silica solüsyonunda kür etkisine maruz bırakılan çimento bağlayıcılı kompozitlerin (ECC), donma-çözülme döngüleri gibi ağır çevresel koşullar altında gösterdikleri direnç araştırılmıştır. Bu amaçla iki farklı tip uçucu kül iki farklı oranda kullanılarak dört farklı karışım olarak hazırlanan ECC numuneleri, ASTM C666 ProsedürA’ya uygun olarak 300 donma-çözülme döngüsüne maruz bırakılmıştır. Numunelerin mekanik özelliklerindeki değişimler basınç ve eğilme testleri ile, fiziksel özelliklerindeki değişimler ise, 30 çevrimde bir ağırlıklarının ölçülmesi ile belirlenmiştir. Çalışma neticesinde elde edilen sonuçlar, çimento bağlayıcılı kompozitlerde nano silica (NS) kür uygulamasının, zorlayıcı çevresel koşullar altında numunelerin dayanım ve dayanıklılık gibi özelliklerinde suda kür uygulamasına göre kayda değer artışlar sergilediğini göstermiştir.

Mechanical activation of two different types of fly ash and their effect on alkali activation.

The article aim is to analyze the influence of mechanical activation of a fly ash, with different proportion of mechanically activated and not mechanically activated material on alkali activation. The paper describes fly ash based geopolymers and their mechanical properties. Fly ashes were mixed in four different ratios with mechanically activated fly ash. Activation solution was constant in all specimens. Compressive and flexural strengths of the hardened product were tested after 7 and 28 days of the storage in laboratory conditions and samples were cured after activation in hot air chamber for 6 hours in 80°C temperature. The results show how mechanical activation of materials affects their strengths with highest amount achieved was 44 MPa.

Effect of fineness and calcium content of fly ash on the mechanical properties of Engineered Cementitious Composites (ECC)

Abstract As a new green material, ECC has received extensive attention all over the world because of its potent ability of crack width controlling, excellent behavior of flexural toughness, and fatigue durability. The use of high volume fly ash as a partial replacement of cement reduces environmental pollution and conserves natural resources. This paper presents the experimental results to find out the effect of fineness and calcium content of fly ash on the mechanical properties of ECC. Four different types of fly ash were used and a series of mechanical tests, including cube compressive strength, uniaxial direct tensile, three-point bending and single-crack tension tensile were conducted in this paper. The results indicate that between tensile strain properties and fly ash fineness, there is not just a simply linear relationship. Fineness is not the determining factor for ECC’s compression performance, but the activity of fly ash. Fly ash with the higher calcium content did not make the tensile properties of ECCs greater at all ages, but make compressive performance better.

Influences of different types of fly ash and confinement on performances of expansive mortars and concretes

Abstract This paper evaluates the performances of expansive concrete containing fly ashes. In this study, both standard fly ashes and substandard fly ash are used as a cement replacing material in expansive mortar and concrete. A substandard fly ash which contains high CaO, free lime, and SO3 contents is used in this study to compare it with high CaO and low CaO fly ashes which are standard fly ashes. Flow, water requirement, and setting times of the expansive mortars are studied together with unconfined and confined compressive strength, length changes, and Young’s modulus of expansive concretes. Test results indicate that both free expansion and restrained expansion of the expansive concrete are enhanced by using fly ash, especially by the substandard fly ash. Three hypotheses supporting the mechanism of fly ash on the expansion enhancement of the mixtures are described. The first hypothesis is that expansive mixtures containing fly ash produce more ettringite than that without fly ash. The second hypothesis is that a smaller stiffness leads to a higher expansion of the expansive concrete containing fly ash when compared to that of the expansive concrete without fly ash. The third hypothesis is that fly ash delays the hydration of the expansive additive in the expansive mixtures. These hypotheses are clarified by the test results of XRD-Rietveld analysis, DTG, and Young’s modulus. The use of fly ash in the expansive concrete enhances the expansion, the compressive strength, and the pore structure, especially for the expansive concrete under confinement. A mercury intrusion porosimetry (MIP) test of mortar is used to verify the enhanced compressive strength and the pore structure of the expansive concretes.

Characterization of different types of fly ash collected from various sources in Central India

Abstract The proper management of a vast amount of fly ash generated by various industries is of economic and environmental importance. The current study characterizes six different types of fly ash to understand their potential as a building material. The different types of fly ash were characterized by employing X-ray Diffraction (XRD) and identifying the presence of different compounds. In the end, conclusions were drawn to recommend the potential application area for the different types of fly ash.

Mechanical properties of alkali activated geopolymer paste using different Romanian fly ash sources – experimental results

As concrete demand is constantly increasing in recent years and also considering that cement production is both a consumer of natural resources and a source of carbon dioxide release into the atmosphere, there have been worldwide investigations into green alternatives for making concrete environmentally friendlier and simultaneously to satisfy the development of infrastructure facilities. The use of fly ash as a component of cementitious binders is not new but when considering the specific case of alkaline activation and fly ash representing the only source for the binder formation, it necessitates a more complete understanding of its specific reactions during the alkaline activation process. Since the fly ash varies dramatically, not only from one source to another, but also from one batch to another even when provided by the same power plant, its chemistry in obtaining alkali-activated materials during the geopolymerisation process and the final mechanical properties are considered crucial for the performance of geopolymer concrete. This paper will provide a review of the experimental results concerning the physical and mechanical evaluation of the alkali-activated fly ash-based geopolymer materials, developed with different types of fly ash, for a better understanding of geopolymer concrete production control.

Effect of Different Types of Fly Ash on Properties of Asphalt Mixtures

In order to preserve natural resources, the use of waste and alternative materials in the construction and maintenance of roads is increasingly investigated. This paper presents the results of testing wearing course asphalt mixtures (AC 11s SURF 50/70) made with various percentages of fly ash, used as a partial or complete substitute for mineral filler. The properties of fly ash were determined to assess their suitability for use in asphalt mixtures. The experimental research was performed on asphalt samples containing fly ash from three different sources, with 25%, 50%, 75%, and 100% of mineral filler substitution. The control mixture was prepared with 100% of mineral filler. The paper presents the volumetric composition, stability, and flow of asphalt mixtures tested on standard Marshall’s samples, water sensitivity, and resistance to permanent deformation. The results of this study indicate that a satisfactory volumetric composition can be achieved by adding fly ash, while the bulk density and voids of the mineral and asphalt mixture generally depend on the type of fly ash and its content. The stability and flow of mixtures with fly ash are favourable compared with the control mixture. The water sensitivity of mixtures with fly ash is generally lower compared with the control mixture and depends on the type and percentage of fly ash. The resistance to permanent deformation of the asphalt mixtures depends on the fly ash type and percentage. The results obtained in this study are an important step towards broader implementation of fly ash in asphalt mixtures.

APPEARANCE FEATURES OF CLAYEY MIXTURES HAVING FLY ASHES

The use of wastes has become very significant and widespread in terms of sustainable production of clayey mixtures, since the wastes provide many advantages. In this study, the effects of two different types of fly ash, which were wastes of Seyitomer and Cayirhan thermal power plants, on the color change of brick samples with various amount of fly ash ranging between 0 to 60% at different sintering temperatures were investigated. As a result, traditional red colored bricks could be produced with fly ash without using a separate raw material to meet the color requirements. It was found that desired colors for special architectural applications could also be achieved by using fly ash.

Greenhouse gas emissions of different fly ash based geopolymer concretes in building construction

Replacing virgin materials with recycled or sustainable materials to reduce energy consumptions and emissions is the focus of contemporary research to reduce building related emissions. Geopolymer concrete produced using 100% fly ash is a similar sustainable construction material capable of replacing Portland Cement (PC) concrete. As a replacement for PC, fly ash seems to be a sustainable solution, however the benefits from the production process of fly ash geopolymer (FAGP) concrete is the subject of considerable debate. In addition, factors such as local availability and transportation issues could potentially increase the emission profile of FAGP concrete. Thus, this study aims to evaluate the emission profiles for different types of fly ash in Australia considering availability and transportation. A case study and a scenario analysis are also presented to demonstrate the factors that affect the Green House Gas (GHG) emission profile of FAGP manufacture. The results indicate that to the GHG emission profile for FAGP concrete changes considerably based on the material availability, transportation and mix design. Alkali activators and elevated heat curing processes also significantly contribute the total GHG emissions of FAGP concrete production. The results further signify that the case study location could influence the employment of FAGP concrete in terms of GHG emissions. Further studies are encouraged on optimising the cost, GHG emissions, availability and strength characteristics to strike a balance between in sustainability for selecting the best FAGP type for construction. The results also provide the initial factors to be considered in developing a guideline for employing sustainable materials in the building industry.