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Effects of sulfur on variations in the chemical speciation of heavy metals from fly ash glass

《环境科学与工程前沿（英文）》 2023年 第17卷 第10期 doi: 10.1007/s11783-023-1728-7

摘要：

● A higher sulfur content reduced the curing rate of Cr in glass.

关键词： Dechlorinated fly ash     SO3     Heavy metal     Chemical speciation     Glass solidification    

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Service life prediction of fly ash concrete using an artificial neural network

《结构与土木工程前沿（英文）》 2021年 第15卷 第3期   页码 793-805 doi: 10.1007/s11709-021-0717-9

摘要： Carbonation is one of the most aggressive phenomena affecting reinforced concrete structures and causing their degradation over time. Once reinforcement is altered by carbonation, the structure will no longer fulfill service requirements. For this purpose, the present work estimates the lifetime of fly ash concrete by developing a carbonation depth prediction model that uses an artificial neural network technique. A collection of 300 data points was made from experimental results available in the published literature. Backpropagation training of a three-layer perceptron was selected for the calculation of weights and biases of the network to reach the desired performance. Six parameters affecting carbonation were used as input neurons: binder content, fly ash substitution rate, water/binder ratio, CO2 concentration, relative humidity, and concrete age. Moreover, experimental validation carried out for the developed model shows that the artificial neural network has strong potential as a feasible tool to accurately predict the carbonation depth of fly ash concrete. Finally, a mathematical formula is proposed that can be used to successfully estimate the service life of fly ash concrete.

关键词： concrete     fly ash     carbonation     neural networks     experimental validation     service life    

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Direct synthesis of carbon nanotubes on fly ash particles to produce carbon nanotubes/fly ash composites

Fangxian LI, Cheng ZHOU, Pengfei YANG, Beihan WANG, Jie HU, Jiangxiong WEI, Qijun YU

《结构与土木工程前沿（英文）》 2019年 第13卷 第6期   页码 1405-1414 doi: 10.1007/s11709-019-0564-0

摘要： Fly ash was used as catalytic support for carbon nanotubes (CNTs) growth by chemical vapor deposition (CVD) due to having ideal compositions (SiO , Al O , and Fe O ). In this paper, CNTs were synthesized on Ni catalyst/fly ash substrate using CVD method. The influence of parameters (e.g., reaction temperature and gas flow rate) on the carbon yield and structure of the resulting CNTs was on the carbon yield and structure of the resulting CNTs was investigated by thermo-gravimetric analyses, Scanning electron microscopy, and Raman spectroscopy analysis. The results indicated that the growth temperature controlling had a significant effect on the diameter of CNTs. And the proper acetylene and hydrogen flow rate would decrease in defect density and increase in yield of as-grown CNTs on fly ash. Finally, the amorphous carbon on the surface of as-grown CNTs were removed by heating in air. Experimental results showed that the hydrophobic of the annealed CNTs was weak due to introducing functional groups to the surface of CNTs.

关键词： carbon nanotubes     fly ash     chemical vapor deposition     parameters     purification    

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Effect of fly ash replacement level on the fracture behavior of concrete

Mahdi AREZOUMANDI, Jeffery S. VOLZ

《结构与土木工程前沿（英文）》 2013年 第7卷 第4期   页码 411-418 doi: 10.1007/s11709-013-0228-4

摘要： The production of portland cement–the key ingredient in concrete–generates a significant amount of carbon dioxide. However, due to its incredible versatility, availability, and relatively low cost, concrete is the most consumed manmade material on the planet. One method of reducing concrete’s contribution to greenhouse gas emissions is the use of fly ash to replace a significant amount of the cement. ?This study presents the results of an experimental investigation that evaluates effect of fly ash replacement level on the fracture energy of concrete. This study includes four mixes with 0%, 30%, 50%, and 70% fly ash as a cement replacement. This experimental program consisted of 32 fracture beams to study the fracture behavior of concrete. The experimental fracture energies were compared with the fracture energy provisions of different design codes and also different analytical equations. Furthermore, statistical data analyses (parametric and non-parametric) were performed to evaluate whether or not there is any statistically significant difference between the experimental fracture energies of different mixes. Results of these statistical tests show that the mix with higher level of fly ash replacement level has higher fracture energy.

关键词： concrete     fracture energy     fly ash    

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Accelerated engineering properties of high and low volume fly ash concretes reinforced with glued steel

Vallarasu Manoharan SOUNTHARARAJAN, Dr. Anandan SIVAKUMAR

《结构与土木工程前沿（英文）》 2013年 第7卷 第4期   页码 429-445 doi: 10.1007/s11709-013-0226-6

摘要： The present study focuses on the improvement of pozzolanic reaction of fly ash particles with the cement hydration products. Low and high volume fly ash concrete mixtures were studied systematically with the addition of accelerating admixtures and accelerated curing of the concrete specimens in a steam chamber for 18 h at 75°C. Also, the reinforcing effects of glued steel fibers addition on the compressive and flexural performance of fly ash concrete were investigated. The test results indicated that the addition of accelerator improved the rate of hardening and the inclusion of steel fibers provided higher flexural performance. Also, it can be noted that the high volume fly ash (50%) addition in concrete showed a reduction in strength; however, the addition of accelerator has compensated the deceleration in strength gain. The proper selection of concrete ingredients, addition of accelerator and initial steam curing for 18 h showed better improvement on the engineering properties in fly ash concrete. A maximum increase (41.7%) in compressive strength of fly ash concrete around 52.90 MPa was noticed for 25% fly ash substitution and 1.5% steel fibers addition. Dynamic elastic modulus was also calculated in loaded concrete specimen using ultrasonic pulse velocity test and showed a good agreement with the experimental value.

关键词： fly ash     pozzolanic index     steam curing     superplasticizer     accelerator     steel fibres     elastic modulus    

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Effects of seeding nucleation agent on geopolymerization process of fly-ash geopolymer

Lapyote PRASITTISOPIN, Issara SEREEWATTHANAWUT

《结构与土木工程前沿（英文）》 2018年 第12卷 第1期   页码 16-25 doi: 10.1007/s11709-016-0373-7

摘要： Geopolymer, an inorganic aluminosilicate material activated by alkaline medium solution, can perform as an inorganic adhesive. The geopolymer technology has a viability to substitute traditional concrete made of portland cement (PC) because replacing PC with fly ash leads to reduced carbon dioxide emissions from cement productions and reduced materials cost. Although fly ash geopolymer stimulates sustainability, it is slow geopolymerization reaction poses a challenge for construction technology in term of practicality. The development of increasing geopolymerization reaction rate of the geopolymer is needed. ?The purpose of this study is to evaluate seeding nucleation agents (NA) of fly ash geopolymer that can accelerate polymerization reactions such that the geopolymer can be widely used in the construction industry. Results from the present study indicate that the use of NA (i.e., Ca(OH) ) can be potentially used to increase geopolymerization reaction rate and improve performance characteristics of the fly ash geopolymer product.

关键词： fly ash     geopolymer     nucleation agent     portland cement replacement    

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Porous silica synthesis out of coal fly ash with no residue generation and complete silicon separation

《环境科学与工程前沿（英文）》 2023年 第17卷 第9期 doi: 10.1007/s11783-023-1712-2

摘要：

● Both amorphous and crystalline silicon are completely separated from coal fly ash.

关键词： Coal fly ash     Alkali fusion     Micro-/meso-porous Si     Zeolite MCM-48     Crystalline transformation    

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Fresh and hardened properties of high-performance fiber-reinforced concrete containing fly ash and ricehusk ash: Influence of fiber type and content

Nguyen-Trong HO; Viet Quoc DANG; Minh-Hieu NGUYEN; Chao-Lung HWANG; Trong-Phuoc HUYNH

《结构与土木工程前沿（英文）》 2022年 第16卷 第12期   页码 1621-1632 doi: 10.1007/s11709-022-0884-3

摘要： Although fibers are used only infrequently as an additive in concrete in the construction industry, fiber-enhanced concrete is known to provide a wide range of advantages over conventional concrete. The main objective of this study was to investigate the influences of fiber type and content on the mechanical properties and durability of high-performance fiber-reinforced concrete (HPFRC) designed using a novel densified mixture design algorithm with fly ash and rice husk ash. Three types of fiber, including polypropylene (PP) fiber, steel fiber (SF), and hybrid fiber (HF), were considered. Based on the results, the inclusion of fibers decreased HPFRC flowability, regardless of fiber type. Although the compressive strength of HPFRC with 1.6% PP fiber content was 11.2% below that of the reference HPFRC specimen at 91 d of curing age, the 91-d compressive strengths of both SF and HF-enhanced HPFRC specimens were significantly better than that of the reference HPFRC specimen. Furthermore, the HPFRC specimens incorporating SF and HF both exhibited better splitting tensile and flexural strengths as well as less drying shrinkage than the HPFRC specimens incorporating PP fiber. However, the fiber-enhanced specimens, especially those with added SF, registered less surface electrical resistivity and greater vulnerability to chloride ion penetration than the reference HPFRC specimen.

关键词： high-performance fiber-reinforced concrete     fly ash     rice husk ash     durability     mechanical strength    

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The investigation of fly ash based asphalt binders using atomic force microscope

Rajan SAHA, Kyle MALLOY, Emil BAUTISTA, Konstantin SOBOLEV

《结构与土木工程前沿（英文）》 2017年 第11卷 第4期   页码 380-387 doi: 10.1007/s11709-017-0437-3

摘要： Atomic Force Microscope (AFM) is a relatively new technique for investigation of construction materials. In this study AFM was used to investigate the interaction of asphalt binder with fly ash. Fly ash is a coal combustion byproduct of electric power utilities having pozzolanic properties and commonly used in Portland cement concrete. In this study, an investigation was made by using different types of fly ash with two types of asphalt binders such as PG 58-28 and PG 64-28. Asphalt microstructure is divided into four subgroups such as Saturates, Aromatics, Resins and Asphaltenes (SARA). These four phases can be distinguished by the atomic force microscope. The interaction of these phases affected by introducing fly-ash was investigated and correlation with rheological properties was observed.

关键词： AFM     fly ash     bee     rheology     asphalt    

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Chloride binding and time-dependent surface chloride content models for fly ash concrete

S. MUTHULINGAM,B. N. RAO

《结构与土木工程前沿（英文）》 2016年 第10卷 第1期   页码 112-120 doi: 10.1007/s11709-015-0322-x

摘要： Corrosion of embedded rebars is a classical deterioration mechanism of reinforced concrete structures exposed to chloride environments. Such environments can be attributed to the presence of seawater, deicing or sea-salts, which have high concentrations of chloride ion. Chloride ingress into concrete, essential for inducing rebar corrosion, is a complex interaction between many physical and chemical processes. The current study proposes two chloride ingress parameter models for fly ash concrete, namely: 1) surface chloride content under tidal exposure condition; and 2) chloride binding. First, inconsistencies in surface chloride content and chloride binding models reported in literature, due to them not being in line with past research studies, are pointed out. Secondly, to avoid such inconsistencies, surface chloride content and chloride binding models for fly ash concrete are proposed based upon the experimental work done by other researchers. It is observed that, proposed models are simple, consistent and in line with past research studies reported in literature.

关键词： binding isotherms     chloride ingress     concrete     fly ash     surface chloride content    

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Compressive strength and stability of sustainable self-consolidating concrete containing fly ash, silica

Osama Ahmed MOHAMED, Omar Fawwaz NAJM

《结构与土木工程前沿（英文）》 2017年 第11卷 第4期   页码 406-411 doi: 10.1007/s11709-016-0350-1

摘要： This paper presents the findings of an experimental program seeking to understand the effect of mineral admixtures on fresh and hardened properties of sustainable self-consolidating concrete (SCC) mixes where up to 80% of Portland cement was replaced with fly ash, silica fume, or ground granulated blast furnace slag. Compressive strength of SCC mixes was measured after 3, 7, and 28 days of moist curing. It was concluded in this study that increasing the dosage of fly ash increases concrete flow but also decreases segregation resistance. In addition, for the water-to-cement ratio of 0.36 used in this study, it was observed that the compressive strength decreases compared to control mix after 28 days of curing when cement was partially replaced by 10%, 30%, and 40% of fly ash. However, a fly ash replacement ratio of 20% increased the compressive strength by a small margin compared to the control mix. Replacing cement with silica fume at 5%, 10%, 15%, and 20% was found to increase compressive strength of SCC mixes compared to the control mix. However, the highest 28 day compressive strength of 95.3 MPa occurred with SCC mixes in which 15% of the cement was replaced with silica fume.

关键词： fly ash     silica fume     ground granulated blast-furnace slag     self-consolidating concrete     and sustainable concrete    

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Characteristics of the stabilized/solidified municipal solid wastes incineration fly ash and the leaching

Yan SHAO,Haobo HOU,Guangxing WANG,Sha WAN,Min ZHOU

《环境科学与工程前沿（英文）》 2016年 第10卷 第1期   页码 192-200 doi: 10.1007/s11783-014-0719-0

摘要： Fly ash is a hazardous byproduct of municipal solid wastes incineration (MSWI). An alkali activated blast furnace slag-based cementitious material was used to stabilize/solidify the fly ash at experimental level. The characteristics of the stabilized/solidified fly ash, including metal leachability, mineralogical characteristics and the distributions of metals in matrices, were tested by toxic characteristic leaching procedure (TCLP), X-ray diffraction (XRD) and scanning electron microscopy-energy dispersive spectrometer (SEM-EDS) respectively. Continuous acid extraction was utilized to extract metal ions and characterize their leaching behavior. The stabilization/solidification procedure for MSWI fly ash demonstrates a strong fixing capacity for the metals by the formation of C-S-H phase, hydrated calcium aluminosilicate and ettringite. The stabilized/solidified fly ash shows a dense and homogeneous microstructure. Cr is mainly solidified in hydrated calcium aluminosilicate, C-S-H and ettringite phase through physical encapsulation, precipitation, adsorption or substitution mechanisms, and Pb is mainly solidified in C-S-H phase and absorbed in the Si-O structure.

关键词： municipal solid waste incineration (MSWI) fly ash     blast furnace slag     leaching behavior     Cr     Pb    

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Mercury emission and adsorption characteristics of fly ash in PC and CFB boilers

Li JIA, Baoguo FAN, Xianrong ZHENG, Xiaolei QIAO, Yuxing YAO, Rui ZHAO, Jinrong GUO, Yan JIN

《能源前沿（英文）》 2021年 第15卷 第1期   页码 112-123 doi: 10.1007/s11708-020-0682-3

摘要： The mercury emission was obtained by measuring the mercury contents in flue gas and solid samples in pulverized coal (PC) and circulating fluidized bed (CFB) utility boilers. The relationship was obtained between the mercury emission and adsorption characteristics of fly ash. The parameters included unburned carbon content, particle size, and pore structure of fly ash. The results showed that the majority of mercury released to the atmosphere with the flue gas in PC boiler, while the mercury was enriched in fly ash and captured by the precipitator in CFB boiler. The coal factor was proposed to characterize the impact of coal property on mercury emissions in this paper. As the coal factor increased, the mercury emission to the atmosphere decreased. It was also found that the mercury content of fly ash in the CFB boiler was ten times higher than that in the PC boiler. As the unburned carbon content increased, the mercury adsorbed increased. The capacity of adsorbing mercury by fly ash was directly related to the particle size. The particle size corresponding to the highest content of mercury, which was about 560 ng/g, appeared in the range from 77.5 to 106 µm. The content of mesoporous (4–6 nm) of the fly ash in the particle size of 77.5–106 µm was the highest, which was beneficial to adsorbing the mercury. The specific surface area played a more significant role than specific pore volume in the mercury adsorption process.

关键词： mercury     combustion modes     coal property     fly ash     particle size    

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Establishing two-stage interaction between fly ash and NaOH by X-ray and infrared analyses

Bhagwanjee JHA,Nevin KOSHY,Devendra Narain SINGH

《环境科学与工程前沿（英文）》 2015年 第9卷 第2期   页码 216-221 doi: 10.1007/s11783-014-0630-8

摘要： The interaction of the fly ash and NaOH, in an open reflux hydrothermal system at 100°C, has been explored by several researchers and formation of fly ash zeolites has been confirmed based on the X-ray diffraction analysis of the residues. However, this method does not reveal much about the characteristic transitions (viz. elemental, electro-negativity and cation exchange capacity) of the residues. In this situation, resorting to Fourier transform-infrared radiation (FT-IR) spectroscopy on the residues obtained from two-stage hydrothermal treatment process, described in this manuscript, appears to be a novel idea to establish transitions in chemical bonds (viz., -Si-OH-Al-, OH-Na, OH-Al-), crystallinity and cation exchange capacity of these residues. Based on extensive studies, it has been demonstrated that FT-IR spectroscopy is extremely useful for 1) detection of chemical bonds in the residues, 2) evaluation of zeolites in the residues and 3) also establishing the superiority of the two-stage interaction of the fly ash with NaOH for synthesizing better fly ash zeolites (viz., Na-P1 and Hydroxysodalte) as compared to those obtained from the conventional single-stage treatment of the fly ash.

关键词： hydrothermal treatment     alkali activation     fly ash zeolites     X-ray diffraction (XRD) and Fourier transform-infrared radiation (FT-IR) spectroscopy    

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Physical and mechanical properties of municipal solid waste incineration residues with cement and coal flyash using X-ray Computed Tomography scanners

Toshifumi MUKUNOKI, Ta Thi HOAI, Daisuke FUKUSHIMA, Teppei KOMIYA, Takayuki SHIMAOKA

《结构与土木工程前沿（英文）》 2019年 第13卷 第3期   页码 640-652 doi: 10.1007/s11709-018-0502-6

摘要： A significant volume of Municipal Solid Waste incineration bottom ash and fly ash (i.e., incineration residues) are commonly disposed as landfill. Meanwhile, reclamation of landfill sites to create a new land space after their closure becomes an important goal in the current fewer and fewer land availability scenario in many narrow countries. The objective of this study is to reclaim incineration residue materials in the landfill site by using cement and coal fly ash as stabilizers aiming at performing quality check as new developed materials before future construction. Indeed, physical and mechanical properties of these new materials should be initially examined at the micro scale, which is the primary fundamental for construction at larger scale. This research examines quantitative influences of using the combination of cement and coal fly ash at different ratio on the internal structure and ability of strength enhancement of incineration residues when suffering from loading. Couple of industrial and micro-focus X-ray computed tomography (CT) scanners combined with an image analysis technique were utilized to characterize and visualize the behavior and internal structure of the incineration residues-cement-coal fly ash mixture under the series of unconfined compression test and curing period effect. Nine types of cement solidified incineration residues in term of different curing period (i.e., 7, 14, 28 days) and coal fly ash addition content (i.e., 0%, 9%, 18%) were scanned before and after unconfined compression tests. It was shown that incineration residues solidified by cement and coal fly ash showed an increase in compression strength and deformation modulus with curing time and coal fly ash content. Three-dimension computed tomography images observation and analysis confirmed that solidified incineration residues including incineration bottom and fly ash as well as cement and coal fly ash have the deliquescent materials. Then, it was studied that stabilized parts play a more important role than spatial void distribution in increment or reduction of compression strength.

关键词： mechanical property     municipal solid waste incineration residues     coal fly ash     unconfined compression test     image analysis     X-Ray Computed Tomography scanners    

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标题 作者 时间 类型 操作

Effects of sulfur on variations in the chemical speciation of heavy metals from fly ash glass

期刊论文

Service life prediction of fly ash concrete using an artificial neural network

期刊论文

Direct synthesis of carbon nanotubes on fly ash particles to produce carbon nanotubes/fly ash composites

Fangxian LI, Cheng ZHOU, Pengfei YANG, Beihan WANG, Jie HU, Jiangxiong WEI, Qijun YU

期刊论文

Effect of fly ash replacement level on the fracture behavior of concrete

Mahdi AREZOUMANDI, Jeffery S. VOLZ

期刊论文

Accelerated engineering properties of high and low volume fly ash concretes reinforced with glued steel

Vallarasu Manoharan SOUNTHARARAJAN, Dr. Anandan SIVAKUMAR

期刊论文

Effects of seeding nucleation agent on geopolymerization process of fly-ash geopolymer

Lapyote PRASITTISOPIN, Issara SEREEWATTHANAWUT

期刊论文

Porous silica synthesis out of coal fly ash with no residue generation and complete silicon separation

期刊论文

Fresh and hardened properties of high-performance fiber-reinforced concrete containing fly ash and ricehusk ash: Influence of fiber type and content

Nguyen-Trong HO; Viet Quoc DANG; Minh-Hieu NGUYEN; Chao-Lung HWANG; Trong-Phuoc HUYNH

期刊论文

The investigation of fly ash based asphalt binders using atomic force microscope

Rajan SAHA, Kyle MALLOY, Emil BAUTISTA, Konstantin SOBOLEV

期刊论文

Chloride binding and time-dependent surface chloride content models for fly ash concrete

S. MUTHULINGAM,B. N. RAO

期刊论文

Compressive strength and stability of sustainable self-consolidating concrete containing fly ash, silica

Osama Ahmed MOHAMED, Omar Fawwaz NAJM

期刊论文

Characteristics of the stabilized/solidified municipal solid wastes incineration fly ash and the leaching

Yan SHAO,Haobo HOU,Guangxing WANG,Sha WAN,Min ZHOU

期刊论文

Mercury emission and adsorption characteristics of fly ash in PC and CFB boilers

Li JIA, Baoguo FAN, Xianrong ZHENG, Xiaolei QIAO, Yuxing YAO, Rui ZHAO, Jinrong GUO, Yan JIN

期刊论文

Establishing two-stage interaction between fly ash and NaOH by X-ray and infrared analyses

Bhagwanjee JHA,Nevin KOSHY,Devendra Narain SINGH

期刊论文

Physical and mechanical properties of municipal solid waste incineration residues with cement and coal flyash using X-ray Computed Tomography scanners

Toshifumi MUKUNOKI, Ta Thi HOAI, Daisuke FUKUSHIMA, Teppei KOMIYA, Takayuki SHIMAOKA

期刊论文