Papers by Keyword: Fly Ash (FA)

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Authors: Bei Yue Ma, Ying Li, Li Bing Xu, Yu Chun Zhai
Abstract: β-Sialon powder was synthesized by in-situ carbothermal reduction-nitridation process, with fly ash and carbon black as raw materials. The influence of raw materials composition on synthesis process was investigated, and the phase composition and microstructure of the synthesized products were characterized by X-ray diffraction and scanning electronic microscope. The carbothermal reduction-nitridation reaction process was also discussed. It was found that increasing carbon content in a sample could promote the decomposition of mullite in fly ash and the formation of β-Sialon. The β-Sialon could be synthesized at 1550°C for 6h by heating the sample with the mass ratio of fly ash to carbon black of 100:56. The β-Sialon as-received in this study existed as granular with an average particle size of about 2μm. The carbothermal reduction-nitridation reaction process consisted of the nitridation processes of mullite, SiO2 and Al2O3 in fly ash as well as the conversion process of X-Sialon to β-Sialon.
Authors: Yi Miao Nie, Mao Hui Xia, Fu Sheng Niu, Shu Xian Liu
Abstract: Mineral polymer is a new category of inorganic non-mental materials, which was manufactured from fly ash in this paper. Changes of fly ash in the polymerization can be described as: (1) Q4(0Al) is the main form of Si element in fly ash, with 67.5%content.During the solidification of mineral polymer, the content of Q4(0Al) decrease from 38.7%(3d) to 28.2%(7d) and 26%(14d), then increased to 37.8% in 28 d product; (2) the intensity of Q2(0Al) and Q3(1Al) decrease at first stage, then increase finally during the solidification of mineral polymer; (3) content of Q4(2Al)increase from 14.6%(3d), 39.2%(7d), 40.6% (14d) and decreased to 23.1% in product curing for 28 d product;(4)octahedral aluminum were the main form of Al element in fly ash, which decreased during the polymerization, simultaneously, tetrahedral aluminum increased. The experimental results provided a good basis for understanding the reactive mechanism of polymerization.
Authors: Lin Xu, Chong Fang
Abstract: In order to solve the problems of one-sidedness of current researches in classification of fly ash, degree of fineness, vitreous body, ignition loss, K2O, SO3 and CaO are chosen as the index properties to analyze projection pursuit classification method after analyzing chemical constituents and physical properties that influence the quality of fly ash. Targeting on the activity characteristics, the thesis establishes a projection pursuit cluster analysis model and makes a program on the basis of MATLAB. Population migration algorithm is adopted to seek an optimal projection direction. Fly ash is classified in accordance with property index value of the projection. Researches have proved that the model overcomes the shortcomings of traditional classification methods and reflects the quality and performance of fly ash in a comprehensive way. The evaluation is simple with accurate results and provides a scientific basis for the comprehensive utilization of fly ash.
Authors: Attanadol Prapajaraswong, Seksak Asavavisithchai
Abstract: Al foam is an advanced engineering material with many outstanding properties, such as very low density, high specific strength and stiffness, and large energy absorption. In the present study, pure Al foams were mixed with either cenosphere or precipitator fly ash particles of various contents. Fly ash particles are used in Al foams as reinforcement and stabilising materials which enable the foams with large expansion. It is found that Al foams with precipitator fly ash particles of various contents exhibited larger expansions than the foams with cenosphere fly ash particles. The quantitative analysis also revealed that more stable foam structure was obtained in Al foams with precipitator fly ash addition.
Authors: Ye Zhang, Peng Xuan Duan, Bao Sheng Jia, Lei Li
Abstract: In this paper, compared with common fly ash, the low-silicon coal gangue fly ash is used to produce fly ash autoclaved aerated concrete. The influences of water binder ratio, coal gangue fly ash content, calcareous content and conditioning agents on the compressive strength of the autoclaved aerated concrete are investigated. The results indicate the coal gangue fly ash has different properties from the common fly ash such as its granule appearance and the activity as AAC siliceous raw material. It is noting that the coal gangue fly ash can also be used to prepare AAC blocks by optimizing the raw material formulation and procedure and its B05 product can reach the China top industrial standard.
Authors: Yuan Li, Lei Jia, Xu Li Liang
Abstract: In this paper, the role of fly ash and slag powder on the concrete are introduced. Through the experiments that mixing up fly ash , slag powder or two kinds of mineral admixtures in the concrete, the characteristics of property of concrete at different times are learned. The results show that the property of concrete are better when two kinds of mixtures are used than mixing one of them, and the most appropriate proportion of mixing is 30%~40%.
Authors: Elza Bontempi, Annalisa Zacco, Laura Borgese, Alessandra Gianoncelli, Rosario Ardesi, Laura E. Depero
Abstract: In the last years several projects have been developed for treatment of fly ash with the aim of their reuse. A final target of these researches is to evaluate the real performance of the new materials obtained by the treatment and the actual and, if the case, potential markets for the foreseen products. Indeed, the use of a recycled inert would reduce the consumption of natural resources and this is one of the main environmental EU target. Examples are clinkering, road asphaltation and some construction work where specific performances are requested. Moreover, the reuse of inerted fly ash will obtain a reduction of carbon dioxide produced by the necessary treatments of primary materials, as limestone in concrete production. At the University of Brescia (Italy) a new process, based on colloidal silica medium, has been developed to inertise fly ashes, containing heavy metals. This approach appears to be quite promising for industrial application in view of the easiness that can be foreseen in applying it to existing plants treating industrial fly ash. The obtained inert product is a powder, that can be employed as a filler in several application. In this work we present first results about characterization of this new powder material, that can be applied as a filler.
Authors: An Ran Guo, Jia Chen Liu, Yi Bing Sun, Wen Jun Lian, Lu Yang
Abstract: A new technique of flyash utilization was presented and high-purity silica was prepared by alkali leaching. The flyash was added into sodium hydroxide solution, and then the suspension was heated to 115 °C for 30 min. After filtrated, the filtrate was collected and carbon dioxide was imported into the solution. Finally, the silica would precipitate from the solution. The silica was characterized by scanning electron microscopy, X-ray diffraction and X-ray fluorescence spectrometer. The high-purity silica prepared from flyash was qualified for the rubber reinforcing agent used in shoemaking.
Authors: Mei Xun Peng, Zheng Hong Wang, Shao Hua Shen
Abstract: Class F fly ash-based geopolymers formed by pressure were prepared, and the preparation factors effecting on properties especially mechanical strength were discussed and optimized. The geopolymer specimens show excellent integrated properties such as mechanical strength, acid-resistance and water absorption and can be potentially applied to acid-resisting bricks except for acid-resistance left to be improved. The elevated curing temperature and the prolonged curing time are both beneficial to develop the mechanical strength as well as the moderately increased forming pressure and quartz sand/fly ash ratio. Being pretreated at elevated temperature for proper time before press forming improves the mechanical strength and reduces the water absorption greatly.
Authors: Bei Yue Ma, Bo Li, Yu Shi Ding, Chen Yan, Ying Li, Yao Shu
Abstract: The latest development on preparation of SiC-AlN, SiC-mullite and β-Sialon materials using fly ash via in-situ carbothermal reduction process was reviewed. The synthesis mechanisms of SiC based materials and β-Sialon were also discussed.
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