• Journal of the Korean Ceramic Society
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• v.39 no.2
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• pp.135-144
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• 2002

Fabrication of high strength structural concrete was investigated by using a mechanochemically Surface Treated Fly Ash(MSTFA) induced by mechanochemical processing through ball-milling of (90 wt% As Recevied Fly Ash(ARFA) + 10wt% cement) mixture, which was compared to the specimen fabricated by using As Received Fly Ash(ARFA) in terms with compressive strength and microstructures. The compressive strength of concrete specimen fabricated by using MSTFA represented 10-20% and 2-7% higher value than that for the case of using ARFA and BPFA in each cases. Increased compressive strength as above mentioned is considered to be caused by mutually increased affinity generated between cement and fly ash during mechanochemical processing.

• Resources Recycling
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• v.13 no.2
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• pp.16-23
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• 2004

To increase the recycling rate of anthracite fly ash, the properties of anthracite fly ash were compared to that of bituminous fly ash. Especially, the high temperature properties of the fly ash are investigated by using thermal analysis, high temperature microscope and X-ray diffraction analysis for utilizing anthracite fly ash to prepare the calcinated bricks. The average ratio of $A1_2$$O_3$/$SiO_2$ for anthracite is 0.62 and the ratio for bituminous is 0.34. The content of $SiO_2$ in anthracite fly ash was higher than that of bituminous fly ash. The $A1_2$$O_3$ of anthracite fly ash reacted with the $A1_2$$O_3$ in the fly ash and formed new mullite crystal at over $1000^{\circ}C$, so anthracite fly ash showed high fire resistance. And, the fly ash mixtures having kaolin were prepared, and then extruded in vacuum to evaluate the extruding property of anthracite fly ash mixture. The extruding velocity was decrease with increasing the addition amount of fly ash in the mixture, and the maximum addition amount of fly ash that could be extruded was 60 wt%.

• Resources Recycling
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• v.19 no.2
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• pp.10-18
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• 2010

This research investigates the feasibility of ceramic specimens made from Primary clay and Red Hwangto with MSWI fly ash. Specimens preduced by mix-design maximum 20 wt% MSWI fly ash were analysed by SEM, UTM, ICP, etc. As a result of measurement,$P_{10}$ specimen was improved on bending strength and $R_5$ specimen was improved on compressive and bending strength. Also amount of extracted heavy metal was suitable for regulatory limits. This indicates that MSWI fly ash is indeed suitable for the partial replacement of ceramic materials in bricks.

• Computers and Concrete
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• v.25 no.1
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• pp.83-94
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• 2020

The use of fly ash in modern-day concrete technology aiming sustainable constructions is on rapid rise. Fly ash, a spinoff from coal calcined thermal power plants with pozzolanic properties is used for cement replacement in concrete. Fly ash concrete is cost effective, which modifies and improves the fresh and hardened properties of concrete and additionally addresses the disposal and storage issues of fly ash. Soft computing techniques have gained attention in the civil engineering field which addresses the drawbacks of classical experimental and computational methods of determining the concrete compressive strength with varying percentages of fly ash. In this study, models based on soft computing techniques employed for the prediction of the compressive strengths of fly ash concrete are collected from literature. They are classified in a categorical way of concrete strengths such as control concrete, high strength concrete, high performance concrete, self-compacting concrete, and other concretes pertaining to the soft computing techniques usage. The performance of models in terms of statistical measures such as mean square error, root mean square error, coefficient of correlation, etc. has shown that soft computing techniques have potential applications for predicting the fly ash concrete compressive strengths.

• International Journal of Concrete Structures and Materials
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• v.8 no.4
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• pp.315-326
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• 2014

This study evaluates the dosages of Class F fly ash, lithium nitrate and their combinations to suppress the excessive expansion caused by alkali-silica reactivity (ASR). In order to serve the proposed objective, the mortar bar specimens were prepared from (1) four dosages of Class F fly ash, such as 15, 20, 25 and 30 % as a partial replacement of Portland cement, (2) up to six dosages of lithium nitrate, such as lithium-to-alkali molar ratios of 0.59, 0.74, 0.89, 1.04, 1.19 and 1.33, and (3) the combination of lithium salt (lithium-to-alkali molar ratio of 0.74) and two dosages of Class F fly ash (15 and 20 % as a partial replacement of Portland cement). Percent contribution to ASR-induced expansion due to the fly ash or lithium content, test duration and their interaction was also evaluated. The results showed that the ASR-induced expansion decreased with an increase in the admixtures in the mortar bar. However, the specimens made with the both Class F fly ash and lithium salt produced more effective mitigation approach when compared to those prepared with fly ash or lithium salt alone. The ASR-induced expansions of fly ash or lithium bearing mortar bars by the proposed models generated a good correlation with those obtained by the experimental procedures.

• Proceedings of the Korea Society for Energy Engineering kosee Conference
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• 1996.04a
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• pp.88-96
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• 1996

The characteristic analysis of fly ash generated from a fired power plant using bunker-C oil has been investigated. Ash size distribution by an optical microscopy with image processing technique, morphological shape by a scanning electron microscope(SEM) and microscope, chemical composition by the inductively coupled plasma emission spectrometry(ICP), and resistivity measurement as a function of temperature and moisture content by the resistivity meter are performed. A study of physical, chemical and electrical characteristics of bunker-C fly ash plays an important role of improving the performance of an electrostatic precipitator and protecting air pollution. The samples of bunker-C fly ash for analysis were collected from the electrostatic precipitator hopper of Ulsan Power Plant Unit 1 and Pusan Power Plant Unit 1. Mass median diameter(MMD) of bunker-C fly ash was measured 12.7${\mu}{\textrm}{m}$, while MMD of fly ash generated from the mixture of bunker-C oil(40%) and domestic anthracitic coal(60%) was 25.7${\mu}{\textrm}{m}$. The morphological structure of bunker-C fly ash consisted of fine particles of non-spherical shape. The primary chemical components of bunker-C fly ash were composed of SiO2(2.36%), Al2O3(4.91%), Fe2O3(14.33%) and C(11.84%). Resistivity of bunker-C fly ash was found to be increased with increasing temperature at the range of 100~15$0^{\circ}C$ and was measured 103~104 ohm-cm.

• Resources Recycling
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• v.12 no.2
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• pp.45-53
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• 2003

In 2001, Korea produced a total of 4.91 million metric tons of fly ash, approximately 63.3% of which was recycled. Almost all of the recycled fly ash are used in concrete mixtures and cement industry. Therefore, in order to develop a new usage to increase the utilization of the fly ash, conductive induction was used in this research rather than triboelectrostatic. By applying conductive induction, we could verify the possibility of obtaining high purity fly ash below 1%LOI and high carbon fly ash over 70%LOI from raw fly ash. In this test, the potential difference between the two electrodes was conducted by changing the range of 8 to 16 kV.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.05a
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• pp.31-32
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• 2013

ThThe purpose of this study is to investigate the compressive strength properties of fly ash using water eluted from recycled coarse aggregate. When fly ash come into contact with water, they have not a autonomously chemical reaction. But fly ash is a pozzolan reaction when fly ash come into contact with water and calcium hydroxide(Ca(OH)2) in alkaline environment. For that reason, if water eluted from recycled coarse aggregate use mixture water, fly ash is expected to reaction of pozzolan reaction property in early stage. According to the experimentation result, ICP-MS analysis showed water eluted from recycled coarse aggregate has a high alkali-ash value of pH of 12 and over. And mixing ratio 30% fly ash mortar using water eluted from recycled coarse aggregate showed a similar strength of plain mortar due to the pozzolan reaction. Also, poor strength in initial age, disadvantage of mortar using fly ash, can be improved as hydration in early age is expedited due to calcium hydroxide(Ca(OH)₂) and unhydrated cement component eluted from recycled aggregate mortar.

• Journal of the Korean Ceramic Society
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• v.33 no.7
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• pp.771-778
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• 1996

Utilization of fly ash by-produced from coal fired power plants and classified as general waste became very important problem to solve in the environmental protection and recycling of waste materials. The possibility of large scale substitution of fly ash as a raw material for bricks and wet tiles was highly expected because the chemical compositions of fly ash were mostly Al2O3 and SiO2 and the properties of it were very similar with clay. Accordingly in order to investigate the substitutional limit these specimens were substituted from 0 to 100 wt% fly ash by 20wt% increment for clay. Fly ash-clay bodies were fired at 1200, 1250 and 130$0^{\circ}C$ and then their properties were measured, It was found that these specimens sintered at 125$0^{\circ}C$ had a good bending strength. Especially when these sintered bodies were added to 20, 40 and 60 wt% fly ash the bending strength of those were 201 , 205 and 191kg.cm2 respectively with the water absorption below 1%, This showed that fly ash could be substituted ab 60 wt% in this experiment.

• 연구논문집
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• s.31
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• pp.5-14
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• 2001

These days, interest in the leaching of hazardous heavy metals to consist of incinerator fly ash is increasing, because the heavy metals that leach from the incinerator fly ash pollute the soil and ground water. Therefore this study was undertaken to crystallize the fly ash and prevent the leaching of hazardous heavy metals from fly ash. The concentrations and the leaching concentration of hazardous heavy metals(Cd, Cr, Hg, Pb, Zn) in the law incinerator fly ash have been measured. The fly ash was melted with two kinds of flux($Na_2CO_3, CaCO_3$) and its add quantity(0, 1, 2, 3 wt%). The crystal structure of melting materials was analyzed by SEM(Scaning Electron Microscope) and X-RD(X-Ray Diffractometer). The leaching test of melting materials was undertaken. And the relation between crystallization of melting materials and flux and leaching concentration. These experiments indicate that the concentration and leaching concentration of heavy metals in incinerator fly ash was much higher than the regulatory standard for leachates in Korea and U.S.A and average concentration of heavy metals in soil. And the crystal structure was better.