• 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.

• 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.

• 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.

• Korean Journal of Materials Research
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• v.32 no.1
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• pp.23-29
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• 2022

Fly ash is a by-product of coal fired electrical power plants and used as a material for cement and concrete; particularly, imported fly ash is mainly applied for cement production. Main objectives of this article are to replace domestic fly ash with an imported source. To verify the possibility of domestic fly ash as a material for cement from the aspect of chemical composition and physical properties, we manufactured various kinds of cement, such as using only natural raw material, shale, and partial replacement with domestic and imported fly ash. When we used the domestic and imported fly ash, there were no specific problems in terms of clinker synthesis or cement manufacturing in relation to the natural material, shale. In conclusion, domestic fly ash has been confirmed as an alternative raw material for cement because 7 days and 28 days compressive strength values were better than those of reference cement using natural raw material, on top of the process issue.

• Journal of the Korean Ceramic Society
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• v.39 no.12
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• pp.1164-1170
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• 2002

The effect of fly ash addition to the kaolin block has been investigated. The addition affected the firing temperature and physical properties such as water absorption and compressive strength. The starting materials were from korea natural resources and the fly ash were from the power plant using coal as fuel, containing free carbon of 8∼9 wt%. The starting natural materials were mixed with 5 different proportions of fly ash, pressed and then sintered at 1050, 1100, 1150 and 1200${\circ}C$. With sintering temperature, water absorption decreased and compressive strength increased. When specimens were sintered at the temperature lower than 1100${\circ}C$, water absorption increased and strength decreased with fly ash content. In contrast, when sintering was done at the temperature higher than 1150${\circ}C$, water absorption increased with fly ash content similarly but strength was improved.

• Computers and Concrete
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• v.11 no.1
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• pp.39-49
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• 2013

The use of ground fly ash in concrete can increase the risk of slump loss due to the drastic surface change of the particles after the grinding treatment and the accelerated reaction compared to the untreated ash. This study is aimed at the early age hydration and time-dependent rheology changes of cement paste containing ground fly ash. An original fly ash is ground into different fineness and the hydration of cement paste containing the ground fly ash is monitored with the ultrasound propagation method. The zeta potentials of the solid particles are measured and the changes of rheological parameters of the cement pastes with time are analyzed with a rheometer. A particle packing model is used to probe packing of the solid particles. The results show that the early age hydration of the paste is strongly promoted by replacing Portland cement with fly ash up to 30 percent (by mass), causing increase of the yield stress of the paste. The viscosity of a paste containing ground fly ash is lower than that containing the untreated ash, which is explained by the denser packing of the solid particles.

• Proceedings of the Korea Concrete Institute Conference
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• 2000.04a
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• pp.153-158
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• 2000

This study was carried out in order to investigate the relationship roundness of fly ashes and fluidity of fly ash cement paste. electrostatic precipitator system in coal-fired power plant have many successive collection fields in the direction of flue gas travel. In experiment, the roundness of fly ashes collected from the same location had similar values regardless of the load or boiler, and they increased going from the 1st collection filed to third collection filed in the direction of gas movement. In considering the relation between roundness of fly ashes and fluidity of fly ash cement paste, it has a high correlation.