• Journal of the Korean Crystal Growth and Crystal Technology
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• v.27 no.5
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• pp.249-255
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• 2017

Using a magnetic separation process, pond ash generated in thermoelectric power plants was separated into magnetic materials and nonmagnetic materials in order to make it into a raw material of geopolymers and unburned carbon; screening characteristics according to the particle sizes and magnet strength levels of the pond ash were observed. Based on the results of magnetic separation into fine particle (0.15~0.84 mm) and rough particle (0.84~2.4 mm) pond ash using 3000 G magnets, the weight fraction and ignition loss of nonmagnetic materials were found to be higher than those of magnetic materials, regardless of the particle size. In the case of fine particle pond ash, when the magnet strength was increased from 3000 G to 10000 G, even those materials that were weakly magnetic were separated into magnetic materials, leading to drastic increases in the weight fraction of magnetic materials, such that the ignition loss accounted for 66.9 % (22.8 wt%) of the entire ignition loss of 32.6 wt%, despite of the low ignition loss. Based on the results of measurement of the compressive strength levels of geopolymers made of magnetic-separated rough particle pond ash, the compressive strength of geopolymers made of magnetic materials containing small amounts of unburned carbon was found to be 20 MPa.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09b
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• pp.32-37
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• 2010

Recently, the land area for many people has been limited because of industrialization and modernization in Korea. The large-scale constructions like the reclamation development projects have been progressed to resolve this problem mentioned above. Therefore, as many of the usefulconstruction materials as possible are needed to perform the large-scale construction projects. Many studies for the utilization of pond ash which has a similar characteristic of sand have been conducted and there has been often occurred many structural problems on roadbed in winter. Therefore, the characteristics of the freezing and thawing for Controlled Low-Strength Material (CLSM) using pond ash were analyzed and evaluated by unconfined compressive strength test in this study. As a result of this study, it was confirmed that new CLSM using pond ash with cement (8.2% by weight)was able to stand for the freezing and thawing behavior.

• Journal of the Korean Geotechnical Society
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• v.26 no.1
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• pp.75-83
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• 2010

Controlled low strength material (CLSM) is a flowable mixture and does not need to be compacted. It is produced by mixing portland cement, fly ash, fine aggregates, water and chemical admixtures. Sand is the most commonly used fine aggregates in the conventional CLSM, but it is getting more and more difficult to obtain sand in Korea. In this study, the characteristics of unconfined compressive strength, flow and applicability of a new CLSM that is produced by mixing of pond ash, fly ash, water, cement are examined. An unconfined compressive strength satisfies the standard unconfined compressive strength (0.5~1.0 MPa) were obtained when the mixture ratio of pond ash and fly ash is 30:70~70:30, cement ratio is 3.0~5.0%, and water content is 31~34%. The results of flow test indicate that the mixture ratio of pond ash and fly ash which satisfy the standard How value (0.2 m) is 30:70~70:30.

• Geomechanics and Engineering
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• v.12 no.1
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• pp.85-109
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• 2017

The paper presents the laboratory study of clayey soil stabilized with Pond ash (PA), Rice husk ash (RHA), cement and their combination used as stabilizers to develop and evaluate the performance of clayey soil. The effect of stabilizer types and dosage on fresh and mechanical properties is evaluated through compaction tests, unconfined compressive strength tests (UCS) and Split tensile strength tests (STS) performed on raw and stabilized soil. In addition SEM (scanning electron microscopy) and XRD (X-ray diffraction) tests were carried out on certain samples in order to study the surface morphological characteristics and hydraulic compounds, which were formed. Specimens were cured for 7, 14 and 28 days after which they were tested for unconfined compression tests and split tensile strength tests. The moisture and density curves indicate that addition of RHA and pond ash results in an increase in optimum moisture content (OMC) and decrease in maximum dry density (MDD). The replacement of clay with 40% PA, 10% RHA and 4% cement increased the strength (UCS and STS) of overall mix in comparison to the mixes where PA and RHA were used individually with cement. The improvement of 336% and 303% in UCS and STS respectively has been achieved with reference to clay only. Developed stabilized soil mixtures have shown satisfactory strength and can be used for low-cost construction to build road infrastructures.

• Journal of the Korean GEO-environmental Society
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• v.11 no.7
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• pp.51-56
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• 2010

Recently, the land area for many people has been limited because of industrialization and modernization in Korea. The large-scale constructions like the reclamation development projects have been progressed to resolve this problem mentioned above. Therefore, as many of the useful construction materials as possible are needed to perform the largescale construction projects. Many studies for the utilization of pond ash which has a similar characteristic of sand have been conducted and there has been often occurred many structural problems on roadbed in winter. Therefore, the characteristics of the freezing and thawing for Controlled Low-Strength Material(CLSM) using pond ash were analyzed and evaluated by unconfined compressive strength test and mass loss test in this study. As a result of this study, it was confirmed that new CLSM using pond ash with cement(8.2% by weight) was able to stand for the freezing and thawing behavior and was satisfied with the standard of Portland Cement Association.

• Journal of Soil and Groundwater Environment
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• v.23 no.6
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• pp.82-89
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• 2018

The objective of this study is to evaluate efficiencies of chemical suppressants for control of fugitive dust in ash pond of thermal power plant. In this study, $MgCl_2$, PAM (polyacrylamide), and PVA (poly vinyl alcohol) that are generally applied to suppression of fugitive dust generated from unpaved road, coal mining, storage piles and etc, were employed as chemical dust suppressants. The coal ash (coal combustion residuals) were sampled from the ash pond of Yeongheung power division in Incheon, South Korea. The characterization of the sample including particle size distribution, pH, $pH_{PZC}$ and pore volume as well as XRF analysis were carried out. The suppressant treated-samples were investigated with the wind tunnel experiments to estimate and compare the effect of suppressants on stabilization of the surface of coal ash samples. According to the results, the stability of suppressant-treated samples were significantly improved compared to water-treated samples. Among the three kinds of suppressants, PAM and PVA showed higher efficiencies and cost saving than $MgCl_2$.

• Land and Housing Review
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• v.14 no.2
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• pp.137-145
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• 2023

In this study, the characteristics such as flowability, bleeding rate, and strength of the CLSM (Controlled Low Strength Material) according to physical properties such as particle size distribution and particulate content of the pond ash were investigated as part of the practical development of technology for CLSM using pond ash. As a result of analyzing the properties of the collected pond ash, it was found that the density and particle size distribution characteristics were different. And that the bleeding ratio did not satisfy the standard in the case of the specimen with a large amount of fly ash and a lot of addition of mixing water. As a result of the compressive strength test, the strength development of 0.5 MPa or more for four hours was found to be satisfactory for the specimens using hemihydrate gypsum with a unit binder amount of 200 or more, and the remaining gypsum showed poor strength development. Although it was determined that landfill coal ash can be used as a CLSM material, it is necessary to identify and apply the physical and chemical characteristics of coal ash buried in the ash treatment plant of each power generation company.

• Journal of the Korean GEO-environmental Society
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• v.14 no.10
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• pp.39-47
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• 2013

Recently, there have been various domestic construction activities related to the reclamation of the dredged soils to expand the land use. However, the reclaimed grounds made of the dredged soils cause various problems due to highly compressible and low shear strength nature. Particularly, this nature induces huge problems in case of the harbor facilities and road construction on the reclaimed sites. Furthermore, in the reclamation activities, the marine dredged soils are often used instead of the well sorted sand, which induces problems of compressibilities. Therefore, in this study, the mechanical characteristics of artificial soil mixture of kaolinite representing the marine dredged soils and the pond ash. A large consolidometer is designed and manufactured to produce the artificial soil mixture. To represent various mixing ratio between the fly ash and bottom ash in the pond ash, six samples with the same stress history are made with different mixing ratio among kaolinite, bottom ash and fly ash. Isotropically consolidated and undrained compression tests are performed to investigate the shear characteristics of soil mixtures. Based on the experimental results, as the components of mixed ash increase, the friction angle increase and the cohesion values decrease. Also, the porepressure parameters at failure, Af increase with the mixing components of the pond ash. The portion of bottom ash has more impact on the shear behavior than that of fly ash.

• Journal of the Korean GEO-environmental Society
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• v.13 no.12
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• pp.75-79
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• 2012

In the recycling of industrial waste unlike household waste, the legislation and the governmental systematic support, etc. were not also established due to an anxiety of hazard or harmfulness, etc. and a preconception. So the legislation and the system should be urgently established for the recycling of industrial waste. In this study, the environmental analyzing method of industrial waste-mixed coal ash in ash pond to recycle as a construction material is suggested by considering and analyzing test process and results about environmental impact factors of mixed coal ash. It is certified that there are not environmental problems in the recycling of mixed coal ash in ash pond as a construction material, according as its classification is general waste and each corresponding item of the leaching test result are satisfied with the 'environmental safety criteria' suggested in this study. And to build database, it is necessary to survey the environmental impact on surrounding areas with time after its recycling as a construction material.

• Journal of the Korean earth science society
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• v.32 no.2
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• pp.170-179
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• 2011

Fly ashes derived from coal fired power plants have unique chemical and mineralogical characteristics. The objective of this research was to study how indigenous bacteria affected heavy metal leaching in fly ash slurry during the fly ash-seawater interactions in the ash pond located in Yeongdong seashore, Korea. The in-situ pH of ash pond seawater was 6.3-8.5. For this study, three sites of the ash pond were chosen to collect a sample of fly ash slurry. Three samples that had a mix of fly ash (0.4 L) and seawater (1.6 L) were collected at each site. First sample was autoclaved ($120^{\circ}C$, 2.5 atm), second one was inoculated with glucose to stimulate the microbial activity, and the last sample was kept in the natural condition. Compared with other samples including autoclaved and natural samples, the glucose added sample showed sharp increase in its alkalinity after 15 days, cation concentration change such as Ca, Mg, and K seemed to increase in early stage, and then decrease 15 days later in slurry solution of glucose added sample, and a possibly considerable decrease in $SO_4^{2-}$ in the fly ash slurry samples when glucose was added to stimulate the microbial activity. Geochemical data of this study is likely to be related to the activity of bacteria at the ash pond. The result may be used to understand about the characteristic of bacteria.