• Journal of the Korea Concrete Institute
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• v.23 no.3
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• pp.311-320
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• 2011

Fly ash (FA), byproduct from power plant has been actively used as mineral admixture for concrete. However, since bottom ash (BA) is usually used for land reclaim or subbase material, more active reuse plan is needed. Pond ash (PA) obtained from reclaimed land is mixed with both FA and BA. In this study, 6 PA from different domestic power plant are prepared and 5 different replacement ratios (10%, 20%, 30%, 50%, and 70%) for fine aggregate substitutes are considered to evaluate engineering properties of PA as fine aggregate and durability performance of PA concrete. Tests for fine aggregate of PA for fineness modulus, density and absorption, soundness, chloride and toxicity content, and alkali aggregate reaction are performed. For PA concrete, durability tests for compressive strength, drying shrinkage, chloride penetration/diffusion, accelerated carbonation, and freezing/thawing are performed. Also, basic tests for fresh concrete like slump and air content are performed. Although PA has lower density and higher absorption, its potential as a replacement material for fine aggregate is promising. PA concrete shows a reasonable durability performance with higher strength with higher replacement ratio. Finally, best PA among 6 samples is selected through quantitative classification, and limitation of PA concrete application is understood based on the test results. Various tests for engineering properties of PA and PA concrete are discussed in this paper to evaluate its application to concrete structure.

• Journal of the Korean Ceramic Society
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• v.50 no.2
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• pp.134-141
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• 2013

Pond ash produced from Seochun Power Station was quantitatively characterized to manufacture geopolymers with a range of Si/Al compositional ratios. Mix consistency was kept nearly constant for comparing the compressive strengths of geopolymers. The amorphous composition of coal ash was determined using XRF and quantitative X-ray diffraction. Different mix compositions were used in order to achieve Si/Al ratios of 2.0, 2.5 and 3.0 in the geopolymer binder. Geopolymers synthesized from coal ash with a Si/Al ratio of 3.0 exhibited the highest compressive strength in this study. It was found that geopolymers activated with aluminate produced different microstructure from that of geopolymers activated with silicate. High silica in alkali activators produced the fine-grained microstructure of geopolymer gel. It was also found that high compressive strength was related to low porosity and a dense, connected microstructure. The outcome of the reported experiment indicates that quantitative formulation method made it possible to choose suitable activators for achieving targeted compositions of geopolymers and to avoid efflorescence.

• Journal of the Korean GEO-environmental Society
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• v.13 no.1
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• pp.31-36
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• 2012

Recently, industrial by-products are exponentially growing because energy consumption is increasing due to rapid industrial development and improved living standards. The purpose of this study is to determine the proper mixing ratio to meet the liner conditions(must be less than $1{\times}10^{-7}$cm/sec), using pond ash and bentonite as liner. As the result of the compaction test, depending on the increase mixing ratio of bentonite, the maximum dry unit weight was decreased but the optimum moisture content was tended to be increased at the compaction curve. As the result of the permeability test, depending on the increase mixing ratio of bentonite, the coefficient of permeability showed tendency to be decreased in the form of index and the tendency was caused by the hydration reactions filling the void of the pond ash. When the mixing ratio of bentonite was approximately over 15%, it was satisfied with the land fill liner conditions. In other words, it is necessary to consider other mixtures containing the cement or another material in the economical aspect for application of the pond ash.

• Journal of Environmental Impact Assessment
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• v.9 no.1
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• pp.1-11
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• 2000

An environmental geochemical survey of heavy metal distribution in marine surface sediments around the ocean of Samcheonpo coal-fired power plant was conducted to investigate the possibility of coal-ash leakage from ash pond and the associated heavy metal pollution in sedimental deposits due to the operation of the coal-fired power plant. The X-Ray Diffractometry (XRD) analysis showed that the main leakage point of coal-ash was limited to a single site of the first ash pond. It also appeared that the amounts of organic carbon and metal elements were positively correlated to the grain size distribution, and that Co, Cr, Cu, Fe, Ni, and Zn were bounded to organic ligands. However, the distributions of Cd, Hg, and Mn did not have any significant correlation with the sediment grain size and organic matters. In particular, the distribution of Cd appeared to be affected by the concentration of the carbonate materials in the study area.

• Journal of the Korean earth science society
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• v.28 no.1
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• pp.112-122
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• 2007

It is known that coal-derived fly ashes have the unique chemical composition and mineralogical characteristics. Since iron oxides in coal fly ash are enriched with heavy metals, the subsurface media including soils, underground water, and sea water are highly likely contaminated with heavy metals when the heavy metals are leached from fly ashes by water-fly ash interactions. The purpose of this study was to investigate how indigenous bacteria affect heavy metal leaching and mineralogy in fly ash slurry during the fly ash-seawater interactions in the ash pond located in Dangjin seashore, Korea. The average pH of ash pond seawater was 8.97 in nature. Geochemical data showed that microbial activity sharply increased after the 7th day of the 60-day course batch experiments. Compared with other samples including autoclaved and natural samples, ${SO_4}^{2-}$ was likely to decrease considerably in the fly ash slurry samples when glucose was added to stimulate the microbial activity. Geochemical data including Eh/pH, alkalinity, and major and trace elements showed that the bacteria not only immobilize metals from the ash pond by facilitating the chemical reaction with Mn, Fe, and Zn but may also be able to play an important role in sequestration of carbon dioxide by carbonate mineral precipitation.

• Resources Recycling
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• v.24 no.4
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• pp.67-75
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• 2015

The content distributions of some rare metals and rare earthe metals in coal ash (fly ash, bottom ash and pond ash) and leachate from coal-fired power plants were investigated. In case of Yttrium (Y) and Neodymium (Nd) which were strategic critical elements, their contents were ranged from about 23 ~ 75 mg/kg and it is shown they are worth to be developed for the recovery and separation method. Considering the annual amount of fly ash and bottom ash and pond ash, coal-fired power plants have great value of about 1,670 billion KRW and it is regards they are worthy as urban mines.

• Proceedings of the Korean Geotechical Society Conference
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• 1999.03a
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• pp.513-520
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• 1999

20 million tons of coal ash has been produced in Korea annually. This causes the environmental problems and the cost of land for ash pond. However the amount of coal ash for recycling is small because of the low level of recycling technology and the ignorance. As the coal ash has the significant engineering properties, it can be utilized as soft ground stabilizer, backfill materials and so forth. The purpose of this paper is to summarize some of the recycling methods of coal ash. One is structural backfill materials, the other is flowable fill. Optimal mixture ratio(fly ash : bottom ash) is determined for structural backfill materials and the model test is performed. The model test accompanied with physical tests were executed for identifying that the flowable fly ash can be used as fill materials such as trench back filling.

• Journal of the Korea Concrete Institute
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• v.23 no.5
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• pp.541-550
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• 2011

Many researches have been performed on concrete with fly ash and bottom ash. However researches on concrete with pond ash (PA) and its application to RC (Reinforced Concrete) structure are limitedly carried out. This paper presents an applicability of PA concrete in construction of real size structure. Referring to the previous study, 2 domestic PA samples with normal performance are selected and 2 replacement ratios (25% and 50%) to fine aggregate are considered for 5 PA concrete structures consisting of column, slab, and wall. In order to evaluate the property of fresh concrete, several tests including air content, slump, and setting time are performed. Using cored out samples from hardened PA concrete structure, tests for strength, resistance to carbonation and chloride penetration are carried out and compared with control samples. Additionally, tests for rebound hardness, drying shrinkage, and hydration heat are performed for PA concrete structure. The test results showed that PA concrete has reasonable strength and durability performances compared to those of normal concrete. Therefore, its potential application to RC structure is promising. The PA aggregate can be more actively used for RC structures with better quality control for content of fly ash, bottom ash, and unburned carbon.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.11 no.1
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• pp.145-151
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• 1991

The final purpose of this study is to examine the uses of coal ash, by-product from thermal power plant as a type of filling-embankment materials and the reuses of ash ponds. In this time, to investigate the dynamic properties, we made the test piece specimen with coal ashes, and obtained the damping ratio. In place(ash pond), the damping property by underground wall was investigated before and after soil improvements. The damping ratio of coal ash test piece specimen of 12% cement is the highest and that of 9% cement or chemical grout, that of 6% cement is in order. In same coal ash test piece, the damping ratio increases with decreasing the void ratio. In conclusion, it could be said that the damping ratio increases with the stiffness of materials. In the ash pond, the damping effect is the most when trench is set through the vibration wave propagation course, and when soil is improved the higher stiffness of the improved soil is, the more damping effect appeared. It is justified to obtain not only the dropping of permeability and the strength increase, but also the damping effect fairly by soil improvements.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.477-480
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• 2008

With an increase of power consumption due to industrial development, the generation of coal ash has been growing tremendously and, accordingly, environmental concern over its disposal and insufficiency in disposal sites have been raised as other issues to be considered. In order to examine the usability of coal ash as an aggregate for concrete, such fundamental information as slump, air contents, mechanical properties and durability of concrete has been secured by way of setting 10, 20 or 30 wt. % of fine aggregate alternative rate of ash and identifying its basic properties at each pond-ash contents. The results of the study indicate that slump and air content heavily depend on the site of generation, and this might greatly influence on the content of fine particles of the ash. It is also shown that its freezing and thawing resistance tends to be relatively lower than that of Plain, which requires comprehensive examination over next few years on the absorptiveness and properties of mixed water of the ash collected from each disposal site.