• 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 Korea institute for structural maintenance and inspection
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• v.17 no.3
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• pp.108-117
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• 2013

Among the byproducts from thermal power plant using coal combustion, fly ash as mineral admixture is widely utilized in concrete manufacturing for its engineering merits. However residuals including bottom ash are usually reclaimed. This study presents an evaluation of engineering properties in cement mortar with pond ash (PA). For this work, two types of pond ash (anthracite and bituminous coal) are selected from two reclamation sites. Cement mortar specimens considering two w/c (0.385 and 0.485) ratios and three replacement ratio of sand (0%, 30%, and 60%) are prepared and their workability, mechanical, and durability performance are evaluated. Anthracite pond ash has high absorption and smooth surface so that it shows reasonable workability, strength development, and durability performance since it has dense pore structure due to smooth surface and sufficient mixing water inside. Reuse of PA is expected to be feasible since PA cement mortar has reasonable engineering performance compared with normal cement mortar.

• 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.

• 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.

• 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.

• 발명특허
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• v.30 no.10 s.352
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• pp.38-41
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• 2005

산업의 발전과 함께 산업폐기물이 늘어나고 있고 이 폐기물의 처리방법 중 가장 일반적이고 많은 사례가 매립이다. 폐기물을 매립할 때 필요한 것이 복토재인데 우리나라에서 복토재로 사용이 가능한 흙은 매립장을 건설할 때 발생되는 잔토와 건설현장에서 발생되는 흙, 하천의 준설토 등이 있다. 하지만 모든 흙을 모두 복토재로 사용할 수는 없는데, 건설현장의 잔토는 건설폐기물로 분류되어 지정매립장에 매립을 해야 하고 하천 준설토는 2차 오염의 방지를 위해 복토재로 사용할 수 없도록 법으로 금지되어 있기 때문이다. 이런 규제는 복토재용 흙을 안정적으로 확보할 수 없게 하고 수요만큼의 공급이 불가능하게 되어 불법적인 사용 가능성을 암묵적으로 인정하는 현실로 이어졌다.

• Journal of the Korean Geotechnical Society
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• v.27 no.10
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• pp.45-54
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• 2011

In this study, the consolidation characteristics are investigated on the artificial soil mixture of kaolinite, fine soils representing dredged soils and reclaimed coal ash from the ash ponds. A large sedimentation chamber was designed and manufactured to produce the artificial soil mixture with uniform stress history. In order to examine the consolidation characteristics in lateral and vertical directions, standard consolidation and Rowe Cell tests were performed. From the results of standard consolidation tests, the artificial soil mixture with coal ash showed lower compressibility and the larger consolidation coefficients enough to aid in early stabilization of the reclaimed sites compared with the kaolinite only. Also, in order to examine the consolidation characteristics when applying vertical drains, the drainage material was installed and tested in the Rowe Cell. The Rowe Cell test results show that the artificial soil mixture yields higher coefficient of consolidation. Thus, the application of artificial soil mixture on the reclaimed sites can shorten the consolidation time.

• 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.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.841-844
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• 2008

Non-refining fly ash and bottom ash, the byproducts generated from the coal-fired power stations, have usually been disposed of in onshore ash disposal sites. With an increase of power consumption due to industrial development, the generation of coal ash has been growing tremendously. Current insufficiency of disposal sites and environmental concerns over newly-built disposal sites have also led a growing need to utilize the coal ash. Accordingly, this paper compares and analyzes the fundamental properties of the coal ash collected from each disposal sites in order to increase the usability of the coal ash generated from coal-fired power stations. The results of the study indicate that coal ash shall be separately applied by the properties for each intended use as the ash greatly differs in its properties depending on the site of disposal. In particular, it is shown that the overall evaluation on the ash shall be necessary as the quality might be varied by the change of absorptance when applied as an aggregate for concrete. From the examination on the salt content, it has been observed that the ash can be applied as an aggregate for concrete only after more than 3 times of washing process.

• Journal of the Korean GEO-environmental Society
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• v.14 no.2
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• pp.5-11
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• 2013

This study introduces a densification technique of controlled low strength materials (CLSM) made with coal ashes by pump discharge pressure. Based on a small-scale laboratory test results, unit weight of CLSM around discharge pipe is greater than that of relatively some distant area from discharge pipe. It is also found that densification of CLSM depends on not only mixture rate of pond ash but also fly ash and location of discharge pipe.