• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.4
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• pp.152-158
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• 2007

This is a fundamental research to utilize alkali activated cement(AAC) in concrete. The compressive strength of AAC concrete were measured for the various mixing ratios of activator/fly ash, and the mixing ratios of water glass, NaOH, and water among the activators. The mixing ratio of fine and coarse aggregates was maintained constantly. The relationships between the compressive strength and mixing ratios were analyzed to find the optimal mixing ratio of AAC concrete. As the results, the optimal mixing ratio of activator/fly ash in AAC concrete was 0.7, and that of water glass, NaOH, water among the activator was 4.0:1.0:2.5 for the maximum compressive strength.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.4
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• pp.407-413
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• 2006

Artificial aggregates made by coal fly ash that is classified as an industrial by-product was tested to oxidize hydrogen sulfide under various testing conditions. For the determination of optimum condition for converting coal fly ash to aggregates, specimens were prepared by varying ratio of fly ash, cement, water content, and foaming agent. These specimens were tested to determine specific gravity, water absorption, and compressive strength. Specimens, which were used for the removal of hydrogen sulfide, were selected based on the measured specific gravity, water absorption, and compressive strength. Tests for hydrogen sulfide removal were performed via batch and column tests. Under the testing conditions used in this study, removal rates of hydrogen sulfide were linearly proportional to amounts of coal fly ash, and further increased when water was added.

• Magazine of the Korea Concrete Institute
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• v.7 no.4
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• pp.109-118
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• 1995

The permeability of concrete is closely related to the durability and the latter may be expressed by measuring permeability of concrete. According to the results, the permeability of fly ash concrete was lower than that of OPC(PC1) concrete and decreased with increasing fly ash levels(l5%, 30% and 45%). The permeability values of concrete cured in water is significantly lower than those of concrete cured in air, but the differences were reduced with increasing fly ash level. In comparison with OPC(PC1) concrete and high fly ash concrete containing enhanced early strength cements, the latter also had a lower permeability than the former. The permeability of concrete cured in water was decreased with curing time(28 and 180 days) irrespectwe of cement types. However, the trend of results cured in air was opposite to that cured in water due to the rnicrocrackinp: of concrete. It was found that the properties of strength and permeability of concrete were related each other. However, the permeability of concrete was more dependant upon the type of binder used in concrete.

• Journal of the Korean Ceramic Society
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• v.39 no.6
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• pp.540-549
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• 2002

In this work, the hydration behaviour of portland cement pastes containing fly ash, blast-furnace slag and silica fume is investigated by Impedance Spectroscopy(IS). As fly ash or blast-furnace slag was added to portland cement, the values of R$_{t(s+1)}$ and R$_{t(s+1)}$ were decreased in the early hydration period. It showed that hydration of cement containing blending components was slower than it of the reference cement paste with the same W/C ratio. However, the cement paste containing silica fume had a large value of R$_{t(s+1)}$ and R$_{t(int)}$due to very rapid pozzolanic reactivity of silica fume in the hydration time. In OPC-fly ash system, a characteristic plateau region appeared between straight-line and semicircle. The plateau region continued to grow in range with the content of fly ash and the hydration time.

• Journal of the Korean GEO-environmental Society
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• v.4 no.3
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• pp.41-49
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• 2003

If MSW(Municipal Solid Waste) landfill is used as a foundation ground of construction site, the change of loading condition may cause a large amount of compression in MSW landfill. Therefore, the reinforcement for the loose compression nature of MSW landfill would be very important design factor to geotechnical engineers in considering the end-use of the landfill. In this study, a possible technique for stabilizing MSW landfill with use of codisposal of municipal solid waste and Fly Ash is discussed. In order to estimate the stabilization of compression characteristic of codisposed landfill, large compression test and lysimeter test were performed. According to the test results, as the proportion of Fly Ash increases, the compression might be reduced, but the permeability might be also reduced. Therefore, it is necessary to take into account the both characteristics changes in real application.

• Journal of the Society of Disaster Information
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• v.10 no.4
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• pp.566-571
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• 2014

Recently, with concentrated social and engineering interests on durability, diversified subsequent researches have been progressed. The Chloride-induced corrosion, carbonation, freeze-thaw etc, deterioration factors of concrete act to concrete not privately but complexly, Fly ash is most frequently used admixture which is using a reduction method of deterioration. And the fly ash effects on improvement of durability with enhancement of fluidity, decrease of crack with reduction of hydration heat, promotion of long-age strength and have a economic advantage which replaces cement as a binding material. But, fly ash have different qualities and occasionally reduce the durability and strength by adhesion of AE admixture with unburned carbon powder etc. In this study, the experiments will take about various replacement ratio of fly ash concrete, and will analyze, consider the results, after these will verify applicability and validity as admixture and binding material.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.3
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• pp.265-269
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• 2006

This study was to investigate the effect of acidic leachate on the landfill liner system and healing of cracks by using industrial by-products; BFS(Blast Furnace Slag) and FA(Fly Ash). From the results of pH measurement, for OPC(Ordinary Portland Cement) and DM(Dredged Mud) mixtures immersed acidic leachate, the initial pH($4.5{\sim}5.5$) was heavily increased to approximately 10 after 60 days experiment due to the production of 2 mole $OH^-$ which was occurred by hydrolysis of CaO and MgO etc.. Meanwhile, the initial pH of acidic leachate immersed DM mixtures with BFS and FA respectively was lasted for longer period as compared to the comparison. The reason was that production of low Ca C-S-H hydrates which stabilized in acidic liquid. The physical properties(compressive strength, hydraulic conductivity) of DM mixtures added BFS and FA was improved. It was concluded that the dissolution of hydrates was disturbed by high alkalinity of BFS and FA.

• Magazine of the Korea Concrete Institute
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• v.3 no.3
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• pp.101-110
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• 1991

Results of an experimental study on the manufacture, the mechanical properties and watertightness of pitch - based carbon fiber reinforced fly ash. cement composites are presented in this paper. The carbon fiber reinforced fly ash. cement composites using early strength cement silica powder and a small amount of stylene butadiene rubber latex are prepared with carbon fiber, foaming agents and mixing conditions. As a result, the mechanical and physical properties such as compressive , tensile and flexural strengths, watertightness and drying shrinkage of lightweight carbon fiber reinforced fly ash cement composites are Improved by using a samll amount of stylene butadiene rubber latex. Also, the manufacturing pnx:ess technology of carbon fiber reinforced fly ash . cement composItes is developed. The development and applications of precast products of lightweight carbon fiber remforced cement composites are expected in the near future.

• Journal of the Society of Disaster Information
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• v.10 no.2
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• pp.238-243
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• 2014

Recently environmental pollution is serious and therefore, This study aims at reviewing individual mixing ratio and engineering characteristics of concrete due to mixture and mixing using fine powder and fly ash of blast furnace slag having effect on aspects of environmental preservation and resources recycling and performance increase of the concrete, and verifying possibility of application in the field. Test results are as follows: 1)As mixing quantity of the admixture has increased, performance of the slump has been improved, 2)As mixing quantity of the admixture has increased, there is a trend of delayed ending time, 3)As mixing quantity of admixture has increased, it has showed lower strength at short time age, however, as the age has elapsed and mixing quantity has increased, strength improvement has increased and the admixture has effect on the long term age. In this study, the characteristics and critical value of concrete contained blast furnace slag and fly ash are defined, and will be examined about the field applications.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.4
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• pp.114-121
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• 2010

Portland cement production is under critical review due to high amount of CO2 gas released to the atmosphere. Attempts to increase the utilization of a by-products such as fly ash and ground granulated blast-furnace slag to partially replace the cement in concrete are gathering momentum. But most of by-products is currently dumped in landfills, thus creating a threat to the environment. Many researches on alkali-activated concrete that does not need the presence of cement as a binder have been carried out recently. However, most study deal only with alkali-activated ground granulated blast furnace slag or fly ash, as for the combined use of the both, little information is reported. In this study, we investigated the influence of mixture ratio of fly ash/ blast furnace slag tand curing condition on the flowability and compressive strength of mortar in oder to develop cementless alkali-activated concrete. In view of the results, we found out that the mixture ratio of fly ash/blast furnace slag always results to be significant factors. But the influence of curing temperature in the strength development of mortar is lower than the contribution due to other factors. At the age of 28days, the mixture 50% fly ash and 50% ground granulated blast furnace slag activated with 1:1 the mass ratio of 9M NaOH and sodium silicate, develop compressive strength of about 65 MPa under $20^{\circ}C$ curing.