• Proceedings of the Korea Concrete Institute Conference
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• 2001.11a
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• pp.303-308
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• 2001

Recently, concrete structures have become larger and higher and are demanding high performance concrete with lower heat to prevent thermal cracking, far greater workability, high strength and durability, Application of low heat portland(Type IV) cement for the high performance concrete is the best solution to satisfied those requirements. Here are explained the effect on the properties of high flowing concrete using low heat portland cement by material and mixing variations. Variables for sensitivity test were selected items like finess modulus of aggregates, particle size of limestone powder, unit water, superplasticizer, viscosity agent and concrete temperature. The results of this study were be applied to slurry wall of #215 and #216 of underground LNG tank in Inchon.

• KCI Concrete Journal
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• v.13 no.1
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• pp.35-41
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• 2001

This paper investigated rheological properties of binder pastes for self-compacting high performance concrete. Six mixtures of self-compacting concrete were initially prepared and tested to estimate self-compacting property. Then, the binder pastes used in self-compacting concrete were tested for rheological properties using a rotary type rheometer. Binder pastes with different water-binder ratios arid flow values were also examined to evaluate their rheological characteristics. The binders were composed of ordinary Portland cement, fly ash, two types of pulverized blast-furnace slag, and limestone powder. The flow curves of binder pastes were obtained by a rotary type rheometer with shear rate control. Slump flow, O-funnel time, box, and L-flow teats were carried out to estimate self-compacting property of concrete. The flow curves of binder pastes for self-compacting concrete had negligible yield stresses and showed an approximately linear behavior at higher shear rates beyond a certain limit. Test results also indicated that the binders incorporating fly ash are more appropriate than the other types of binders in quality control of self-compacting concrete.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2017.05a
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• pp.171-172
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• 2017

In order to meet the high performance of the concrete, the viscosity increases with water binder ratio and amount of powder. because of these problems, we use high performance water reducing agent and low viscosity water reducing agent, but side effects may occur when using large amount of water reducing agent. Therefore, in this research, in order to increase the viscosity, I would like to analyze the change in viscosity and flow characteristics of paste by utilizing fly ash and lung limestone which are generally thrown away without using high performance water reducing agent.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2021.11a
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• pp.109-110
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• 2021

An attempt has been made on a constructive approach to evaluate the performance of snail shell ash (SSA) for its corrosion performance under marine environments. Corrosion performance of steel rebar in chloride contaminated SSA with (0% to 50%) replacement levels of cement extract medium was examined through electrochemical and weight loss techniques. Initially, snail shell powder (SSP) is made by pulverizing and subsequently SSA is by thermal decomposition methods. A critical level of 20 % SSA improved both corrosion resistance properties of cement extracts. SSA is a suitable replacement material for natural limestone in cement productions.

• Economic and Environmental Geology
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• v.41 no.1
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• pp.57-62
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• 2008

The application of constructed subsurface-flow wetlands for treatment of wastewater from abandoned mines is being increased. Crushed limestone, oak chips, and mushroom composites are often employed in a bulk form, as the substrates in the bed media. Efficiency of the subsurface-flow treatment system drops with time as the hydraulic conductivity of the wetland soil decreases significantly, presumably due to chemical reactions with the wastewater. The purpose of this study is to investigate the applicability of immobilized beads carrying sulfate reducing bacteria for acid mine drainage treatment system. The ingredients of immobilized beads are organic materials such as mushroom composite and oak chips, limestone powder for a pH buffer, mixed with a modified Coleville Synthetic Brine. It was found that immobilized beads are more efficient than the bulk form for pH recovery, sulfate and heavy metal removal.

• Journal of the Korean Recycled Construction Resources Institute
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• v.5 no.4
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• pp.106-113
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• 2010

We were tried to draw a conclusions related to additive amount of gypsum in blast furnace slag in the study. In the result, fluidity of concrete decreased with an increase of gypsum and was not satisfied with KS standard in the cases of natural gypsum and limestone sludge more than 2.6% addition. Early compressive strength of concrete containing desulfurized gypsum, fluosilicic acid gypsum and phosphoric acid gypsum were improved respectively but calcined lime sludge and lime powder were not influenced on strength. If available, additive gypsum should be managed less than 2.0% owing to low fluidity. In low temperature, fluosilicic acid gypsum was to advantages on the fluidity while desulfurized gypsum was in high temperature. There also are conclusions that additive gypsum was to be 2.6% in winter and in summer; it's to be fewer than 2.6%.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.12
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• pp.804-815
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• 2019

Due to the depletion and environmental problems of fossil fuel, biomass has arisen as an alternative energy source. Biomass is a renewable and carbon-neutral source. However, it is moister and has lower energy density. Therefore, biomass needs thermal chemical conversion processes like gasification, and it does not only produce a flammable gas, called 'syngas', which consists of CO, H2, and CH4, but also some unwanted byproducts such as tars and some particulates. These contaminants are condensed and foul in pipelines, combustion chamber and turbine, causing a deterioration in efficiency. Thus this work attempted to find a method to remove tars and particles from syngas with a filter which adopts a pre-coating technology for preventing blockage of the filter medium. Hydrated limestone powder and activated carbon(wood char) powder were used as the pre-coat materials. The removal efficiency of the tars was 86 % and 80 % with activated carbon(wood char) coating and hydrated limestone coating, respectively.

• Economic and Environmental Geology
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• v.15 no.4
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• pp.205-219
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• 1982

The Eosangcheon manganese ore deposits occur as supergene weathering deposits along quartz porphyry dikes developed in the Ordovician Heungweolri dolomite and Samtaesan limestone formations. The manganese ores are composed of manganese oxide minerals and associated other minerals. Rancieite and todorokite are abundantly found, and birnessite, nsutite, pyrolusite and chalcophanite are found in minor quantities. Associated other minerals are calcite, gypsum, goethite, lepidocrosite, quartz, and sericite. Microscopic, chemical, X-ray powder diffraction, infrared absorption spectroscopic and differential thermal analyses have been made for manganese oxide minerals and associated other minerals. The relationship of birnessite and rancieite was studied by means of X-ray powder diffraction and infrared absorption spectroscopic analyses. It is assumed that these minerals are closely related to each other in crystal structure, but separate species. The manganese oxide minerals were formed mainly by replacement, precipitation from solution, and recrystallization in the supergene weathering environment. The trend of formation of manganese oxide minerals is: (Rhodochrosite)-(todorokite)-(birnessite, rancieite)-(nsutite, pyrolusite, chalcophanite).

• Journal of the Korean Recycled Construction Resources Institute
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• v.9 no.4
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• pp.545-552
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• 2021

In this study, strength and durability evaluations are performed on vibrated-rolled method mortar mixtures containing desulfurized gypsum and ferronickel slag powder. Desulfurized gypsum and ferronickel slag fine powders were substituted for 25% limestone fine powders u sed in the manu factu re of VR tu bes, and mortar specimens were prepared u sing vibrated-rolled method. Accordingly, flexural and compressive strengths were performed to evaluate the strength, and chlorine ion penetration resistance and sulfuric acid resistance tests were performed to evaluate durability. Flexural and compressive strength were improved in the range 20 to 60% of desu lfu rized gypsu m among admixtu res, and the amou nt of passing charge decreased in the choride ion penetration resistance test in the range of 20 to 80% of desulfurized gypsum. As for the resistance to su lfu ric acid, when the proportion of desu lfu rized in the admixtu re was 40%, the strength and weight change rate according to the immersion period was reduced. Appropriate use of desulfurized gypsum and ferronickel slag powder is expected to improve performance in terms of strength and durability.

• Land and Housing Review
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• v.14 no.4
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• pp.121-129
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• 2023

In this study, we attempted to reduce CO₂ generated during manufacturing by replacing limestone (CaCO₃), a carbonate mineral used to produce cement clinker, with a decarbonated raw material to which CO₂ is not bound. The raw material for decarbonization was cement paste attached to waste concrete, among various industrial by-products. Waste concrete has cement paste adhered to the aggregate, which cannot be separated efficiently by general crushing and grinding methods. Peeling and grinding methods effectively remove only the cement paste without damaging the original aggregate. The abrasion time, steel ball type, and steel ball ratio were selected as effective factors for Abrasion. An optimal abrasion experiment was conducted to produce waste concrete fine powder containing decarbonated CaO as a cement clinker raw material through an experimental design method. The experiment revealed that the optimal conditions for producing waste concrete fine powder were an abrasion time of 7 minutes, a steel ball size for pulverization of 8 mm, and a steel ball ratio for pulverization of 0.6.