• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.11a
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• pp.95-96
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• 2012

This study makes with the environment-friendly artificial stone which doesn't use the cement and natural aggregate and increases the blast furnace slag that is the eco-friendly material that is the industrial byproduct, fly ash, and availability of the red mud and applies the coares aggregate substitute material as the cleistothecium. The experimental plan according to it indicated the compressive strength and flexural strength which is the most excellent in the mixied ratio 40% of the result degree of closeness magnetism of experimenting with the optimal mix obtained through the preceding stude.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.34 no.2
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• pp.66-72
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• 2024

In this study, the applicability of CCMs (Carbondioxide conversion capture materials) manufactured by reacting carbon dioxide gas with DG (Desulfurization gypsum) as a cement substitute for secondary concrete products were evaluated and the basic physical properties of CCMs-mixed mortar and concrete specimens were measured to derive the optimal mixing ratio. The main chemical oxides of CCMs were CaO and SO₃, and the main crystalline phases were CaSO₄·2H₂O, Ca(OH)₂, CaCO₃, and CaSO₄. In addition, by the results of particle size analysis and heavy metal measurement, the applicability of CCMs as a cement substitute for secondary concrete products was confirmed. As a result of measuring the strength behavior using mortar and concrete specimens with CCMs, the compressive and flexural strength decreased as the mix ratio of CCMs increased, but requirements by the standards for interlocking blocks and retaining wall blocks, which are target products in this study, were satisfied up to the optimal mixing ratio of 10 wt.% substitution. Therefore, its applicability as a cement substitute for secondary concrete products was confirmed.

• Land and Housing Review
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• v.15 no.1
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• pp.147-156
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• 2024

This study aims to reduce CO₂ generated during the manufacturing process by using limestone (CaCO₃), a carbonate mineral used in the production of cement clinker, as a decarbonated raw material that does not contain CO₂. Among various industrial by-products, we attempted to use cement paste attached to waste concrete. In general, limestone for cement must have a CaCO₃ content of at least 80% (CaO, 44% or more) to ensure the quality of cement clinker. However, the CaO content of waste concrete fine powder is about 20% on average, so in order to use it as a cement clinker raw material, the CaO content must be increased to more than 35%. Therefore, by using the difference in hardness of the mineral composition of waste concrete fine powder to selectively crush CaO type minerals with relatively low hardness, classify and sieve, the CaO content can be increased by more than 35%. Accordingly, in this study, we experimentally and statistically reviewed and analyzed the optimal conditions for efficiently separating CaO and SiO₂ and other components by selectively pulverizing minerals containing relatively low CaO through a grinding process. As a result of the optimal grinding conditions experiment, it was found that the optimal conditions were a grinding time of less than 5 minutes, a type of material to be crushed of 30 mm, and an amount of material to be crushed of 1.0 or more. However, it is judged that it is necessary to review pulverized materials of mixed particle sizes rather than pulverized products of single particle size.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.04a
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• pp.689-692
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• 2008

The purpose of this study was to analyze mechanical properties through an experiment of concrete that reinforced PET fiber, blast furnace slag and Hwangtoh. As admixture that is substitute material of cement for environmental concrete development In order to measure compressive strength, the experiment has executed to concrete, Hwangtoh concrete and a mixture specimen of Hwangtoh and PET reinforcement fiber. Also, creep and drying shrinkage experiment have executed to analyze long-term quality of specimens. Test results, compressive strength by age was not much of difference as a substitute, however, compressive strength of HTC specimen was the strongest of the three specimens. In the case of creep and drying shrinkage, long-term quality of HTC specimen was distinguished.

• Resources Recycling
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• v.16 no.1 s.75
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• pp.44-53
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• 2007

The Jeonju-Il mine tailings contain large quantities of $SiO_2\;and\;Al_2O_3$ and lesser quantities of metallic components. In this study, we studied about the possibility of using mine tailings as a raw material in various industries. it was found that the sintered mine tailings had a good quality in every respect such as chromaticity, firing shrinkage and water absorption etc. Therefore if can substitute clay mineral in the ceramic industry. Also it can substitute about 2.94% of the raw materials of ordinary portland cement. We can use the coarse tailing as the fine aggregate for the ready-mixed mortar; and the fine tailing, as the filler for the bituminous paving mixture; because both products were not only suitable for Korea industrial standard in quality, but also environmentally harmless.

• Land and Housing Review
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• v.3 no.3
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• pp.287-297
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• 2012

To develop 80MPa-high strength concrete with ternary cement used in OPC, blast-furnance slag, and fly ash, mixing ratio of blast-furnace slag and fly ash was evaluated in material characteristics before and after hardening of the high strength concrete. According to the evaluated results of material characteristics before and after hardening of the high strength concrete, the flowability and long-term compressive strength increase up to 30% mixing ratio of blast-furnace slag and fly ash. Also, it is superior to characteristics of length change and neutralization due to the use of mineral admixture when compared in test sample mixed with OPC. The evaluated results show that material characteristics of the high strength concrete was the most outstanding performance at blast-furnace slag of 25% and fly ash of 15%. The result of this study will be useful for the development of high strength concrete as a substitute of costly silica fume in the near future.

• Journal of the Korea Institute of Building Construction
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• v.7 no.4
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• pp.101-108
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• 2007

Furnace slag powder used currently in Korea needs to add special functions in response to the increase of large-scale projects. In addition, it is advantageous in that it has a lower hydration heat emission rate than ordinary Portland cement and improves properties such as the inhibition of alkali aggregate reaction, watertightness, salt proofness, seawater resistance and chemical resistance. However, furnace slag powder is not self -hardening, and requires activators such as alkali for hydration. Accordingly, if recycled fine aggregate, from which calcium hydroxide is generated, and furnace slag, which requires alkali stimulation, are used together they play mutually complementary roles, so we expect to use the mixture as a resource-recycling construction material. Thus the present study purposed to examine the properties and characteristics of furnace slag powder and recycled aggregate, to manufacture recycled fine aggregate concrete using furnace slag and analyze its performance based on the results of an experiment, to provide materials on concrete using furnace slag as a cement additive and recycled fine aggregate as a substitute of aggregate, and ultimately to provide basic materials on the manufacturing of resource-recycled construction materials using binder and fine aggregate as recycled resources.

• Magazine of the Korean Society of Agricultural Engineers
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• v.44 no.2
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• pp.107-116
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• 2002

The amount used of aggregates for concrete is increasing rapidly since the mid-1980s in Korea. The natural gravels from river are already displaced with crushed stone, and use of crushed sand as a substitute of natural river sands, also, is getting increased day by day. This paper is presented fur analysis on mechanical properties of high strength concrete using fly ash and crushed sand. The material functions in mixing design of concretes are various water-cement ratios(w/c) such as 0.25, 0.40, 0.55 and different replacement ratio of crushed sand to natural sands such as 0%, 20%, 40%, 60%. As a results, it has been shown that compressive strengths of concretes with W/C lower than 0.40 and 0.25 are higher than 400 kgf/$\textrm{cm}^2$ and 600 kgf/$\textrm{cm}^2$ respectively. It is also concluded that the results of rapid chloride permeability tests of concrete are evaluated to negligible. The conclusions of this study is that it is possible to use fly ash and crushed sand fur high strength concrete.

• Journal of the Korean Recycled Construction Resources Institute
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• v.10 no.3
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• pp.204-210
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• 2022

Cement is pointed out as the main cause of carbon dioxide emission in the construction industry. Many researchs are underway to use blast furnace slag, an industrial by-product, as a substitute for cement to reduce carbon dioxide emitted during the manufacturing the cement. When blast furnace slag is used as a substitute for cement, it has advantages such as long-term strength and chemical resistance improvement. However, blast furnace slag has a problem that makes initial strength low. This is due to the impermeable film on the surface created during the production of blast furnace slag. The created film is known to be destroyed in an alkaline environment, and based on this, previous studies have suggested a solution using various alkali activators. But, alkali activator is dangerous product since it is a strong alkaline material. And it has the disadvantage in price competitiveness. In this study, an experiment was conducted to improve the initial hydration reactivity of the blast furnace slag to secure the initial strength of the mortar substituted with the blast furnace slag and to check whether the carbonation resistance was increased. As a result of the experiment, it was confirmed that the mortar using alkaline water showed higher strength than the mortar using tap water, and there were more hydration products generated inside. In addition, it was confirmed that the mortar using alkaline water as a compounding water had high carbonation resistance.

• Journal of the Korea Institute of Building Construction
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• v.17 no.3
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• pp.227-234
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• 2017

This research analyzes the properties of mortar following the rise in water-cement ratio and applicability as an eco-friendly construction supply by using the mudflats of a dredged arena as a substitute for aggregate. The results of a experiment of the flow showed that the flow value decreases as the amount of mudflats increases. A test for chloride content showed that the chloride content increases with the amount of mudflats. In the compression of specimen mixed with mudflat and the testing of tensile strength, the strength weakened as the addition ratio of mudflats rose. However, with 14-day strength as the standard, most specimen showed more strength than the plain, and 14-day strength was higher than 28-day strength. It appears to be experimental error in the mixing process from the viscosity and cohesion of mudflats, and it is considered that there will be a need for an experiment on mixing methods of mudflats in the future. The compressive strength of this research was the strongest with 70% in water-cement ratio, and the tensile strength was strongest with 80% in water-cement ratio. In the evaluation of surface analysis, 70% water-cement ratio, which is finest in strength, mixing, and compactness, was selected to analyze the roughness of the surface, and the results showed that the surface became smoother as the addition ratio of mudflats increases. In conclusion, it appears that 70% water-cement ratio is the optimal mixing ratio for mortar and 10 to 30% addition ratio of mudflats the optimal ratio. It also appears that the application of interior finishing material like bricks and tiles and interior plastering material using the mudflats are possible.