• Proceedings of the Korea Concrete Institute Conference
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• 2003.05a
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• pp.223-228
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• 2003

Recently, owing to the deterioration of reconstruction and the construction, much of the construction waste is discharged in our construction field, and the amount of construction waste is rapidly increased. These waste are raised to financial and environmental problems, so the method of reusing waste concretes has been studied and carried out many direction. Especially being want of resources, if waste concrete could be recycled as aggregates for concrete, it will contribute to solve the exhaustion of natural aggregate, in terms of saving resources and protecting environment. This study is that the mechanical properties of concrete with recycled coarse aggregate were investigated for types of mineral admixture and the substitution of recycled coarse aggregate. The result of this study, in case of using mineral admixture, the property of fresh concrete was rised. And the property of harden concrete for the substitution ratio of recycled coarse aggregate was decreased. But the property of concrete with mineral admixture was better than that of concrete used only cement.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.05a
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• pp.101-102
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• 2012

A policy for recycling waste concrete has been extensively studied, but it is still lacking to recycle and reuse as a cementitious powder, and the property has big different depending on the aggregate rates. In this study, the amount of cement powder according to the internal properties of the aggregate were mixed. From as a result, Concrete Powder to play inside the aggregate composition of the cement composition CaO rigs that causes loss of power and strength reduction due to rising real water cement ratio will affect large.

• Journal of The Korean Society of Agricultural Engineers
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• v.51 no.4
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• pp.43-47
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• 2009

Soil aggregation is an important part of influencing the soil behaviors in reducing rainfall-runoff and soil erosion, aeration, infiltration, and root penetration. Some inorganic materials such as clay minerals, Fe and Al oxides/hydroxides, and calcium carbonate can act as cementing agents within macroaggregates. The objective of this study was to determine the effects of different cementing agents (Fe, Mn, and Al) on soil aggregate formation in reclaimed tidelands. Water stable aggregate ratio and MWD (mean weight diameter) were higher in iron dioxides treatment than two other treatments. This result indicates significant correlation between soil aggregate formation and iron dioxides.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.61-62
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• 2015

This study has analyzed the engineering characteristics of resource-cycling mortar according to the variation of fine aggregate type using illite with high development potentials by setting the goal as developing eco-friendly construction materials. As a result, while flow has increased if recycled fine aggregate and waste refractory are used separately or mixing them adequately in case of flow and compressive strength, the flow had somewhat declined followed by illite replacement. However, the possibility of such usage is determined to be adequate if used by mixing illite, recycled fine aggregate and waste refractory properly due to the dry shrinkage effect.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2015.05a
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• pp.67-68
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• 2015

Recently, usage of ultra-high strengh concrete(UHSC) have been increased. Concrete has been recognized as a material which is resistant to high temperatures, but chemicophysical property of concrete is changed by the high temperature. So, mechanical properties of concrete may be reduced. Therefore, this study evaluated effect of the coarse Aggregate volume by high temperature mechanical properties of UHSC. Residual mechanical properties are evaluated under fine aggregate ratio 40,60% and 500℃ temperature on UHSC of W/B 15, 20%. As result, residual mechanical properties of UHSC are high by lower coarse aggregate volume.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.11a
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• pp.209-212
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• 2004

Recent economic development caused a vast use of mineral resources in Korea. Consequently, a supply of poor quality course aggregate (poor particle shape as well as poor gradation) in construction material become a social problem. In this study, an effect of aggregate particle shape on property of concrete was evaluated. The flat and elongation ratio of crushed aggregate was controled to 8, 15, 25, 35, and $47\%$ in order to evaluate fresh concrete behavior as well as physical properties in hardened concrete. Test result shows a poor aggregate particle shape cause a significant increase in entrapped air in fresh concrete, while no significant effect on hardened concrete property, such as strength as well as stiffness. This increase in entrapped air, however, believed to cause a significant decrease in concrete durability.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.525-528
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• 2006

Recently, Korea government prepared Act on facilitation of construction waste recycling in December 2003 for effective recycling of rapidly increasing construction wastes, and has enforced the Act on Jan. 2005. This Act limits the definition of recycled aggregates to the aggregates which obtained quality certificate and for this purpose, government has operated quality standard and certificate system of recycling aggregate. The objective of this experimental study is to evaluate the mechanical properties of recycled coarse aggregate concrete according to curing method by ready-mixed concrete. Compressive strength ratio of recycled aggregate concrete under air-dry curing/wet curing was $74{\sim}91%$. KCI code for conventional concrete overestimated elastic modulus for recycled coarse aggregate concrete.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2023.11a
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• pp.203-204
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• 2023

Recycled aggregate is an aggregate that satisfies the quality as an aggregate by crushing waste concrete and passing it through a separator. The government grants a floor area ratio of up to 15% and building height mitigation when more than 25% of the recycled building materials are used. In addition to environmental protection issues, it is necessary to actively utilize recycled aggregates that meet the standards to secure the business feasibility of buildings. This study attempted to derive the results according to the substitution rate by measuring the chloride ion diffusion characteristics based on the electrophoresis method.

• Architectural research
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• v.11 no.1
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• pp.25-33
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• 2009

This study presents the testing of 15 hwangtoh-based cementless concrete mixes to explore the significance and limitations of the development of eco-friendly concrete without carbon dioxide emissions while maintaining various beneficial effects. Hwangtoh, which is a kind of kaolin, was incorporated with inorganic materials, such as calcium hydroxide, to produce a cement-less binder. The main variables investigated were the water-to-binder ratio and fine aggregate-to-total aggregate ratio to ascertain the reliable mixing design of hwangtoh-based cementless concrete. The variation of slump with elapsed time was recorded in fresh concrete specimens. Mechanical properties of hardened concrete were also measured: including compressive strength gain, splitting tensile strength, moduli of rupture and elasticity, stress-strain relationship, and bond resistance. In addition, mechanical properties of hwangtoh-based cement-less concrete were compared with those of ordinary portland cement (OPC) concrete and predictions obtained from the design equations specified in ACI 318-05 and CEB-FIP for OPC concrete, wherever possible. Test results show that the mechanical properties of hwangtoh-based concrete were significantly influenced by the water-to-binder ratio and to less extend by fine aggregate-to-total aggregate ratio. The moduli of rupture and elasticity of hwangtoh-based concrete were generally lower than those of OPC concrete. In addition, the stress-strain and bond stress-slip relationships measured from hwangtoh-based concrete showed little agreement with the design model specified in CEB-FIP. However, the measured moduli of rupture and elasticity, and bond strength were higher than those given in ACI 318-05 and CEB-FIP. Overall, the test results suggest that the hwangtoh-based concrete shows highly effective performance and great potential as an environmental-friendly building material.

• Journal of the Korea Institute of Building Construction
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• v.16 no.6
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• pp.479-485
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• 2016

This paper presents an experimental study conducted to investigate the effect of recycled fine aggregate (RFA) on the mechanical properties and chloride diffusion behavior of mortar. The test results revealed that the addition of RFA plays an important role in the mechanical properties and pore structures of the investigated mortar specimens as well as chloride diffusion behavior. The mechanical properties such as compressive strength and flexural strength of recycled fine aggregate mortar (RFAM) were gradually decreased as RFA replacement ratio increase. The pore structure of RFAM was examined by permeability tests. The RFAM showed a increment in the permeability according to replacement ratio increase of RFA. But the chloride diffusion coefficient of RFAM was almost same up to 50% replacement ratio of RFA due to a chloride binding phenomenon of RFAM which may compensate the higher permeability of RFAM.