• Proceedings of the Korean Radioactive Waste Society Conference
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• 2004.06a
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• pp.43-51
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• 2004

In order to decommission the shielding concrete of KRR(Korea Research Reactor) -1＆2, it must be exactly determined activated level and range by neutron irradiation during operation. To determine the activated level and range, it must be sampled and analyzed the core sample. But, there are difficulties in sample preparation and determination of the measurement efficiency by self-absorption. In the study, the full energy efficiency of the HPGe detector was compared with the measured value using standard source and the calculated one using Monte Carlo simulation. Also. self-absorption effects due to the density and component change of the concrete were calculated using the Monte Carlo method. Its results will be used radioactivity analysis of the real concrete core sample in the future.

• 한국방재학회:학술대회논문집
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• 2011.02a
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• pp.160-160
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• 2011

현대의 건설기술은 자원절약과 환경보전이라는 시대적 흐름 속에, 자원순환과 지속 가능한 친환경 건설기술 개발은 차세대 연구분야로써, 연구가 시급한 분야가 되었다. 최근에는 골재 수급불균형 문제를 해결하고 동시에 자원순환을 위한 방안으로서 건설폐기물로부터 생산된 순환골재를 콘크리트용 천연골재의 대체재로 활용하기 위한 연구개발이 이루어지고 있다. 지속가능형 건설기술을 국내 독자 기술로 확립하고 건설현장에서 발생하는 폐기물의 순환시스템을 확고하게 구축하여 순환자원에 의한 국가경쟁력 강화를 기대할 수 있다. 본 연구의 목적은 순환골재 콘크리트의 역학적 특성을 개선하기 위해 순환골재 콘크리트 공시체를 제작하여 강도 및 강성을 검증하는 것이다. 실험방법으로 순환굵은골재의 치환 비율을 0%에서 100%까지 변화시킨 공시체를 제작하고 각 공시체의 정적 극한강도 거동을 비교 분석하였다. 하중은 공시체가 파괴가 발생 할 때까지 변위제어 방식으로 재하 하였으며 이 때 공시체의 파괴거동은 설치된 계측센서들을 이용하여 계측 및 분석하였다. 실험결과 공시체의 압축강도는 순환굵은골재 치환률이 25% 미만일 경우 일반 콘크리트 압축강도의 95% 이상의 구조성능을 갖지만, 순환굵은골재 치환률이 100%인 경우, 일반콘크리트 압축강도의 85% 수준의 구조성능을 나타냈다. 강성은 FRP 부재의 순환골재 치환률에 따라 최대 14%의 강성차이를 보였다. 이를 통해 순환골재 치환률이 높을수록 순환골재 표면의 폐모르타르와 이물질의 영향으로 재료간의 부착강도가 감소되어 강도와 강성이 저하되었음을 확인하였다.

• Journal of the Korean Ceramic Society
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• v.42 no.2 s.273
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• pp.99-103
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• 2005

Nowadays, large amount of waste pottery and porcelain annually are produced. It is needed that they are used as recycled materials in order to prevent environmental pollution and gain economic profits. Therefore, the purpose of this study is to present the method of utilizing the recycled aggregates that are obtained from waste pottery and porcelain as the concrete aggregate. The qualities of the recycled aggregate were compared with those of the crushed aggregate through measuring their physical properties. The test results showed that the replacement of crushed aggregate by recycled aggregate at the levels $10\%,\;20\%$, and $30\%$ had little effect on the compressive strength of the concretes, but higher levels of replacement reduced the compressive strength. Increment of the replacement of recycled aggregate caused increase in absorption ratio. As a conclusion, norman strength recycled aggregate concretes can be produced using less than $30\%$ of recycled aggregate.

• Journal of the Korea Institute of Building Construction
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• v.19 no.5
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• pp.383-389
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• 2019

The supply of natural aggregate for concrete has been difficult, and the amount of construction waste has been continuously increasing. Therefore, the necessity of using recycled aggregate made of construction waste as aggregate is rised. Therefore, many studies on the characteristics of concrete using recycled aggregate have been made and positive studies have been reported mainly in recent studies. A study on the chlorides binding effect of the mortar with recycled coarse aggregate has been reported. However, due to the user's perception of waste, most of the recycled aggregate currently produced is used only for low value-added products. In order to improve the recognition of recycled aggregate and the user's perception of recycled aggregate concrete, long-term monitoring of the structure with 100% recycled aggregate was conducted to confirm the applicability of the recycled aggregate concrete.

• Journal of the Korea institute for structural maintenance and inspection
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• v.11 no.2
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• pp.69-76
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• 2007

As amount of waste matter rapidly increases with fast growth of cities and industry, how to dispose them has arisen as an important problem. Current policy of the government on disposal of waste is repressing generation of waste itself and in case of already generated waste, resource cycle waste management system that recycles waste after proper environmental process is getting established. Therefore recycling of waste and industrial by-products is rising hugely. One of largely wasted matters is waste gypsum, which was categorized as designated waste but changed to general since 1994. Due to disposal cost and lack of impurities removal technology, recycling of it was quite low. However, as impurities removal technology using semi-dried desulfurization process is developed lately, study on recycling of waste gypsum is going on lively. This study examines possibility of utilizing waste gypsum as alternative for concrete cement and analyzed attributes of waste gypsum before and after ball mill process to find out proper alternation ratio, and conducted strength and property tests on concrete subject whose percentage of cement use is substituted with 0, 5.0, 7.5, 10.0 and 12.5% of waste gypsum.

• Journal of the Korea Concrete Institute
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• v.23 no.5
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• pp.647-656
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• 2011

In radioactive waste repositories constructed in underground, concrete member could be in contact with groundwater for a long time. However, this pure water creates concentration gradients which lead to the diffusion of Ca ions from the pore water and the degradation of underground concrete. Therefore, this study is aimed at investigating the alteration of pore structure and loss of compressive strength associated with dissolution. The results showed that as the leaching period became longer, the pore volume within 50 nm to 500 nm in diameter is greatly increased. Also, the volume of pores larger than 200 nm rapidly increased during initial leaching time and those below 200 nm gradually increased. Furthermore, the compressive strength gradually decreased with increase of degraded thickness. The residual strength of the degraded concrete with OPC was in the range of 33% to 58%.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2008.11a
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• pp.49-50
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• 2008

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2010.05a
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• pp.407-408
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• 2010

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2009.11a
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• pp.61-62
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• 2009

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2008.05a
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• pp.59-60
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• 2008